California Wants to See How Cooking With Gas Affects Indoor Air

(Bloomberg Law) -- California air regulators are taking a new look at indoor air quality, including studying emission differences between cooking with natural gas or electric stoves.

The work comes as environmental groups and cities have increasingly sounded the alarm over natural gas use in homes. Despite objections from industry, 30 California cities—including Berkeley and San Jose—have passed rules over the past year banning natural gas outright or promoting electricity as a better option for cooking, heating, cooling, and powering buildings.

The California Air Resources Board (CARB) last did a comprehensive indoor air pollution study in 2005. But two new research projects are in process or starting soon looking at pollutants in multifamily housing and disadvantaged communities. They include examining how cooking pollution moves between apartments and exposures depending on type of stove.

“We’re very interested in the indoor air quality and the issue of gas appliances,” Bonnie Holmes-Gen, Health and Exposure Assessment branch chief at the Air Board, said May 6.

Researchers have been studying risks associated with gas cooking emissions for about 40 years. The coronavirus pandemic and associated stay-at-home orders has added “new urgency to an old problem,” said Brady Anne Seals, a senior associate at the Rocky Mountain Institute, a Colorado-based research and analysis group that advocates for sustainable policies.

Nitrogen dioxide concentrations can be 50% to 400% higher in homes using gas stoves rather than electric, according to a report published May 5 that Seals co-authored about gas stove pollution that looked at studies from the past 20 years.

Increased Asthma Risk

A gas stove also can increase asthma risks by 42%, according to the study published by the Institute, Physicians for Social Responsibility, Sierra Club, and the climate group Mothers Out Front.

“It’s so challenging with invisible gasses, which become invisible issues,” said Seals, whose report recommended federal and state officials look more closely at indoor air pollution.

The 2005 CARB study listed cooking and unvented or improperly maintained appliances as contributing to carbon monoxide, particulate mater and other emissions in indoor spaces.

Increasing energy efficiency measures also mean homes and buildings are more tightly sealed, CARB spokeswoman Melanie Turner said in an email.

The CARB study that kicked off in March is looking at air quality, energy efficiency and greenhouse gas reductions in multifamily units. That would will include modeling of emissions from electric versus gas stoves and movements between housing units.

Another one beginning this fall will look at air and noise pollution in disadvantaged communities, with an eye on the types of appliances used in homes and potential differences in exposures.

“We might see a bump up in some of the pollutants when people are cooking,” said Pat Wong, manager of the Air Board’s indoor exposure assessment section.

Industry Reluctant

The natural gas industry says it is working to reduce cooking gas emissions and opposes ordering people to switch out their appliances.

The cost to consumers is also high for slight emissions reductions, said Richard Meyer, managing director for American Gas Association, which represents 200 natural gas companies.

A 2018 report by the association concluded that mandating electric use would be costly to consumers and the economy, as well as possibly burden the electric grid.

“Broadly, we are against any policy that is trying to force homes and businesses to switch out their appliances,” said Jake Rubin, the association’s spokesman. “We are in favor of consumer choice.”

Global Thresholds

Nitrogen dioxide in indoor air quality isn’t regulated federally, but thresholds have been set elsewhere in the world.

Canada has set an indoor one-hour, or short-term, exposure limit for nitrogen dioxide levels at 90 parts per billion, and the World Health Organizations set its limit at 106 parts per billion for the same duration.

For context, frying bacon on a gas stove can emit up to 104 parts per billion, Brady’s study reported.

Unlike outdoor air pollution, people can play a big part in their indoor environment and reducing contaminants. That includes using cooking ranges that vent properly, having certified indoor air cleaners, and buying cleaners that have low concentrations of volatile organic compounds, Wong said.

The C40 Cities also released a guide on indoor air pollution at the end of April, saying the reduction in outdoor pollution was good but people need to be mindful of what they’re breathing indoors, especially with more time being spent inside because of coronovirus concerns.

Tips from the group, which represents 96 cities committed to fighting climate change and working for cleaner air, included cutting back on candle and incense use, reducing use of harsh cleaners or artificial air fresheners, and having a no-smoking policy or allowing only in well-ventilated areas.

The Sierra Club has received funding from Bloomberg Philanthropies, the charitable organization founded by Michael Bloomberg. Bloomberg Law is operated by entities controlled by Michael Bloomberg.

To contact the reporter on this story: Emily C. Dooley at edooley@bloombergenvironment.com

To contact the editors responsible for this story: Gregory Henderson at ghenderson@bloombergenvironment.com; Chuck McCutcheon at cmccutcheon@bloombergenvironment.com

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