Flames over a gas stove
 Flames over a gas stove
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Is the air in your kitchen safe?

There is fresh evidence that kitchen ranges and stovetop cooking can be hazardous to your health and indoor air quality. Learn more.

There is fresh evidence that kitchen ranges and stovetop cooking can be hazardous to your health.

Several types of air pollutants are common in homes, including mould and mildew from water-damaged bathrooms and basements, dander from pets and infiltration of outdoor traffic pollution. But often, in many homes, the kitchen is by far the most polluted room of all. The main culprit is the kitchen range and the cooking that goes along with it.

Nitrogen dioxide, formaldehyde, carbon monoxide

Cooking on a stovetop – especially a gas range – can produce high levels of nitrogen dioxide, a gas byproduct of combustion at high temperatures. Nitrogen dioxide can reduce lung function and increases the risk of other respiratory conditions such as asthma. Other gases produced by the cooking process include formaldehyde and carbon monoxide.

A new study conducted by Lawrence Berkeley National Laboratory estimated that 60% of homes in California that cook with gas at least once a week reach indoor pollution levels that would violate federal outdoor air quality standards. That would include 12 million Californians exposed to unsafe levels of nitrogen dioxide, 10 million exposed to excessive formaldehyde and 1.7 million exposed to excessive carbon monoxide.

These results are consistent with other research, such as a study released in 2012 by the University of Sheffield (U.K.) that found nitrogen dioxide levels in kitchens with gas stoves to be three times higher than U.K outdoor air quality standards. Acute or long-term exposures to these chemicals are strongly connected to the development or exacerbation of respiratory conditions such as asthma, cardiovascular conditions such as high blood pressure and heart disease, and certain cancers.

Ultrafine particles and cooking

Another danger of indoor cooking is the generation of ultrafine particles. Both gas and electric burners produce high levels of ultrafine particles, according to Berkeley Lab. Electric burners, in particular, create ultrafine particles through a process called “volatilization,” or vaporization. The process is similar to that used in toasters and electric heaters. “After you turn it on (if you haven’t used it for awhile), you can smell it – it smells terrible,” said one of the researchers in the report. “You’re smelling the chemicals that have been volatilized.”

Unlike larger particles, ultrafine particles are deposited in the lungs where they have the ability to penetrate tissue and be absorbed directly into the bloodstream. Regulations and recommendations of “safe” levels of ultrafine particles do not yet exist for indoor or outdoor air, as research is still emerging. Current kitchen ventilation systems do not adequately and consistently provide a remedy. Even high-quality range hoods that vent kitchen air pollution to the outdoors were found by Berkeley Lab to have a “capture ratio” of 80% for the back burners but only 60% for ovens and 50% for front burners. The capture ratio measures the percentage of the indoor air pollutants that are successfully removed from the indoor environment.

Air purifiers, range hoods that exhaust can help

A high-performance air purifier can make a difference in controlling kitchen air pollution, but to be effective the air purifier must be able to filter particles (especially ultrafine particles) as well as gases such as nitrogen dioxide and carbon monoxide and volatile organic compounds such as formaldehyde.

Meanwhile, the Berkeley Lab research team is recommending the use of kitchen range hoods that exhaust to the outside. Even modest improvements in levels of indoor pollutants would help significantly, they say. The Berkeley Lab team is developing test methods for a rating system to measure the effectiveness of range hoods. They also hope to see eventual progress in the development of quieter range hoods that turn on and off automatically depending on the level of pollutants in the kitchen.

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