Levels of all carbon monoxide and formaldehyde were generally low after cooking, but levels of NO2 in post-cooking indoor air exceeded the legal limits set for NO2 in outdoor air by the Environmental Protection Agency and by California's Office of Environmental Health Hazard Assessment. "If you exceed these limits in outdoor air, there are legal repercussions—legal actions are required to clean the air," says lead study author Jennifer Logue, PhD, research scientist at the Lawrence Berkeley National Laboratory. "And in our homes, we're actually exceeding these standards."
No public-health agency sets limits for indoor air pollutants, yet NO2 can make you more sensitive to things you're already allergic to, such as pet dander, and regular exposure can lead to wheezing, asthma, and other respiratory problems.
Even people with electric stoves aren't immune. "Heating food and oil by any means is a source of pollutants, so you can't really assume you're good to go if you have an electric stove," Logue says.
Logue is part of a team of researchers at Lawrence Berkeley National Laboratory who are researching ventilation hoods and developing standards that make them more efficient at removing both grease and pollutants. Right now, ventilation hoods can qualify for the EnergyStar certification program, but that doesn't measure how effective they are at removing lung-damaging gases from your air. Her team is working on developing a national standard that would measure what percentage of pollutants is removed by the hood.
Even if you do have a powerful ventilation hood, it's not going to do you much good if it doesn't vent to the outdoors. While some states, such as California, require that they do vent outside, other states don't. So you may have what's called a "recirculating" range hood in your home; those draw air off of the stove, trap grease, and then pump the gas-filled air back into your kitchen.
What to do? "We certainly don't want to freak people out," Logue says. "But you have to think of it like the seatbelt in your car. You take reasonable precautions while driving, so you should also take reasonable precautions while cooking."
If you have a hood that vents to the outdoors but seems wimpy, use it anyway, says Logue. Her study found that even poor hoods removed some pollutants from the air, and some is better than none. Also, cook on your back burners. When hoods are installed, she says, they usually aren't lined up with all four burners on a cooktop, but "if you're cooking on your back burners, you're cooking directly under your range hood, and it's more effective."
If you're in the market for major renovations, consider an induction cooktop. While you'll still need to contend with pollutants released from food and hot cooking oils, as you would with an electric stove, induction stoves utilize magnetic energy to heat pots and pans. You get the fine control of heat that gives natural gas stoves the edge over electric coils, but you don't have to contend with noxious combustion by-products.