Carbon monoxide (CO), nitrogen dioxide (NO2), and particulate matter (PM) are harmful air pollutants that pose significant short- and long-term health risks. Emitted from coal-fired power plants, vehicle exhaust pipes, and other combustion sources, they’re among six primary pollutants monitored by the U.S. Environmental Protection Agency (EPA) through the Clean Air Act. These same pollutants are also some of the most common contributors to unhealthy air inside U.S. homes, due in part to a ubiquitous and possibly surprising activity: cooking.
Researchers now understand that the process of cooking food and even simply operating stoves—particularly gas appliances—can emit a cocktail of potentially hazardous chemicals and compounds. Within our homes, these pollutants are less diluted than they are outdoors, and in the absence of proper ventilation, they often are trapped inside. The World Health Organization has established general guidelines for indoor air quality and is currently developing specific limits related to burning solid fuels for cooking and heating. However, indoor air in nonindustrial buildings is not regulated by the EPA or any other U.S. agency.
“Literally millions to many millions of people are routinely being exposed to air pollutants at levels that we don’t allow outdoors,” says Brett Singer, a staff scientist at Lawrence Berkeley National Laboratory (LBNL) who studies indoor air quality and cooking emissions in particular. His team modeled gas stove emissions and exposures in California households and estimated that during a typical winter week—when windows are more likely to be closed and air exchange lower—1.7 million Californians could be exposed to CO levels that exceed national and state ambient air quality standards, simply by cooking on gas stoves without the use of a range hood. Twelve million could be exposed to excessive levels of NO2.
“That’s a lot of people in California, and those results ballpark-apply across the country,” Singer says. “The EPA would say we don’t have a carbon monoxide or nitrogen dioxide problem in this country,” he says, since average outdoor concentrations nationwide fall well below the agency’s safety standards. “In reality,” he adds, “we absolutely do have that problem; it’s just happening indoors.”
The solution offered by experts is certainly not to stop cooking. Rather, improved ventilation and filtration, achieved through better-designed range hoods and more robust building codes and standards, could ensure occupant safety by removing these pollutants from indoor air. In the meantime, experts recommend a few simple strategies to reduce exposures.