Commercial kitchen staff exposed to high levels of air pollution, study finds

Each time we enjoy a meal out or order a takeaway, someone cooks for us in a commercial kitchen. In the UK, 3.6 million people work in catering and hospitality. In the US it is estimated at close to 16 million. A first-of-its-kind study in the US has found catering staff can experience high air pollution at work – and that this can affect diners too.

Dr Drew Michanowicz, senior author of the study at non-profit research institute PSE Healthy Energy, said: “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 realisation that millions of people cook for a living for hours on end.”

The researchers measured air pollution in 27 kitchens including fine-dining and casual full-service restaurants, those serving pizza and Chinese cuisine, catering facilities and kitchens in senior-living communities, universities and schools.

Although the kitchens met US legal limits for air pollution in workplaces, nitrogen dioxide in 17 kitchens was greater than the World Health Organization (WHO) guidelines for indoor air. All of these kitchens cooked with fossil-gas or propane.

Nitrogen dioxide is a pollutant in diesel exhaust, which has led to many UK and European cities introducing clean air and low-emission zones.

Three all-electric kitchens, a full-service restaurant, a school cafeteria, and a conference centre kitchen were part of the study. These had the lowest air pollution, indicating benefits from decarbonisation in catering and ending fossil-gas combustion.

The electric kitchens also had the lowest temperatures, an obvious benefit for staff welfare.

This summer’s European heatwave forced some restaurants in the UK to cut hours or close due sweltering conditions. Christopher Galarza, a chef who worked with the researchers, said: “I’ve worked in kitchens where the heat was so intense that you would finish a shift drenched in sweat, dehydrated and physically spent.”

The study also found air pollution did not stay in the kitchen. Median concentrations in dining areas were greater than WHO guidelines for outdoor air pollution.

Dr Yannai Kashtan, first author of the study from PSE Heathy Energy, said: “It is difficult to contextualise the relative risk to diners, but as a diner in a restaurant with gas-fired appliances you may be exposed to elevated levels of nitrogen dioxide.”

One result surprised the research team. Kashtan said: “In two-thirds of the gas kitchens, we measured higher levels of pollution overnight and in the early morning, when all the appliances were off. The culprit? Pilot lights that burn 24/7, whether or not ventilation is on.”

In the UK many commercial kitchens have automatic systems that cut off gas when ventilation is not operating.

Michanowicz said commercial-grade cooking appliances were not included in US energy efficiency regulations that led to pilot lights being phased out in the residential sector. “In most full-service kitchens with multiple appliances like ranges, griddles, fryers, ovens, steamers, and broilers, upwards of 20-30 small flames may be constantly burning,” said Michanowicz.

In the study, air pollution from pilot lights spread into dining areas, increasing exposure for cleaners and other workers and the health risk for other people in multi-use buildings.