Extreme Heat, Housing, & Health with Dr. Gary Adamkiewicz

Why focus on homes and indoor environments for extreme heat and environmental risks? 

Extreme heat often brings to mind images of wildfires, scorched streets, and blazing sun. Yet Dr. Gary Adamkiewicz, director of the Harvard Urban Health Initiative and associate professor of environmental health and exposure disparities at the Harvard T.H. Chan School of Public Health, reminded participants that people experience heat most frequently inside their homes, since people spend about 90 percent of their time indoors. This means climate change influences not just the atmosphere but also the indoor environments people inhabit, where they face the significant and growing risks of thermal exposure.  

Climate and public health discussions tend to focus on visible phenomena: outdoor temperature maps, air quality indices, wildfire smoke. But residents’ bodies respond to what happens indoors: whether homes trap heat at night, whether ventilation works, whether mold and pests are controlled. That blind spot hits hardest for low-income households, renters, and communities already burdened by environmental injustice, where aging infrastructure, deferred maintenance, failing systems, inadequate inspection services, and high energy costs quietly expose residents to unhealthy conditions inside the place meant to protect them. Unfortunately, for many, the home operates as both a refuge and a risk. 

How can cooling interventions improve health for high-risk adults? 

Many people view air conditioning and other cooling methods as luxuries rather than health interventions. The “Beat the Heat” study in Boston, funded by the National Institutes of Health (NIH), investigates this issue by focusing on adults with chronic health conditions such as heart disease, lung disease, diabetes, and recent hospitalizations who live in high-need neighborhoods such as East Boston and Dorchester. For some individuals, a string of very hot days can shift their health status from stability to crisis. 

In the study, all participants received air conditioners, but researchers staggered the timing: some received them in summer 2025, while others received them in summer 2026. The team monitored thermal comfort in real time with sensors inside homes, used load monitors to track air conditioner use, and offered a $100 gift card subsidy to help offset the electricity costs that can make cooling feel like a luxury. An air conditioner a family can’t afford to run provides no benefit. This approach lets researchers assess how cooling benefits individuals under different conditions. 

So far, the evidence indicates that households with more reliable cooling report lower heat symptom scores. Another finding is that aggregate statistics often miss patterns of undercooling within a residence, which have been identified through speaking with residents in their living rooms. Some homes have undersized units; others have just one, often placed in the bedroom of the most vulnerable family members, such as children or elders, while other family members sleep in hotter rooms down the hall. City leaders and researchers rarely understand these details that many Bostonians face every day. 

Energy bills shape when and how long families run a unit; most understand the risks of heat but lack realistic, budget-friendly options. Viewed through this lens, access to cooling becomes an element of a broader question: what would a health system look like if it recognized the home as a site of care? Free or low-cost air conditioners, energy subsidies, environmental variables, and social support transform into a climate-health toolkit rather than disconnected emergency measures. The Beat the Heat study offers early but powerful guidance on how cities and health providers might design such systems at scale. 

What are cities and researchers doing to build heat resilience at the neighborhood level? 

While the Beat the Heat study focuses on individual households, the Cooling East Somerville initiative looks at the neighborhood level. Somerville, both physically and socially sensitive to heat, is Massachusetts’ most densely populated city. East Somerville, in particular, features low green space, high impervious surface coverage, and a significant proportion of immigrant and low-income residents. Here, the Cambridge Health Alliance, CultureHouse, and the city of Somerville’s Sustainability and Environment Division, with support from the Barr Foundation, are testing a suite of interventions, including individual-level measures such as air conditioner distribution and cooling kits for unhoused residents, built-environment changes with an ambitious depaving effort, and a community-level strategy aimed at creating pop-up cooling spaces. 

Depaving is both simple and radical. Rather than only adding trees or parks where convenient, the project team approached private property owners with $5,000 micro-grants and support to help them convert parts of their paved lots into greener, cooler spaces. Using GIS, the team prioritized parcels according to distance to bus stops and transit routes, the percentage of impervious surface, existing tree cover and shade, and environmental justice indicators. This spatial analysis ensured that they directed scarce resources to areas where they could most reduce heat exposure for sensitive residents. Paolo Padova, a fellow from the Harvard Urban Health Initiative, distilled lessons from East Somerville’s individual-level strategy into a case study about the team’s successes in engaging residents and partners, the difficulties they encountered, the workarounds they discovered, and the unresolved questions. This case study serves as a problem-solving document for other cities, helping them shorten their learning curve without pretending their contexts are identical. 

Can upgrading public housing actually improve health outcomes and save money? 

For two decades, Harvard researchers have partnered with the Boston Housing Authority (BHA), which is the city’s largest landlord, to study housing as a health intervention, with a focus on conditions in public housing that contribute to respiratory disease, particularly asthma, as families were experiencing high levels of asthma and other health problems. In collaboration with partners at Boston University and Tufts, researchers documented a familiar but critical list of indoor exposures, including allergens, secondhand smoke, combustion byproducts, pesticides, mold, and moisture. What followed was a sustained effort to change both policy and physical infrastructure, resulting in the BHA becoming the first large public housing authority in the country to adopt a smoke-free policy, which later contributed to the U.S. Department of Housing and Urban Development’s national smoke-free rule. Additionally, pest management shifted from periodic blanket spraying of synthetic pesticides to strategies that reduced both infestations and chemical exposure, and capital investments followed evidence on what makes housing healthier, not cheaper. 

The Old Colony development in South Boston became a central case through the Boston Residential Investigation on Green and Healthy Transitions (BRIGHT) study, a collaborative partnership between BHA, the Committee for Boston Public Housing and the Harvard T.H. Chan School of Public Health. In these buildings, older units were replaced with newer, green structures featuring electric stoves instead of gas, proper mechanical ventilation, smoke-free policies, and healthier building materials. Since the redevelopment took place in the same neighborhood, with many of the same families, the project functioned as a natural experiment in what happens when housing quality improves while context remains constant. The results were striking: 

• Indoor and fine particle concentrations fell by about 40 percent 
• NO₂ levels, closely linked to gas stove use and particularly dangerous for children with asthma, dropped by roughly 66 percent, indicating the shift from gas to electric cooking 
• Among children with asthma living in these homes, asthma symptoms, attacks, related emergency visits, hospital use, and missed school days fell by 3- to 5-fold.  

Adamkiewicz observed that if a pharmaceutical product achieved such an effect size, it would likely make front-page news. In this case, better housing provided the treatment. 

The new buildings are also cheaper: the first phase of about 130 units saved nearly $600,000 per year in utility costs. At a city-wide level, external data showed that over five years, adults living in BHA housing saw reduced asthma symptoms when compared with residents in market-rate and other subsidized housing. While this does not prove causality, the pattern supports the idea that intentional, health-driven enhancements in public housing can both save money and improve population-level health indicators. 

What are the practical lessons from working directly in people’s homes? 

Across the projects in Boston and Somerville, the common thread is that nothing replaces listening to people in their own homes. Researchers learned about undercooling, device-sizing problems, and household tradeoffs by standing in living rooms rather than solely evaluating data on spreadsheets. In Old Colony, researchers realized that, beyond the green buildings, residents could benefit from education on how to maintain healthy homes. This realization prompted the team to collaborate with the Massachusetts College of Art to develop ‘Welcome Home’ booklets to provide residents with information about their green homes. 

Energy subsidies and billing support emerged the same way, from feedback loops that let residents’ lived experience shape how programs were designed, adjusted, and scaled. People experience extreme heat at a human scale, and effective responses have to be built from that same scale: the data of daily life.   

How can academics and cities effectively partner on heat and housing? 

Neither the Beat the Heat nor the East Somerville case studies happened by accident; city-community-academic partnerships made them possible through time, trust, and institutional support. The Harvard Urban Health Initiative offers a model for structuring such work by linking mayors and city practitioners with researchers while ensuring evidence generated in one place does not remain siloed there. Building relationships with city staff, co-designing studies, and iterating on implementation is slow and labor-intensive. But Adamkiewicz underscored that if schools of public health want to genuinely serve communities, they need to rethink how they value this type of applied scholarship and action.  

The Harvard Urban Health Initiative uses embedded roles, such as fellows placed within city initiatives to help design, evaluate, and synthesize interventions, and course-based practica that embed students directly in city agencies or community organizations, which can potentially lead to extended collaborations funded through fellowships or grants. For Adamkiewicz, partnerships among city leaders, community stakeholders, and universities provide mutual benefits by connecting local expertise and student talent to real-world community needs, while preparing students for careers in public service. 

If you want to meet the challenge of extreme heat in a rapidly urbanizing world through joint efforts that value both the home and resident, please contact Dr. Adamkiewicz at gadamkie@hsph.harvard.edu.