About a third of US households use gas cooking appliances; the rate is even higher in Southern California, where more than 50% of households cook with natural gas. A new study has found that their use can contribute to poor indoor air quality, particularly when used without an exhaust hood. Gas appliances emit nitrogen dioxide, carbon monoxide, and formaldehyde, each of which can cause a variety of respiratory problems and other illnesses. Researchers from Lawrence Berkeley National Laboratory and Stanford University developed a simulation model to estimate gas stoves emissions and the exposures experienced by different household members. They published their findings in the January edition of Environmental Health Perspectives.
The model employed a representative sample of Southern California households. The researchers acquired data on the homes and the occupants, including how often they cooked breakfast, lunch, and dinner. The researchers estimated air exchange rate (i.e., the rate at which outdoor air replaces indoor air), the amount of time individuals spent at home, and outdoor profiles for nitrous oxide and carbon monoxide because indoor concentrations of these two pollutants are markedly influenced by outdoor levels; in contrast, formaldehyde concentrations usually are derived from a variety of sources. The investigators assumed one adult cooked in each home and that any children aged 0–5 years would be in close proximity to the adult while he or she was cooking.
The researchers found that gas burners were estimated to add 25–33% to the week-averaged indoor nitrous oxide concentrations during summer and 35–39% in winter. The theorized that the seasonal variability was due to the fact that air ventilation is lower in winter. For carbon monoxide, gas stoves were estimated to contribute 30% of the indoor concentration in summer and 21% of the indoor air concentration in winter. In this case, the appliances contributed relatively more carbon monoxide during summer because outdoor concentrations tend to be lower during that season. Compared to other indoor sources such as furniture and building materials, gas appliances contributed minimal amounts of formaldehyde to indoor air.
The study authors suggest that increasing the use of venting range hoods could reduce indoor air pollution as well as exposures to harmful substances. Even greater reductions could be attained with improved hoods that capture pollutants more effectively, or quieter hoods that individuals are more likely to turn on. An alternative would be to exchange a gas stove for an electric appliance. Unfortunately, a switch from gas to electric will not eliminate pollutants because electric stoves emit pollutants such as especially particulate matter and acrolein.
Take home message:
This study notes that the use of a ventilating hood when cooking is a sensible choice. Although gas stoves are preferred by many, a switch to an electric appliance would contribute to clean indoor air. In view of this study, if you are upgrading appliances or moving to a new home, even if gas is your first choice, consider electric instead.