As a researcher who was originally focused on infectious disease transmission models, Parham Azizi expected he would spend his career in a lab, but, as he told Inside Climate News in a recent interview, a wave of public health crises changed all of that: first the 2019 measles outbreak in Brooklyn, the COVID-19 pandemic, Hurricanes Ida and Ian, wildfires in Maui, and most recently the January 2025 wildfires in Los Angeles, CA.

All of a sudden, all of these crises happened, and they were all related to indoor air quality,” Azimi said. “It’s kind of defined my research.

When the fires broke out in Southern California earlier this year, researchers from Harvard Chan jumped into action and formed a consortium with other research institutions at UCLA, USC, UC Davis, and UT Austin, among others. The scale of this partnership is unprecedented, but it felt like a natural step to researchers at the Harvard T.H. Chan School of Public Health.

“In these national emergencies, I think all of us in this field feel compelled to do what we can to help,” said Joseph Allen of the rapid response of public health researchers to the fires. Dr. Allen is the director of the Harvard Healthy Buildings Program, and a Professor of Exposure Assessment Science in the Department of Environmental Health. He is also helping to lead the environmental exposures team on the LA Fire HEALTH Study.

In these national emergencies,” said Dr. Allen, “I think all of us in this field feel compelled to do what we can to help.

As part of the LA Fire HEALTH Study consortium, Dr. Allen and Dr. Azizi are working to understand what type of chemicals and toxins are present in homes and neighborhoods in the aftermath of these fires.

In addition to the reports sent back to homeowners taking part in the study, the preliminary findings have also been shared in the form of Data Briefs for the general public, distributed through the study’s website. These Data Briefs have shared indoor and outdoor air quality in the burn zones, VOC levels inside of homes, and most recently, the results of the tap water testing done by Dr. Azizi and his colleagues.

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Read more about the study in Inside Climate News here: After the LA Fires, Scientists Study the Toxic Hazards Left Behind.

Read more about the LA Fire HEALTH Study Consortium here: Long-term, multi-institutional study on health impacts of Los Angeles wildfires launched.

Visit the LA Fire HEALTH Study website.

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In April, the Trump administration announced cuts to the National Institute for Occupational Safety and Health (NIOSH). The planned cuts, which are scheduled to take effect June 1, will reduce the NIOSH workforce from approximately 1,400 full- and part-time employees to fewer than 150. While some workers in the coal miners’ health programs were granted reprieve last week, nearly all other NIOSH programs and divisions will still be eliminated.

The Harvard Chan Occupational Health and Safety Education and Research Center (ERC) is one of 18 regional centers across the United States funded by NIOSH. Founded in 1977, the ERC is dedicated to supporting the health and safety of workers through research and training. In addition to supporting research in the field of Occupational Health and Safety through its pilot project program, the ERC also supports trainees who are studying occupational health at Harvard Chan, creating a vital pipeline of new specialists into the fields on occupational medicine, industrial hygiene, occupational epidemiology, and more.

David Christiani is the Elkan Blout Professor of Environmental Genetics in the Department of Environmental Health at the Harvard T.H. Chan School of Public Health, and is a Professor of Medicine at Harvard Medical School. He is also the Director of the Harvard Chan ERC.

In a recent interview, Dr. Christiani explained the history of the ERC, the history of NIOSH and OSHA (Occupational Safety and Health Administration), and the critical importance of the field of occupational health for the safety of all American workers.

Can you tell us a bit about the history of NIOSH and OSHA?

DC: I think there’s a lot of confusion even among professionals about NIOSH versus OSHA: OSHA and NIOSH are essentially twins. They were born at the same time, created by the Occupational Safety and Health Act of 1970, which was established by a Congressional act signed by President Nixon at the time. The law created both agencies, NIOSH (in CDC) on the research and training side and OSHA (in Department of Labor) on the enforcement side.

NIOSH was modeled on the National Institutes of Health (NIH). They have no enforcement power; they are there to do research and educate the public. NIOSH was set up to do research on occupational safety and health problems and to educate professional disciplines in the relevant fields in things like industrial hygiene and safety, occupational medicine, nursing, occupational psychology, occupational epidemiology, and occupational toxicology. And then, with input from the researchers at NIOSH and other agencies (NIEHS from NIH, and NSF for example), OSHA sets the safety standards and regulates and enforces them.

NIOSH differs from the NIH in that it has a very broad mandate with a small budget, $323 million to keep 160 million workers safe. So that’s about $2 per worker per year.  Any other NIH agency with anything close to those responsibilities would have had more than a billion dollars annually.

But NIOSH has always done well. Even in a crisis. They froze the ERC and extramural research budget during Covid because it was a crisis. They didn’t take the money away, but they had to shift their internal priorities dramatically. This put a stop to a lot of the research they’re doing in certain areas and pivoted towards Covid prevention. They were able to do it pretty fast, especially in the areas of respiratory protection and workplace air quality, etc.  because they run as part of the US Public health Service, and that runs really well — despite stereotypes of government inefficiency  — they can run almost like a military speed to move and deploy people.

What was the state of worker health and safety in the US before the OSHA Act? I don’t think many people realize that it wasn’t until the 1970s that worker safety was really researched and regulated in the United States?

DC: I have to say, before 1970, it was like the Dark Ages. Still, there was some epidemiology going on. There was some corporate medicine and industrial hygiene. There was a dedicated division of industrial hygiene in the US Public Health Service that was folded into the new NIOSH.  But, it was in many ways the peak of the US economic and manufacturing power around that time, and it was felt to be pretty shameful that we didn’t have more investment in health and safety. And then there were two big things that led to the creation of these two agencies in 1970.

One was labor mobilization: There was a big strike in 1969 by the oil, chemical, and atomic workers, where the principal demand was not better wages, it was worker safety. There were too many fatalities and too many injuries, especially among oil refinery workers in places like Texas, Louisiana, New Jersey, you know, really across the country. And the strikes got a lot of publicity.

I read recently that the Harvard Chan ERC as the distinction of holding an early NIOSH grant, is that right?

DC: Yes, in the very 1st year of NIOSH, we’re one of several ERCs that started in 1977.

Similar to the NIH, NIOSH has an intramural program and extramural program, and the intramural program is about 1,300 people. So those are the people doing primary research at NIOSH. They do things like respirator research. For example, during Covid, that was who was telling us which N-95 masks to wear because they were NIOSH certified. If they weren’t NIOSH certified, they’re not guaranteed to work.  

And then NIOSH has an extramural program. That’s where the ERC comes in. The extramural program sponsors grants to universities and other institutions for research projects and for education and training.

These centers are able to specialize for the needs of their regions. For example, in Boston, our biggest industries, by far, are healthcare, construction, and education, and followed by things like financial services. And so in this region, our research and training focuses a lot on issues affecting workers in those particular industries: people working in labs and offices.

Our ERC has also been involved with educating fishermen here in New England, because it’s also a very high, hazardous industry. Forestry and fishing have the highest mortality, even more than mining right now in this country. And we support this industry through outreach to fishermen associations and societies in New Bedford, MA and Gloucester, MA and throughout Maine. The outreach is really about sharing best practices for healthy design: life saving materials, anti-entanglement devices, better engine designs, and other improvements. And generally fishing boats are small businesses: captains run their own boats that have been in the family for years. They need resources so they can modernize their boats and do it in a safe way.

But in other parts of the country, Centers focus on different issues. So, for example, in Colorado they’re dealing with nuclear energy workers and nuclear weapons, production workers, and radiation. In other regions the focus may be more on mining, manufacturing, or agriculture, etc. That means, all together, through this system we have a very diverse and robust network of training, education, and research training many different industries.

I think many people don’t think about NIOSH or OSHA affecting them if they are not working in a mine or in a factory? What are some of the ways that NIOSH is supporting other industries?

DC: Of course, manufacturing is only about 8% of the total workforce. Most of the workforce is actually in things like healthcare, professional business services, universities/schools and retail. And for those industries, for sedentary work, the problems we see are mostly things like musculoskeletal disease: joint problems, back problems, neck problems, shiftwork problems, reproductive, respiratory disorders, and so on. And, to respond to that NIOSH has shifted its inside and extramural focus towards the safety and so-called ergonomic factors that relate to those industries.

But also, especially in Boston, another big chunk of the workforce that parallels manufacturing, is construction, as you know, cities like Boston have lots of construction. Construction makes up about 5% of the national workforce, but it’s a disproportionate number of injuries and deaths compared to other industries. So, construction has always been a big focus as well for research and prevention of injuries.  

Finally, hospitals, and universities make up a large part of the workforce in this region — allergic conditions, blood-borne disease prevention, animal bites and other infectious concerns, asthma, skin conditions, and musculoskeletal and reproductive hazards are all active areas of research in NIOSH-related centers such as ours.

How did you personally get started in the field of Occupational Medicine?

DC: I was trained on one of our ERC’s first training grants back in 1979-81. After I finished my internal medicine training here in Boston, I was interested in lung disease and in lung toxicology, then I saw an ad at school for a fellowship that would lead to an MPH and certification in preventive occupational medicine, and that it was supported by this thing called the ERC and NIOSH. At the time, I didn’t know what either one of them was. I came and interviewed, and was really excited about what they were doing.  If it wasn’t for the ERC and the training grants, I wouldn’t have gotten into occupational medicine.

Once you started working in this field. What got you excited about the work?

DC: One of the big things I was studying was organic/vegetable dust, cotton textile dust in particular, and exposure in the lungs. The lung disease in those industries and agricultural environmental was different from what we were seeing in coal or asbestos. I had an R1 with NIOSH for more than 35 years to do this cohort study of textile workers in China that just completed a few years ago.

And fortunately, we also managed to finish a 40-year follow-up study of textile dust exposure, and it was important because it’s the same kind of exposures we have in grain workers in the US, and even workers in places like waste treatment centers. And because there’s bacteria that gets released, this work even has applications in schools and daycare centers. So, what started as research on textile workers became a kind of endotoxin-related research.

I also did work on welders jointly with NIOSH and NIEHS on the effects of welding fume particulates on inflammation of heart vessels and lungs. And all this work continued for decades actually right up until a few years ago, and NIOSH supported part of this work.

What do you think the risk is to public health with all these cuts to NIOSH?

DC: I think it would be pretty devastating, because what’s going to stop is not just the flow of research information — which in this country has always been important —  but also the practice of occupational health. Whether it’s regulatory reform or advice to companies on how to do things safely, this advice depends on having up-to-date knowledge. When you stop doing research and education in any field is you’re going to retard the development of up-to-date methodologies to keep people safe. I think it’s inevitable that you’re going to see increase in injury and illness in various sectors of the workforce.

The other danger is the knowledge generation will disappear.

What’s at risk is not just the NIOSH employees themselves, but also the extramural program which is training physicians and hygienists, epidemiologists, safety specialists, and occupational psychologists across the country. Once the training pipeline stops and people start retiring, you will not have the expertise for the companies to employ people to help them keep the workforce safe. So, I expect, [employers] insurance costs will go up, absenteeism will go up, quality of work life will go down.

We can lose, you know, a whole generation of professionals, and you have to start over again, and we’ll take a long time to rebuild this, to get back to where we are now.

Since ultimately these cuts are about improving the bottom line, what would these losses mean for employers and the economy?

DC: Absenteeism, loss of worker productivity, and compensation claims increasing. So, insurance costs going up. I think that’s just inevitable, because we’ve seen this in the past with state to state variation. When you have state OSHA programs that vary, you have different rates of injury and illness in those different communities. And NIOSH is the one providing the information either directly or through ERCs like ours.

So, for example, if we have another pandemic and then we’re not going to have the respiratory research lab working to get us the best information we can. NIOSH designed the method [during COVID] of how to reuse masks and sterilize the masks when we had a PPE shortage. And they did it within weeks. Who will do it now? I just don’t know who would step up and do it.

Why is the field of occupational health so important?

DC: Let’s compare to maternal-child health. We all think maternal child health is very important, right? You want to have healthy kids and then healthy kids grow up to be the workforce of the future. So, one could argue, you want to have a healthy workforce. You certainly want to have healthy kids, but you also want to have healthy working age people, if you’re going to be productive.

Occupational health, in a way, bolsters the general health of the population. So, the improvement is not just for their productive lives, but even in their post-retirement lives.

Do you think there’s an impact on the occupational health field with the demographic cliff of boomers retiring and the workforce shrinking, already? Does this compound that issue?

DC: Oh, it definitely compounds the issue. We know across the board that professionals in the boomer age as they leave that the need is bigger than what we’ve been able to feed the pipeline.  But, it’ll certainly even worse if that pipeline goes to 0.

That’s true across the board for scientific research, by the way. Even before this funding crisis we’re in, we did not have enough people trained to do the kind of things we want to do in research in general, in biomedical science. My colleagues here in HSPH doing work on conditions like tuberculosis, environmental pollution, forever chemicals in our products and the risks of reproductive, cancer, and immunologic disorders, global environmental health, nutrition and sustainability, etc. are all threatened, and I feel solidarity with them.

What do you think is the biggest threat to the ERC and this field in general?

DC: The strength of the ERC is our trainees: our master’s students, our MDs, our PhDs, our post-doctorate trainees.  They’re our hope. They are our future. So, I think, rather than any particular research topic, they are the future. And it is all being threatened right now.

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A new paper in the journal Science highlights the importance of integrating exposomics into mainstream biomedical research.  

Peng Gao, Assistant Professor of Environmental Health and Exposomics at the Harvard T.H. Chan School of Public Health, contributed to the paper as a member of the December 2023 Banbury Conference consortium on Integrating Exposomics into the Biomedical Enterprise. 

“Only a fraction of chronic diseases can be primarily attributed to genetic factors alone, highlighting the critical need to understand environmental influences through the exposomics approach,” says Dr. Gao. “In this paper, we elaborate that humans are exposed to multiple dynamic factors throughout their lives, yet research methods and regulatory agencies haven’t kept pace with this complexity, continuing to rely on a ‘one exposure at a time’ mindset.” 

Exposomics is an emerging field that aims to understand the comprehensive record of an individual’s environmental exposures throughout their lifetime. 

These findings could lead to improved methods for identifying environmental drivers of diseases, new approaches for monitoring individual exposures over lifetimes, evidence-based recommendations for reducing harmful exposures in vulnerable populations, and data-driven policies for environmental health.

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Breathing Easier Studio event highlights the ongoing fight for cleaner air, and the groundbreaking public health research from Harvard that has led the way 

Fifty years ago, researchers at Harvard set out to measure the health effects of air pollution in six cities across the U.S. — Harriman, Tennessee; Portage, Wisconsin; St. Louis, Missouri; Steubenville, Ohio; Topeka, Kansas; and Watertown, Massachusetts. The results of the Six Cities Study were dramatic, with the most polluted towns showing significant differences in mortality and life expectancy.  

The differences we found in life expectancy—two to three years shorter—were remarkable,” explained Doug Dockery, John L. Loeb and Frances Lehman Loeb Professor of Environmental Epidemiology, Emeritus, and lead author of the study’s landmark paper published in 1993. “Those are big numbers in terms of population life expectancy.

These findings had huge implications for public health and policy, including putting the concept of fine particulate pollution (PM2.5) on the radar of U.S. regulators. But it hasn’t been a simple or straightforward path to stronger clean air regulations.  

In, Particles of Truth, a new book by Doug Dockery and C. Arden Pope — a Professor of Economics at Brigham Young University, who joined the study team when he was a young visiting scholar at Harvard — the pair look at the history of the fight for cleaner air, including the pitfalls and speedbumps along the way. 

Both authors participated in a Harvard Chan Studio panel earlier this month to discuss the book, as well as the importance of research on air pollution and health impacts.

Breathing easier: The pursuit of clean air, brought together experts in clinical care and environmental health to discuss the threat of air pollution and explore solutions. Participants on the panel included Amruta Nori-Sarma, Assistant Professor of Environmental Health and Population Science; and Mary Rice, Mark and Catherine Winkler Associate Professor of Environmental Respiratory Health, and director of the Center for Climate Health and the Global Environment (C-CHANGE). The conversation was moderated by Kari Nadeau, John Rock Professor of Climate and Population Studies and chair of the Department of Environmental Health. 

Watch the panel here:

Following the Studio panel, the school hosted a book signing for Doug Dockery, where many students waited in line to have their copies of “Particles of Truth” signed, and snag a photo with the emeritus professor. 

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Researchers explain why their research to uncover environmental threats matters while offering practical information on how we can safeguard our health.

In a new collaborative video series launching today in celebration of Earth Day, environmental health scientists from leading universities across the country speak about the work they do to expose the invisible threats in our environment—from the air we breathe to the products we use—and offer practical tips on how we can protect ourselves.

The series kicks off with a short introductory video featuring Dr. Kari Nadeau, chair of the Department of Environmental Health at Harvard T.H. Chan School of Public Health, along with environmental health chairs from to Boston University, Columbia, Johns Hopkins, the University of Michigan, University of North Carolina, and the University of Washington, who explain—in plain language—why environmental health science is vital for all our lives.

Beginning today and over the coming weeks, additional videos will provide practical insights relevant to everyone’s health. They will also showcase scientists and students in action, collaborating with communities to turn research into real-world solutions.

“Many of the things that we take for granted as we wake up each day — clean, running water, clear air, safe food and drinks, and even safe schools and working environments — are thanks to the tireless work of environmental health researchers over the last century,” shared Dr. Kari Nadeau, chair of the Department of Environmental Health at Harvard T.H. Chan School of Public Health. “We want to highlight these findings and the ongoing research and education to understand new threats to our health from the environment as well as solutions.

Watch all of Harvard’s #EHworks videos on the Department’s Youtube Channel here.

In the initial round of videos, researchers and students describe connections between the environment and our health. Scientists discuss the role of green spaces to address the heat island effect in cities, and the importance of preventing toxic exposures during pregnancy to protect children’s health. They also talk about the impact of climate exposures on allergies and kidney disease and how reducing pollution is key to cancer prevention.

Dr. Mary Rice, Mark and Catherine Winkler Associate Professor of Environmental Respiratory Health, and the Director of the Harvard Chan Center for Climate, Health, and the Global Environment, is featured in one of the videos discussing her work on COPD and air pollution.

“Our research is looking for solutions to big problems that impact everyone’s health, like climate threats, wildfires, and air pollution,” shares Dr. Rice. “This research is vital to creating healthy and safe environments where everyone can live, work, and play.”

“People deserve to know how their surroundings affect their health and what they can do about it,” says Jonathan Levy, ScD, chair of Environmental Health at Boston University School of Public Health and one of the lead organizers of the campaign. “Environmental health research can give people the information they need to protect themselves and their families and to advocate for policies that keep people healthy.”

From wildfire smoke to “forever chemicals” in drinking water, environmental hazards are increasingly making headlines. Yet many Americans remain unaware of how scientists work in the laboratory, at the computer, in the field, and in collaboration with community partners to identify these health risks and develop ways to prevent illness and protect health.

The Environmental Health Works series aims to:

• Demystify science by showing the faces and stories behind the research.
• Connect the dots between environmental exposures like pollution or toxic chemicals and illnesses like asthma or cancer.
• Inspire action with practical steps to reduce risks at home and in communities.

You can watch all videos from participating universities here.

“Knowledge is power,” says Ana Navas-Acien, MD, PhD chair of Environmental Health Sciences at Columbia University’s Mailman School of Public Health. “When science shines a light on hidden risks—like toxic chemicals in water or air—families can make informed choices to stay healthy, and our leaders are equipped to seek solutions that protect us all.”

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On Tuesday, February 25th, the Department of Environmental Health hosted a film screening of the award-winning documentary, Until the End of the World, which examines the environmental and community impacts of fish farming. The screening was followed by a panel discussion and lively Q&A featuring filmmaker Francesco De Augustinis, as well as Alessandro Bocconcelli, Matthew Hayek, Doug Frantz, and Catherine Collins, and moderated by Eva Douzinas, President of the Rauch Foundation. 

Fish farming is the fastest growing sector of food production, often described as the sustainable answer for food security. Aquaculture attracts billions in public and private investment, which has led to the growth and expansion of fish farming projects in countries like Greece, Chile, and Argentina, with impacts to oceans felt in places as far away as Senegal and Antartica.

Petros Koutrakis, Professor of Environmental Health, introduced the film, drawing a parallel between the rise of industrial agriculture in the last century, and this century’s growth of aquaculture.

“We understand that it is a great challenge to feed over 8 billion people, but we cannot do it at the expense of the environment,” said Koutrakis. “Food production systems must cause minimum damage to the environment and human health.”

“There is often a disconnect between how people perceive aquaculture and the realities of its global impact, particularly regarding how much feed is required to produce salmon, sea bass, and other carnivorous fish, as well as the impact of these open-net fish farms on local ecosystems,” said Eva Douzinas, president of the Rauch Foundation which co-sponsored the event. “Discussions like this one at Harvard, which highlight the human impact via the documentary, and bring together experts on nutrition and the environment, are so important for driving progress and identifying areas in need of greater research and understanding.”

Today, fish farming — also referred to as aquaculture — is the fastest expanding food production sector globally. By 2021, the amount of farmed fish globally exceeded the amount of caught fish. Exact numbers when it comes to fish are practically impossible to secure, but it’s estimated that between 40-120 billion fish are farmed every year globally for an annual production of 122.6 million tons, according to the UN Food and Agriculture Organisation (FAO) in 2022. “If we go back 30 years ago, aquaculture did not have a production level so high,” explains Alessandro Lovatelli, FAO Aquaculture Officer, in the film, adding, “In the last three decades it has been going up steadily.”

Starting with sea bass and sea bream farms in Italy, Greece, and Spain, the documentary shows how fish farm pollution of natural paradises is transforming them into dead zones, not to mention the destruction of small local economies. We see the paradoxical competition of this industry versus the livelihoods of entire communities in vulnerable areas, to produce high-end products like salmon.

In many parts of the film, the word “colonialism” recurs, revealing an industry that is transforming portions of the sea into so-called ‘productive areas’, and relies on enormous quantities of pelagic fish such as sardines, anchovies and mackerel for processing into feed.

“Originally the fishmeal factories had the function of taking fishing waste, and processing it. But there is no more waste to be exploited because fish is scarce, and species that were not consumed before, are also consumed now,” explains Moussa Mbengue Adepa, a spokesperson for the traditional fishery association in Dakar, Senegal, West Africa. “So the fishmeal factories no longer transform byproducts, but are fed with small pelagic fish. But it takes 5kg of pelagic fish to produce 1kg of meal, you can see the ratio yourself.” So instead of feeding the local population, this fish is now used to create feed for fish farming that serves growing markets in Europe, Asia, and the United States.

To put this in context, Greenpeace Africa and Changing Markets Foundation estimate that 33 million people in West Africa could be fed each year with 0.5 million tons of fish that are exported and made into FMFO (fishmeal and fish oil). Serious questions are increasingly being asked about the ethical, as well as environmental and biodiversity, impacts of reducing small pelagic fish into fishmeal in countries like Senegal for transporting to farms feeding European and North American consumers demanding bass, bream or salmon.

This devastation of the local fish populations are having the dual effect of putting local fishermen out of work while also taking away a mainstay of the local population’s diets.

Alessandro Bocconcelli, Oceanographer emeritus of Woods Hole Oceanographic Institute, and co-founder of Centinela Patagonia in Chile, spoke on the panel after the film, and emphasized the need for much better regulation and oversight in the aquaculture industry. He likened fish farming in Chile to the “Wild West” with the industry charged with monitoring themselves and leading to growing environmental disasters.

Alessandro explained that because there are no villages near to where the fish farms are located off the Chilean coast, so the workers just live on barges next to the farms. “All the sewage from the barge goes inside this fish farm. Everything gets dumped at sea. So there is a huge problem with plastic pollution, and everything that dies in the farm also gets dumped at sea. So, it’s just a total disaster.”

Walter Willett, Professor of Epidemiology and Nutrition at Harvard Chan, addressed the audience after the film and discussed the challenges of trying to find a healthy and sustainable way to feed 8 billion people. Willett has previously discussed the direct health benefits of consuming farmed salmon, and has argued that these benefits outweigh the risks.

Willett explained, “This is a really serious, difficult challenge … because we’re obviously not feeding people well today. And at the same time we’re destroying our environment. And then we’re going to add a couple billion more people by 2050.”

Willett added, “From a health standpoint it does look like having about 2 servings of fish per week is best. And again, we’re back to this challenge that we’re already overfishing in many areas. And yet we’re still not having 2 servings a week produced and consumed at present.”

But there have been some proposed solutions.  Willett said, “It’s very clear that moving toward eating smaller fish, like sardines, and bivalves, such as mussels and clams could help meet this challenge”. He shared the recent work of colleague Chris Golden, who recently held a symposium on consumption of kelp and kelp farming, and integrating bivalves in kelp farming.

Another solution is to look for more plant-based sources of omega-3 fatty acids, but Willett highlighted that more research is needed in this area to determine if we can get the full health benefits of this essential long chain fatty acid by using plant-based sources such as canola or soybean oil.

“All of these things need to be done in a thoughtful, mindful, science-based way,” said Willett, in order to find the best way to provide people with more seafood in diets without leading to additional environmental and ecological destruction.

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We compiled a list of all of the questions we’ve received from people in the LA area in the wake of the Eaton and Palisades fires earlier this month, and spoke to environmental health researchers Kari Nadeau, Joe Allen, Mary Rice, Amruta Nori-Sarma, and Vanessa Kerry to get answers to these pressing questions.

• Questions about Air Quality
• Questions about Children and Schools
• Questions about Household Cleanup
• General Questions

Air Quality

Q: Why is wildfire smoke harmful to people? 

Wildfires produce a complex mixture of air pollutants, including fine particulate matter, referred to herein as PM_2.5; this denotes small solid particles and liquid droplets in the air that are smaller than 2.5 micrometers in diameter, which is roughly 20-30 times smaller than the diameter of a human hair. Since these particles are so small, they are easily inhaled deep into the respiratory system, which can cause a myriad of negative health effects. These can range from coughing and throat and nose irritation to exacerbated asthma symptoms, altered heart and lung function, heart attacks, and even premature mortality, particularly among those with underlying health conditions. One study estimated chronic health impacts from indoor exposures to various air pollutants and found PM_2.5 to account for the greatest burden, making them especially important to protect ourselves from.  

While there are ambient particles every day in the air we breathe, the high toxicity of wildfire smoke is due to a combination of the higher concentrations of particles in the air during and after wildfires, as well as differences in the chemical makeup of the particles that form during wildfires. Different material burnt leads to different types of particles, which can also cause different health harms.  

More research is still needed about what might be in the air after an urban wildfire, and how long it will stay in the air, but we know that for weeks, if not longer, exposure to particles in the air is a risk for everyone. 

Q: Who should wear a mask and when?  

Experts are advising everyone in proximity to the burn areas to wear a mask out of an abundance of caution. We recommend wearing a mask while outside, for at least a month after the fire. It is most important to mask if you see or smell smoke in the air, and the mask should be at least an N95 (or KN95). Surgical or cloth masks used during COVID will not protect from the fine particles contained in wildfire smoke.  

For those who are more at risk of adverse effects (include people with underlying respiratory and cardiovascular conditions, children, infants, pregnant people, and people over 65), we recommend masking for up to 100 miles away from the fire.  

One way to think about exposure is exposure over time within closer proximity to the burn area: so, the longer you will be outside, and the closer you are to the burn area, the more important it is to wear a mask. To limit exposure, it is best to limit time outdoors, especially doing strenuous physical activity.  

This recent article from the NY Times features recommendations from Dr. Kari Nadeau and Dr. Joe Allen, and has important tips for choosing a mask, indoor air purifiers, and even fitting masks for young children.  

Q: For how long after the fires are contained/put out, should we continue to mask outdoors when the AQI is yellow or above? 

Experts recommend masking for at least a month after the fires are contained or put out. 

Q: Which air purifiers are best for filtering out pollutants from wildfire smoke inside your home? 

You want to use an air purifier with a HEPA filter, which will be effective for cleaning particles in smoke from inside your home. Your air purifier doesn’t need to have a UV or ionization option. If you’re looking for specific brands, check out this NY Times Wirecutter Review for some recommendations. 

You can look for the ‘clean air delivery rate’, or CADR, that the manufacturer should report. This is an indicator of the effectiveness of the device, so you can make sure it’s sized correctly. Our rule-of-thumb is to look for a CADR of about 300 for a 500 square foot room. 

For those who are closest to the burn area with a home directly impacted by soot and ash, there are also air purifiers that have HEPA filters combined with an activated carbon or activated charcoal filters. These air purifiers can help capture the particles (the HEPA filter) and also gases (the activated carbon filter). 

Also, if you have central air conditioning or heating in your home, upgrade your HVAC filter to a Minimum Efficiency Reporting Value (MERV) 13-rated filter or higher. MERV ratings signify an air filter’s effectiveness at lowering airborne particles and pollutants, determined by the smallest particle it’s capable of trapping (in microns). It is also recommended to always change your filter immediately following a fire, as wildfire smoke can affect filter performance. 

To ensure the air inside your home is healthy, Healthy Buildings recommends following the “hierarchy” of good indoor air quality, which focuses first on source control, then ventilation, followed by air cleaning. Here we present strategies specific to wildfire smoke: 

• First, you want to limit the amount of polluted outdoor air that makes its way indoors. Start by closing all windows and doors, and ideally seal up any noticeable cracks or openings in exterior walls (i.e., reduced infiltration).  

• If possible, do not use swamp coolers or whole house fans that bring in outside air. In this case of wildfires, you actually want reduced ventilation. 

• Next, use an indoor air filter to clean the particles from your indoor air, this can be a portable HEPA air filter or a MERV13 or higher filter on your central air system (or a combination of both). 

Learn more here: https://healthybuildings.hsph.harvard.edu/protecting-your-health-from-wildfire-smoke-spotlight-on-filters/ 

Q: How far away from the fires do we need to be concerned about health impacts and air quality? 

– If I live in between two burn zones, does this mean I am safe or more at risk? 

– If I was out of town when the fires happened, is it safe to return home if it is only a mile from the burn site?  

– How far from the burn zone is considered a safe proximity? 

– How far might the polluted air travel?

Many of these questions are difficult to answer because there is still a lot of uncertainty. Even people 50-100 miles away from the affected area could experience adverse health effects from the fires. The Harvard T.H. Chan School of Public Health, along with UCLA Fielding School of Public Health and other local partners, has just announced a 10 year study to investigate the health effects of the fires. I encourage you to reach out to Dr. Joe Allen and his study team to request your property be tested and monitored by emailing forhealth@hsph.harvard.edu.

In general, we’d recommend using these 3 questions as a guide to determine the level of precaution you might want to take: 

• Did you see it? If you saw – or still see – visible dust or ash, you should take the extra precautions we provided in this document. 
• Can you smell it? If you are still smelling smoke and/or ash and/or ‘fire smell’, that is most likely the off-gassing of chemicals that have absorbed into materials in your home or school. If you can smell it, you should take extra precautions. 
• Can you sense it? If you are unsure, we recommend purchasing one of the portable air quality sensors listed in our guide. Look for one that measures airborne particles (PM2.5) and airborne gases (TVOCs). These are imperfect measures, but will give you a sense of how your space is being impacted or not. For more information on these sensors, and how to interpret the data, you can read this article. The article is written for businesses, but the information on sensors and what they measure are relevant for homes and offices, too: Harvard Business Review: It’s Time for Companies to Monitor Workplace Air Quality 

Regardless of your distance from the burn zone, watch out for symptoms of smoke exposure such as dizziness, coughing, chest pain. These symptoms can occur even 5 days after exposure to an AQI of 80+. If you experience these symptoms, please see a doctor immediately.

Q: How can we monitor dangerous airborne substances which aren’t included in the AQI shown by most weather websites? 

– Can you recommend an air quality tester? 

The Air Quality Index (AQI) as published by airnow.gov is an excellent way to see what is generally happening with air quality outside your home, but it might not be accurate down to your exact location, and it can’t capture the quality inside your home. The AQI measures ground-level ozone, particulate matter (fine PM_2.5 and coarse PM₁₀), carbon monoxide, sulfur dioxide, and nitrogen dioxide. 

To check the safety of the indoor air in your home, you will want to look for an air quality monitor that measures fine particles (PM2.5, in addition to volatile organic compounds (VOCs) and carbon dioxide (CO₂). Read a recent NY Times Wirecutter review of air monitors here. 

Q: Ash is everywhere, is this toxic? 

The ash could be potentially toxic. Complex chemical reactions from burning things like paint, furniture, building materials, cars, electronics, and more can potentially make ash toxic. A lot of items in homes are made of petroleum and different composites that can be extremely hazardous when they combust. People who are involved in recovering ash could face increased health risks from inhaling potential toxins. Scientists are still trying to understand the health impacts of those chemical changes on human health. 

Residents should not attempt to remove or clean hazardous fire debris themselves. Post-fire house debris is hazardous because it can contain toxic materials like asbestos, lead, mercury, chemicals from household products, and other heavy metals which are released into the ash and debris when structures burn. These materials pose a risk to health if inhaled or handled improperly. Planning is underway for Debris Removal Activities in coordination with the County Office of Emergency Management and our State and Federal Partners.  Residents should check recovery.lacounty.gov frequently for updates on the debris removal program. 

Once the local government has determined that it is safe to re-enter your property, or if your home was not located in a burn zone, you may still want to consider hiring a professional clean-up crew. There are fire remediation companies that can be hired to help assess your home for fire or smoke damage, support clean up and advise on safety. 

If you enter a property with visible ash to examine the damage or recovery items, it is important to mask, wear gloves, and be as cautious as possible. We recommend wearing a high-grade respirator (ie, mask), specifically a P100+multi-gas mask. These can be purchased online and at local hardware stores.  

Children and Schools

Q: How does wildfire smoke impact young children — particularly during pregnancy — and what can communities do to protect children both during and after a wildfire? 

Although wildfire smoke affects everyone – it is especially harmful to young children and pregnant persons. During pregnancy, exposure to wildfire smoke can trigger the body’s inflammatory response, which can lead to problems such as gestational hypertension, preeclampsia, low birth weight, and preterm birth. Preterm birth is associated with poor health outcomes later in life, including impaired cognition, reduced growth, and chronic health issues.  

Young children are also at risk of adverse health effects during and after wildfire episodes. Children have higher rates of respiration and more active systems than adults, making them more likely to inhale high levels of harmful particles during outdoor playtime. Young children have increased rates of emergency visits for asthma after exposure and higher rates of upper respiratory infections, pneumonia, and bronchitis. Wildfire smoke exposure is also related to poor learning outcomes. A nationwide study found that students with exposure to smoke a year leading up to a test, particularly on school days, had lower average scores, the more smoke they were exposed to.   

To protect children during and after a wildfire, children should wear N95 masks, or if they are too young to mask, they should have as little exposure to outdoor air as possible. Children should also be exposed to clean air spaces. Schools, daycares, business, and other places where children spend time should have clean air shelters with well-sealed windows, and central air systems should be fitted with filters that are rated MERV13 or higher. Filters in portable units must be changed after a wildfire since reactions with the smoke can cause them to be more ineffective.

Learn more about the impact of wildfire smoke on children in this new brief from the Center for the Developing Child at Harvard University:

• Growing Up in a Warming World: How Wildfire Smoke Affects Early Childhood Development

Q: How important do you think it is for schools to have a carbon filter (in addition to HEPA) in the air purifiers in each classroom? 

The most important thing is to ensure that there is good filtration in the classroom by upgrading and changing out filters in the air handlers (e.g., MERV13 filters) and using portable air cleaners with a HEPA filter. Each classroom does not necessarily need to have a portable air cleaner with a carbon filter in addition to HEPA.  

HEPA filters are excellent at capturing airborne particles, and carbon filters can be effective at capturing gases. However, there are limitations to carbon filters (e.g., most don’t have a lot of carbon and the filter can ‘saturate’ very quickly (meaning, they no longer capture gases); it’s hard to predict when they will saturate because it depends on many unknowable factors; they are expensive.)  

We would recommend the decision of whether to use carbon filters be based on how impacted the school was.  For example, if your school is close to the burn area and had visible soot/ash, it’s likely that porous materials absorbed smoke and can off-gas for many weeks. These schools need a deep-cleaning, and should consider discarding porous materials and, if not discarded, these materials should be given time to off-gas (this requires good ventilation). After cleaning, and as an added precaution, highly impacted schools could opt for these portable air cleaners with carbon – just look for one with HEPA filters and as much carbon as you can find. There are models that have 15-30 pounds of activated carbon. 

Q: Is it safe to send kids to school, particularly as clean-up and rebuilding begin? 

Schools that are impacted should be thoroughly cleaned before re-entry. Ideally air, water, dust, and soil testing should be completed, in particular for schools nearest to the burn area. In addition, we recommend enhanced filtration after the cleaning, and installing air quality monitors in classrooms to measure airborne dust (e.g., PM2.5) and airborne chemicals (e.g. TVOCs). 

Q: Do we need to get rid of school supplies that were exposed to ash and smoke?

This will depend greatly on where your home/school was located and how close it was to the burn zone and smoke/ash from the fires. If you want to act out of an abundance of caution, items that should be discarded include items made from porous materials, or items that easily absorb smoke. These include paper items such as schoolbooks, fabric-based materials such as backpacks and clothes, and plastic-based items.  

Here are some resources to look at when deciding what items to get rid of or how to proceed with cleaning:

• https://calrecycle.ca.gov/disaster/wildfires/homeowners/, 
• https://www.maca.gov.nt.ca/sites/maca/files/resources/returning_home_safely_after_a_wildfire_-_may_2023.pdf 

Household Cleanup

Q: What do you recommend to reduce toxins that are brought inside from pets? 

After going on walks outdoors, wipe your pets’ paws and coat with a damp cloth. Also consider bathing pets more frequently if they are going outside a lot. Also, continue to damp wipe areas of the home where outdoor dust can be brought in easily (e.g. entryways), and vacuum regularly. Use a vacuum with a HEPA filter that is air-sealed. Some vacuums will pick up soot and dirt and capture the big particles but then redistribute smaller particles back into the air. This article explains why you want a HEPA filter, and why finding a vacuum that is air-sealed is important: Are HEPA Vacuums Worth It? Think Twice Before Spending Big. | Reviews by Wirecutter 

LA County put together this helpful fact sheet about caring for pets after the fires: http://publichealth.lacounty.gov/vet/docs/WildfirePetSafetyFactSheet.pdf  

Q: What household items need to be replaced? 

This will depend greatly on where your home was located and how close it was to the burn zone and smoke/ash from the fires. Sifting through debris is not recommended as it can be very dangerous. LA County has a helpful resource about what their cleanup teams are removing from damaged properties here: https://recovery.lacounty.gov/returning-after-fire-faq/ 

If your home was not in a burn zone but you are worried that your home was exposed to smoke/debris from nearby burns, you should discard most food items, including jarred items that may have been exposed to heat or smoke. Cleaning products, paint, batteries, and electronics should be thrown out to mitigate risk as well.  

Please check the LA County Recovery website for details about property cleanups and timelines for your neighborhood: https://recovery.lacounty.gov/returning-after-fire-faq/ 

There are also fire remediation companies that can be hired to help assess your home and belongings for fire or smoke damage, support clean up, and advise on safety. 

Q: How do you clean surfaces in your house?

Residents should not attempt to remove or clean hazardous fire debris themselves. Post-fire house debris is hazardous because it can contain toxic materials like asbestos, lead, mercury, chemicals from household products, and other heavy metals which are released into the ash and debris when structures burn. These materials pose a risk to health if inhaled or handled improperly. Planning is underway for Debris Removal Activities in coordination with the County Office of Emergency Management and our State and Federal Partners.  Residents should check recovery.lacounty.gov frequently for updates on the debris removal program. 

If your home was not in a burn zone, but you are worried about smoke/ash inside your home, please keep the following tips in mind. Different types of surfaces need to be cleaned differently. When cleaning, always wear household dishwashing gloves, long sleeve shirts, and long pants, to avoid the ash irritating your skin. We recommend wearing a high-grade respirator (ie, mask), specifically a P100+multi-gas mask. These can be purchased online and at local hardware stores.  

Also wear safety goggles, not glasses, so that ash won’t get in your eyes. To clean up ash, try gentle sweeping and then wet mopping, trying not to stir the ash into the air.  HEPA filter vacuums can be used, but do not try to use a standard household vacuum. Ash can be discarded in the regular trash, but make sure to put it in a plastic trash bag first so the ash doesn’t blow away. For more recommendations, please visit the LA County Recovery guidelines for clean-up after a fire:  https://recovery.lacounty.gov/returning-after-a-fire-public-health/ 

General

Q: What other reliable sources of current health info can we turn to in the coming months? 

Aside from the resources that we have included in this newsletter, be sure to stay up to date on current health information by looking for articles with new research. There is a lot of new health information that is shared online as more research about the effects of the fires is conducted. Also, be sure to check local and state government websites, that have a lot of helpful information about how to best protect yourself.  

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Joe Allen, Associate Professor of Exposure Assessment Science in the Department of Environmental Health, has taught the Healthy Buildings course at the Harvard T.H. Chan school of Public Health since 2016. Over the years he has had many students at the Harvard School of Design take the class. But this spring will mark the first time that the class is officially cross-listed at both Schools and be co-taught with Dr. Allen and GSD’s Dr. Holly W. Samuelson. 

“There’s magic when public health students and design students are in the same room,” says Allen, “because it forces interactions between the fields that unfortunately haven’t always happened historically. Very few universities have both a design school and public health school, so we have an incredible opportunity to merge the disciplines right on our own campus.” 

In the class, public health and design students will explore building strategies that can improve indoor air quality, help prevent the spread of airborne infectious disease, reduce exposure to toxic materials, improve thermal resilience, and support overall well-being, while also examining the role buildings play in our energy system, the cascading health impacts of associated air pollution and climate change, and building design and technologies that can support climate mitigation, climate adaptation, and climate resilience. 

This course is jointly offered by Harvard Chan as EH 252 and the GSD as SCI 6361. It will meet for the first half of the semester (January 30–March 6, 2025) at Harvard Chan and the second half (March 13-April 24, 2025) at the GSD. 

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A new study published today in Lancet Planetary Health found that long-term exposure to air pollution increased deaths by 1.5 million deaths per year in India, when compared to conditions if India met the World Health Organization’s recommendations for safe exposure. 

Air pollution consisting of particles smaller than 2.5 micrometers in diameter, PM2.5, can enter the lungs and bloodstream and is a major health risk in India. Researchers have now examined the link between these particles and mortality over a ten-year period (2009-2019). Unlike previous studies, this study was across all of India and used a new model of PM2.5 for every 1x1km of the country.  

“We found that every 10 microgram per cubic meter increase in PM2.5 concentration led to an 8.6 percent increase in mortality,” said co-author Joel Schwartz, PhD, faculty member in the Department of Environmental Health at Harvard T.H. Chan School of Public Health. “The increase was even larger for 10 microgram per cubic meter increases in PM2.5 from levels below the Indian guidelines of 40 micrograms per cubic meter.”

“The results show that current guidelines in India are not sufficient to protect health. Stricter regulations and measures to reduce emissions are of utmost importance,” said co-author Petter Ljungman of the Karolinska Institute in Sweden. 

“Delhi may get the headlines, but this is a problem all over India, and nationwide efforts are needed. Coal burning electric plants need scrubbers, crop burning needs to be limited, and most importantly, the government needs to recognize this as a major issue,” said Dr. Schwartz. 

The study also highlights that the entire population of India lives in areas where PM2.5 levels exceed WHO guidelines. Hence 1.4 billion people are exposed year after year to air pollution that can negatively affect health. In some regions, levels of up to 119 micrograms per cubic meter were measured, significantly higher than what both the WHO and India consider safe. 

The study is a collaboration between researchers from universities in India, Sweden, USA, Israel and Italy. 

Publication: ‘Estimating the effect of annual PM2-5 exposure on mortality in India: a difference-in-differences approach’, Suganthi Jaganathan, Massimo Stafoggia, Ajit Rajiva, Siddhartha Mandal, Shweta Dixit, Jeroen de Bont, Gregory A Wellenius, Kevin J Lane, Amruta Nori-Sarma, Itai Kloog, Dorairaj Prabhakaran, Poornima Prabhakaran, Joel Schwartz, Petter Ljungman, The Lancet Planetary Health,  Published December 2024. DOI: 10.1016/S2542-5196(24)00248-1

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Dr. Megan Solan, a fellow in Jin-Ah Park’s Lab, presented the poster entitled “Perfluorohexanoic acid (PFHxA) Induces Cytochrome P450 1A1 and 1B1 Expression and Enzymatic Activity in Primary Human Bronchial Epithelial Cells (HBEC) Cultured in Air-Liquid Interface (ALI)” at the SETAC North America 45^th annual meeting on October 20-24, 2024.

“The research I presented at the SETAC annual meeting focused on Perfluorohexanoic acid (PFHxA). PFHxA is a type of PFAS, a group of chemicals often called ‘forever chemicals’ because they don’t break down easily,” Dr. Solan explained. “PFHxA has recently been found in household dust, which inspired us to study the effects of exposure on airway epithelial cells that protect us from airborne contaminants. Our research showed that PFHxA exposure increases mRNA expression of Cytochrome P450 (CYP450) enzymes, which are crucial for metabolizing toxicants and drugs into a form which can be excreted by the body. This is significant because PFAS are known for their persistence in the body, raising questions on why PFHxA would affect CYP450 enzymes without being metabolized.”

Dr. Solan notes that PFAS are a hot topic at SETAC conferences, with attendees including consultants and EPA scientists who influence risk assessments and legislation.

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