Climate + Chemicals + Human Health

^{Article originally published November 2023 with updates in July 2026.}

We have been curious about (and concerned by) the intersection of chemicals, indoor air quality (IAQ), and rising temperatures caused by climate change. We spend 90% of our time indoors, and the materials that make up our indoor environment and the chemicals used to make them have a major impact on our health. But those materials don’t exist in a vacuum. Changes to our outdoor environments impact the way materials (and the chemicals within) perform indoors. Warmer temperatures heat the materials in our living environments (and the chemicals within them) - and then what?!
 

According to researchers at UC Berkeley, “There is little published literature that specifically considers the effects of climate change on indoor air quality that would influence public health.” 

We do know that designing buildings with biogenic and geogenic materials—those derived from plant, animal, and mineral sources with fewer synthetic additives—offers a pathway to reduce chemical burden while also building climate resilience. 

Recently, more information is revealing the impacts of hotter climates on our indoor environments  Here we share our initial findings as we try to answer the question:  

Studies are beginning to show a clear link between rising global temperatures and deteriorating indoor air quality. According to a report in the International Journal of Environmental Research and Public Health, “The increase in temperature may lead to higher indoor concentrations of airborne pollutants causing higher risks of allergy, cancer, and endocrine disruption.” These are risks associated with a host of toxic chemicals commonly found in building materials and furnishings. While there are many surfaces in the interior that contain VOCs, we look at one product as an example - specifically, laminate flooring.

The graph below shows an increase in VOCs off gassing from laminate flooring, specifically the resins within its composition. VOCS are evaluated through two metrics; TVOC refers to Total Volatile Organic Compounds and 5VOC refers to the five specific VOCs: benzene, toluene, ethylbenzene, xylene, and styrene. As the temperature rises from 25 celsius to 45 celsius, TVOC levels increase more than 3 times.

Beyond Laminate, common surfaces and furnishings show between modest changes, to dramatic spikes in VOCs and aldehydes released into the air. The table below illustrates how much emissions can increase from typical building materials under elevated* conditions.

^{*UL Research Institutes’ Chemical Insights Research Institute (CIRI) tested common building materials at an elevated temperature of 95°F (35°C), compared against an average room temperature of 73.4°F (23°C).}

Studies addressing the impacts of specific materials can help us to identify and replace harmful materials with no or low VOC alternatives. In practice, this often means shifting toward bio- and geogenic materials with simpler chemistries and lower VOC profiles. These materials are generally more resilient and can better tolerate a warming, more humid climate without dramatically increasing indoor pollutant loads. We are also interested in models which can quantify the increased chemical exposure impacts across a whole room or building, displaying the significance of material health at a larger scale. Scientists are working on holistic models to predict indoor air quality based on future climate predictions. The Indoor Air Quality Climate Change Model looks at 5 submodels as inputs which influence the overall indoor air quality:

1. Building Physics: Based on a hygrothermal¹ simulation model, including temperature, humidity, building envelope, and ventilation
2. Emissions: From materials (floor coverings, wall surfaces/coverings, plaster, furniture) and from human behavior (cooking, candles, cleaning, electronics)
3. Chemical-Physical Processes: VOC degradation into aerosols and particulate matter
4. Mold Growth: Based on mathematical models of mold potential
5. Human Exposure: Inhalation of particles, gasses, deposition in lungs, microorganism exposure, thermal comfort

VOCs are just one of the ways our indoor environments are compromised. We advocate for scientists to include other kinds of chemical degradation in building products, human exposure methods and pathways into future models. 
 

Graph of IAQCC submodels on Emissions and Chemical-physical processes²

While models like the IAQCC are hugely beneficial as we adapt the way we build for the climate of the future, the impacts of climate change are being felt right now. Importantly, they aren’t being felt equally. Globally, urban areas face higher temperatures and residents of those areas with less green space will continue to suffer disproportionately as temperatures rise. In the US, neighborhoods across the country that were redlined in the early 20th century are typically the hottest in their respective regions. According to the New York Times, “neighborhoods that are poorer and have more residents of color can be 5 to 20 degrees Fahrenheit hotter in summer than wealthier, whiter parts of the same city.”

This image below by the New York Times shows Richmond, Virginia. Past redlined³ areas are significantly warmer than other parts of the city.

Reducing the impacts of climate change will take a global effort and cooperation. As we consider the role that architects and designers play, one thing is certain: we must radically change the way we make and use building materials. Fortunately, the path for that change is clear. We know that there is a link between toxic chemicals and their human health impacts. We know many materials that contain these toxic chemicals and we have identified healthier material alternatives. Prioritizing biogenic and geogenic materials—such as mass timber, natural fiber insulation, clay‑ and lime‑based finishes, and other mineral‑rich assemblies—can lower chemical exposures while also supporting carbon storage, repairability, and passive performance. Rising temperatures accelerate the need to stop using toxic materials. The consequences of staying with the status quo is becoming even more of a risk to human health. For the sake of our planet and its population, we must make the shift to healthy materials as a strategy for health and climate resilience.

We see a clear relationship between Chemicals x Climate Change x Human Health. This intertwined relationship and identifying necessary strategies for change are key goals of Healthy Materials Lab.

As we continue to explore this research with experts in the US and Europe we will report back on what we find!
 

Since we first published our observations in 2023, new research has strengthened the connection between climate change, indoor air quality, and human health. A 2022 review by Mansouri et al. in the International Journal of Environmental Research and Public Health synthesized evidence that rising temperatures can increase indoor concentrations of airborne pollutants, elevating risks of allergy, cancer, and endocrine disruption, and a 2024 American Thoracic Society report has further integrated these indoor exposures into mainstream air pollution and health guidance. The newly added table “Increase in TVOC and TALD (In Elevated Conditions)”, based on laboratory testing, shows how elevated temperature and humidity can dramatically increase VOC and aldehyde emissions from common interior materials, with some products exhibiting several‑hundred‑percent jumps in chemical release. Building on this, a 2025 year‑long field study of occupied homes documented that VOC off‑gassing from indoor surfaces peaks in warmer months, confirming that emissions track seasonal temperature and humidity rather than remaining constant across the year. Taken together, the laboratory and field evidence underscores that hotter, more humid indoor conditions, driven by climate change and uneven access to efficient cooling and ventilation, can sharply increase chemical loads in the very spaces where people seek refuge from extreme weather.

During the heatwaves in June and July 2026, indoor temperatures in the USA came closer to the elevated temperatures (95°F / 35°C) materials were exposed to in the testing and laboratory scenarios. This abruptly catapults a forecast and assessment into the lived reality of millions. This highlights the importance of understanding these correlations and taking action. 

Additional Definitions:

¹ Hygrothermal refers to the effects of heat and moisture within buildings.

² Adsorption refers to VOCs adhering to the surfaces of porous materials within a space.

Deposition refers to how particles move and attach to surfaces within a space once emitted from an indoor source.

Resuspension refers to previously settled particles reentering airways due to a disturbance. 

In Coagulation, particles collide and stick together resulting in increased particle size. buildings.

³ Redlining refers to government-implemented discriminatory housing maps from the 1930s, which labeled areas with Black residents as undesirable and risky for investment.