A new study from the United States reveals that air pollution in commercial kitchens cooking with gas frequently exceeds World Health Organization (WHO) safety limits. The research indicates that nitrogen dioxide levels in these environments pose significant health risks to both culinary staff and the diners they serve.
Dr. Drew Michanowicz, senior author of the study at the non-profit research institute PSE Healthy Energy, noted that while residential gas cooking is known to degrade indoor air quality, the impact is magnified in professional settings. “I was motivated by what we have learned over the years about what just 30 minutes of gas cooking can do to air quality in homes with the realization that millions of people cook for a living for hours on end,” he said.
Nitrogen dioxide levels in commercial kitchens
Researchers measured air quality in 27 different kitchens across the US. The sites included fine-dining establishments, casual full-service restaurants, pizza and Chinese cuisine outlets, catering facilities, and kitchens in senior-living communities, universities, and schools. All of the kitchens that exceeded WHO indoor air guidelines cooked with fossil gas or propane.
Although these kitchens complied with US legal limits for workplace air pollution, 17 of the 27 sites recorded nitrogen dioxide concentrations higher than WHO recommendations for indoor spaces. Nitrogen dioxide is a common pollutant found in diesel exhaust, leading many UK and European cities to implement clean air zones to protect public health.
The study also highlighted the benefits of switching to electric equipment. Three all-electric kitchens, including a full-service restaurant, a school cafeteria, and a conference center kitchen, recorded the lowest air pollution levels. These electric sites also maintained lower temperatures, offering a direct welfare benefit to workers. Christopher Galarza, a chef who collaborated with the researchers, described the physical toll of working in hot gas kitchens. “I’ve worked in kitchens where the heat was so intense that you would finish a shift drenched in sweat, dehydrated and physically spent,” he said.
Pilot light emissions and diner exposure
Perhaps the most surprising finding was that pollution did not remain contained within the kitchen. Median nitrogen dioxide concentrations in dining areas exceeded WHO guidelines for outdoor air pollution. Dr. Yannai Kashtan, the study’s first author, warned that diners in restaurants with gas-fired appliances face elevated exposure risks.
The research team discovered that in two-thirds of the gas kitchens, pollution levels were actually higher overnight and in the early morning, even when all cooking appliances were turned off. The source of this persistent emission was pilot lights. These small flames burn continuously 24 hours a day, regardless of whether ventilation systems are active.
Dr. Michanowicz explained that commercial-grade cooking appliances are exempt from US energy efficiency regulations that have phased out pilot lights in residential sectors. In a typical full-service kitchen with multiple ranges, griddles, fryers, ovens, steamers, and broilers, between 20 and 30 small flames may be burning constantly. These emissions spread into dining areas, increasing exposure for cleaners and other workers, as well as posing health risks to people in multi-use buildings.
In the UK, many commercial kitchens utilize automatic systems that cut off gas supply when ventilation is not operating, a safeguard not universally present in the US sites studied. The findings underscore the potential health advantages of decarbonizing the catering industry and ending the combustion of fossil fuels in food service environments.
Source: The Guardian
