Restaurants with gas stoves and ovens are exposing workers to harmful air pollution and unsafe levels of heat, according to a new study led by California researchers.
PSE Healthy Energy, an Oakland nonprofit, and Stanford University researchers measured pollution levels and temperatures inside 27 commercial kitchens — 24 with gas cooking appliances and three fully electric.
They found 70% of kitchens with gas had lung-irritating nitrogen dioxide above federal benchmarks during work hours. Scientists also monitored temperatures in 19 of the gas-fired kitchens, and 13, or 68%, reached over 90 degrees. That is above a federally proposed high-heat trigger. The research was published Tuesday in the journal Environmental Research Letters.
None of the restaurants with all-electric kitchens had excessive pollutants or heat.
In California, the restaurant industry is a pillar of the economy. But few scientific studies have characterized the taxing conditions inside these workplaces.
The new findings underscore serious health risks faced by many of the 1.8 million people who work in food service statewide.
“It’s certainly no secret to folks working in commercial kitchens that these are intense environments full of heat and pollution,” said Yannai Kashtan, an air quality scientist with PSE Healthy Energy. “But I think this study’s big contribution is [detailing] the kinds of exposures we’re seeing in gas-fired kitchens versus all-electric kitchens, and seeing a pretty big difference.”
Researchers set up air sampling equipment in several locations in restaurants in California, Pennsylvania and New York. They collected air samples over multiple days, including during business hours and after closing.
The monitoring detected a medley of air contaminants commonly associated with burning fossil fuels.
Nitrogen dioxide, a corrosive gas and precursor to smog, was often found above the U.S. Environmental Protection Agency’s one-hour standard of 100 parts per billion. In some places, it was 10 times higher.
Carbon monoxide, an asphyxiating gas, and benzene, a cancer-causing vapor, also exceeded California’s hourly standards in several kitchens. Benzene levels spiked over 110 parts per billion in one kitchen — 14 times higher than the maximum California considers acceptable for one hour.
Concentrations were generally highest immediately beside the stove and near the updraft of the smoke-clearing ventilation hoods, where cooks and chefs are typically working. But elevated readings extended into kitchen prep stations and dining areas, likely exposing servers, dishwashers and even diners.
The results astonished Christopher Galarza, a Pittsburgh chef and electric cooking advocate, who helped design the study.
“The study has been honestly been an eye opener, Galarza said. “Since I’ve been doing this professionally, I’ve talked about the air quality things conceptually, but seeing these numbers in real time has really given me cause for alarm.”
“Chefs are the modern-day coal miners,” he said, noting the elevated benzene concentrations.
One of the study’s most surprising findings was when pollution levels reached their highest levels.
Pollution levels were high during work hours, though ventilation fans helped pull some of the harmful fumes from the kitchen. But for two-thirds of the gas-fired restaurants in the study, the heaviest pollution occurred overnight.
Researchers learned fumes accumulated in restaurants because pilot lights (small flames inside gas stoves that stay continuously lit) continued to burn gas after kitchens closed and ventilation fans were off.
Extreme heat proved to be another hazard.
Proposed federal occupational safety rules would require that when kitchens exceed 90 degrees, workers must get water and take 15-minute breaks. Yet most gas-fired kitchens exceeded that mark. The rules are intended to protect workers from heat exhaustion and heatstroke.
Ten of the 19 gas-fired restaurants recorded peak temperatures over 100 degrees, and four clocked over 122 degrees — nearly reaching Los Angeles’ highest recorded outdoor temperature.
Electric induction stovetops don’t create these sweltering conditions, Kashtan said. They use magnetic fields to heat pots and pans, rather than giving off heat to the rest of the room.
“The difference really is just is in the amount of heat that is wasted,” Kashtan said. “If [heat] doesn’t go into the pan or the food, it goes into the air. When you have a gas flame, only a fraction of that heat actually is transferred to the pan and the food. The rest is just exhausted into the room, and it has to be dealt with by the HVAC system.”
Still, many homeowners and restaurant owners have been reluctant to give up gas appliances. The California Restaurant Assn. notably opposed local ordinances that would’ve banned gas appliances in new commercial kitchens in Los Angeles and several Bay Area cities, citing added costs and a preference for traditional cooking techniques that rely on an open flame.
The association later won a lawsuit, striking down the city of Berkeley’s ordinance and halting others across the state.
Galarza said misconceptions about electric stoves are the largest obstacle to broader use. In addition to the health and safety benefits, he has tried to emphasize the precision of electric cooktops compared with gas burners.
Galarza began his culinary career 20 years ago, working up from mom-and-pop diners to a five-star resort. The intense heat and smoke exposure often caused him to feel lightheaded, dehydrated and even to vomit sometimes, he recalled.
However, it wasn’t until he became an executive chef at Chatham University in Pittsburgh that he embraced all-electric cooking. The university was transitioning away from fossil fuels as part of its sustainability plan, including some of its dining halls.
Galarza came to appreciate cleaner air, cooler environs and the way induction quickly heated cookware. He later made history, becoming the first chef to attain the American Culinary Federation’s certified executive chef designation with an all-electric kitchen.
He also started his own business, Forward Dining Solutions, to assist others build out their own all-electric kitchens. Although electric appliances cost more, he tells his clients that it’s an investment that quickly pays off, because the kitchens are easier to clean and more energy efficient.
“Every time I speak with a chef, it’s always met with hostility,” Galarza said. Then once we talk about brass tacks and how they operate their kitchen and opportunities for savings, it unanimously, it almost exclusively becomes: ‘How come we haven’t done this sooner?’”
Dining and Cooking