EPA Researchers Investigate the Impacts of Everyday Products on Air Quality
Volatile organic compounds (VOCs) are organic chemicals found in air that come from a number of natural and artificial sources such as vehicles, dry cleaning processes, cooking, and wood burning. VOCs can be harmful to human health both from direct exposure via inhalation in the vicinity of product use and from exposure to their secondary products when they react in the atmosphere to produce pollutants, like ozone and fine particulate matter (PM2.5). Health effects from direct exposure to VOCs can include eye, nose, and throat irritation, headaches and nausea, and liver, kidney, and central nervous system damage.
VOCs can enter air when they evaporate from adhesives, cleaning agents, personal care products, paints, pesticides, and other volatile chemical products (VCPs). In a recent study, EPA researchers used models to examine how VOCs from these products contribute to air pollution.
To conduct this research, EPA scientists used EPA’s Stochastic Human Exposure and Dose Simulation (SHEDS) model and EPA’s Community Multiscale Air Quality (CMAQ) modeling system. Researchers can use SHEDS to estimate chemical exposures that people encounter through ordinary activities. CMAQ combines modeling for meteorology, emissions, and air chemistry, allowing researchers and air quality managers to simulate the fate of air pollutants under varying atmospheric conditions.
EPA scientists used these modeling tools to estimate VOC emissions and the use of VCPs in southern California. This area was chosen because it regularly experiences ozone concentrations that exceed National Ambient Air Quality Standards (NAAQS) and has high concentrations of PM2.5 from organic compounds. These air quality problems are the result of emissions from a large urban area, Pacific winds pushing emissions inland, abundant sunshine that drives reactions that form pollutants like ozone and a significant portion of PM2.5, mountains forming a basin that traps air, and a layer of warm air in the lower atmosphere trapping pollutants near the surface.
The researchers were able to use CMAQ and field data to estimate how VCPs impact ozone and PM2.5 formation in the area. The results showed that VCPs are responsible for a significant portion of these pollutants. The estimates illustrated that approximately 41 percent of secondary organic aerosol (an important component of PM2.5) and approximately 17 percent of maximum summertime Los Angeles ozone concentrations came from VCPs.
EPA researchers also used SHEDS to help estimate how much VCPs contribute to the VOCs inhaled by people. The model, in combination with literature and on-site observations, showed emissions from VCPs were higher than estimated in National Emissions Inventory for California. The EPA work estimated that human exposure to VCPs by way of inhalation is more important than previously thought. Prior research indicated that inhalation of VCPs in residential environments was responsible for about 0.2 percent of a person’s average intake of chemicals. This study, however, estimates that inhalation contributes ten times that, about two percent.
Dr. Havala Pye, EPA’s leading researcher on this work, says, “This work highlights the benefits in connecting multiple scales of exposure together. The same products that result in direct inhalation also contribute to ambient pollution. By leveraging information at one scale, we can improve estimates at another. We are continuing to improve estimates of VOC emissions from volatile chemical products (VCPs) with a goal of improving the 2020 National Emissions Inventory.”
This work demonstrates that VCPs have a role in the formation of ozone and PM2.5, and direct inhalation exposure to VOCs. Previous findings have likely underestimated their impact. Secondary organic aerosols from VCPs in CMAQ are underestimated and will require an updated chemical mechanism and emissions inventory to ensure more accurate exposure estimates. EPA continues to improve methods to estimate emissions from VCPs and new methods in development are planned for the next version of the National Emissions Inventory.
Learn More
- Criteria pollutant impacts of volatile chemical products informed by near-field modeling https://rdcu.be/b76hV
- Behind the Paper: Understanding how everyday products impact air quality. https://sustainabilitycommunity.springernature.com/posts/understanding-how-everyday-products-impact-air-quality
- National Emissions Inventory https://www.epa.gov/air-emissions-inventories/national-emissions-inventory-nei
- Stochastic Human Exposure and Dose Simulation (SHEDS) to estimate human exposure to chemicals https://www.epa.gov/chemical-research/stochastic-human-exposure-and-dose-simulation-sheds-estimate-human-exposure
- CMAQ: The Community Multiscale Air Quality Modeling System https://www.epa.gov/cmaq
- Health Effects of Ozone Pollution https://www.epa.gov/ground-level-ozone-pollution/health-effects-ozone-pollution
- Health and Environmental Effects of Particulate Matter (PM) https://www.epa.gov/pm-pollution/health-and-environmental-effects-particulate-matter-pm
- Reactive organic carbon emissions from volatile chemical products https://acp.copernicus.org/articles/21/5079/2021/