Though research has found that the presence of gas stoves in the home is one source of elevated risk of CO poisoning, that generally only happens when something goes wrong: a gas stove with a pilot light, a poorly ventilated space, a burner left on, something like that. Among average people, symptoms start at around 70 parts per million (ppm).

However, research shows that low-level CO exposure can exacerbate cardiovascular illness among people with coronary heart disease and other vulnerable populations. California’s ambient air quality standards cap CO exposure at 20 ppm over a one-hour period or 9 ppm over an eight-hour period.

“In homes without gas stoves, average CO levels are between 0.5 and 5 ppm,” the report says. “Homes with gas stoves that are properly adjusted are often between 5 and 15 ppm, whereas levels near poorly adjusted stoves can be twice as high: 30 ppm or higher.” Poorly adjusted stoves — incompletely burning fuel, inadequately ventilated — may yield ongoing, low-level CO exposure, putting the vulnerable at greater risk.

As I said, something must be wrong to produce CO