Harvard researchers are launching three major studies funded by millions in grants to understand how air pollution harms our bodies and to create tools that help cities and countries reduce pollution-related disease. The projects, supported by Wellcome, a London-based charitable foundation, will investigate pollution's effects in the United States and India, offering new evidence to guide climate and health policies.

How Does Air Pollution Actually Damage Your Lungs and Heart?

Most of us think about air pollution as something we see—smog hanging over a city or smoke from wildfires. But the real danger is invisible. The tiniest particles, called PM2.5 (particulate matter 2.5 micrometers or smaller), slip deep into your lungs and can even enter your bloodstream. These particles come from vehicle exhaust, power plants, wildfires, and burning fuel for heating and cooking.

Mary Berlik Rice, an environmental respiratory health expert at Harvard T.H. Chan School of Public Health, is leading groundbreaking research to understand exactly how these pollutants trigger disease. With a $4 million grant, Rice's team will conduct two innovative studies. In the first, researchers will collect real pollution from urban hotspots, recreate it in the lab, and expose it to 3D models that mimic actual human airways. This allows them to watch, at the cellular level, how pollution causes or worsens specific diseases.

"We're grateful to Wellcome for supporting this innovative research that will help us understand the body's responses to specific pollutants at different levels of exposure," Rice said. "Starting at the cellular level—pinpointing how pollutants drive diseases like asthma, cancer, and heart attacks—we'll map out how communities across the U.S. are affected and develop evidence-based tools to inform climate mitigation strategies that can result in cleaner air and better health."

The diseases Rice's team is investigating include asthma, chronic obstructive pulmonary disease (COPD), cancer, immune system disruption, and cardiovascular disease. These aren't rare outcomes—approximately 16% of women newly diagnosed with lung cancer in the U.S. had never smoked, according to a 2020 study in JAMA Oncology. This means pollution in the air around us poses a risk that no lifestyle change can fully eliminate.

What Will These New Pollution Maps Show?

Rice's second project creates detailed maps estimating how much pollution people breathe across the entire United States. The team will calculate how different pollution exposure levels link to respiratory disease, cardiovascular problems, neuropsychiatric issues, and cancer risk. These findings will feed into a publicly available interactive tool designed for local and national policymakers to evaluate which climate mitigation measures actually work.

This is a major shift in how we approach environmental health. Instead of general warnings about "bad air days," policymakers will have precise data showing which pollution-reduction strategies save the most lives in their specific communities. "Ultimately, our goal is to provide clear mechanistic and population-level evidence that helps decisionmakers identify the best actions that can be taken today to improve air quality and health," Rice explained.

How Can Climate Policies Improve Health in India?

While Rice's team focuses on the United States, another Harvard research group is tackling a global challenge. India is the world's third-largest carbon dioxide emitter, and energy transition is reshaping public health there. Gaurab Basu, an environmental health expert at Harvard Chan School, received a $2.5 million grant to study how climate policies can improve health and economic outcomes in India.

Basu's team will work with India's government to develop the country's first national-level climate health model. This model will forecast how various climate policies will impact health, energy security, and economic growth through 2070. The researchers will also analyze real-world interventions, including electricity-reduction programs in the cities of Chennai and Delhi, and clean cooking techniques in coal mining communities in Jharkhand state.

"Energy transition is among the most critical issues facing public health in India and around the world," Basu said. "I'm thrilled to work with my research colleagues, and with community and policy stakeholders, to produce knowledge and resources that can inform policies that will improve and save lives."

Who Is Most Vulnerable to Heat and Pollution?

A third major study is examining a population often overlooked in health research: informal women workers in India. With a $3 million grant, researchers including Satchit Balsari and Caroline Buckee are leading Community HATS (Heat Adaptation and Treatment Strategies in South Asia), which is becoming the largest longitudinal evaluation of worker heat stress ever conducted.

The study enrolls women who work in marketplaces, workshops, farms, and streets for small daily wages. These women often live in poorly ventilated homes and face extreme heat exposure without workplace protections. Over 800 women are wearing devices that track their heart rate and sleep for one year, while researchers measure temperature and humidity in their homes and workplaces and collect data on wages, reproductive health, and mental health.

When the study concludes, it will have collected roughly 9.5 million distinct observations. The team plans to compile this into an open-access database and toolkit that communities worldwide can use to test heat adaptation interventions—like cooling roofs or new building materials—before deploying them at scale. The findings may also inform new financial tools, such as parametric heat insurance products that trigger hazard pay on extremely hot days.

Why Does Environmental Inequality Matter for Your Health?

One critical reality emerges from these studies: not everyone breathes the same air. Wealthy people don't live next to highways, but poorer neighborhoods—often on the east sides of cities where wind carries pollution—have always borne the worst air quality. This pattern traces back to redlining, a government-sanctioned housing policy from the 1930s that cemented racial and economic segregation.

The consequences are stark. A 2022 review in the Journal of Urban Health found that formerly redlined areas now experience higher rates of asthma, diabetes, high blood pressure, and poor mental health. In Detroit, residents of historically redlined neighborhoods have a life expectancy nearly 18 years shorter than those living in nearby "A-graded" districts.

What Are the Major Sources of Air Pollution Today?

• Transportation: Cars, trucks, and diesel engines emit nitrogen oxides and fine particles, making this the largest source of air pollution across the United States.
• Electricity generation: Fossil fuel power plants release sulfur dioxide, mercury, and other toxins from burning coal, oil, and natural gas.
• Wildfires: Increasingly, wildfires are driving sharp spikes in particle pollution and ozone across regions far from the flames, especially as climate change lengthens fire seasons.

Climate change amplifies each of these sources. Rising temperatures trap pollutants closer to the ground, while longer wildfire seasons and shifting weather patterns fill the air with more ozone, fine particles, and pollen. Dr. David Hill, Chair of the Board of Directors at the American Lung Association, noted that "each summer brings more patients gasping through the humidity" and that "allergy season is about a hundred days longer now in some parts of the country: the trees bloom earlier, the pollen stays in the air longer, and we feel it".

How to Protect Yourself From Pollution While Waiting for Policy Change

• Check air quality forecasts: Monitor daily air quality and pollen forecasts before planning outdoor activities, especially if you have asthma, COPD, or severe allergies.
• Adjust medications proactively: Work with your doctor to manage respiratory medications when air quality worsens, rather than waiting until symptoms worsen.
• Limit outdoor exposure on high-pollution days: On days with poor air quality, reduce time outdoors and keep windows closed to minimize inhaling fine particles.
• Advocate for local clean air policies: Support policies that reduce transportation emissions, encourage clean energy, and protect vulnerable neighborhoods from pollution sources.

The research being launched by Harvard scientists represents a turning point in environmental health. Rather than simply documenting pollution's harms, these studies are building the evidence and tools that policymakers need to act. By understanding exactly how pollution damages our bodies, mapping where exposure is highest, and testing which climate policies deliver the greatest health benefits, researchers are shifting the conversation from "pollution is bad" to "here's what works to fix it".

The stakes are high. These findings will inform policies affecting millions of people in the United States and India, two countries where air quality directly shapes respiratory health, cardiovascular disease risk, and life expectancy. For the first time, communities will have precise, evidence-based tools to guide their climate and health decisions.