This is a part of a series about gas stoves and indoor air quality. You can read Part Two here.
In the last year there have been dozens of high profile media stories about the negative health effects of natural gas cooking.
The Atlantic published a story titled, “Kill Your Gas Stove.” David Roberts wrote this lovely and totally nerdy summary of a study published by RMI, Mothers Out Front, and Sierra Club. And more recently NPR ran a story that got a lot of attention.
The gist of every story is this: Gas stoves produce pollutants like PM2.5, NO2, and CO. And while the EPA regulates these emissions outdoors, they don’t regulate them indoors. A growing body of research suggests that this indoor air pollution leads to higher rates of asthma, heart disease, and other illnesses.
Last summer when I first read some of the stories and research studies on this topic, I have to admit that I was skeptical.
As a climate hawk, the first lens I looked at the research through was carbon emissions (and methane as a CO2 equivalent). And from that angle, gas cooking isn’t a big deal.
35% of households use natural gas to cook. In those homes it only accounts for 3% of natural gas use. That means gas cooking is responsible for ~6 million tons of carbon emissions per year. That’s 0.12% of our country’s total and only 0.6% of total home energy emissions.
In other words I thought there were bigger fish to fry (no pun intended).
I also worried that in going after an appliance that is popular, the climate community would risk backlash. And that backlash might prevent progress on getting rid of appliances that people don’t really have many opinions about, like furnaces and water heaters, which use 33 times more gas than stoves.
This summer that skepticism began to fade.
It’s not about the carbon emissions
In early August, wildfires ripped through the Western United States. As a result the front range of Colorado — where I live — recorded the worst air quality of any city in the world. Worse than Delhi, Beijing, and Katmandu.
As the air quality worsened I began to feel miserable, as if I caught a bad cold. My head hurt, my throat hurt, my entire body hurt. After a few days I went to get a COVID test. It came back negative.
Fortunately my wife and I had a trip planned to Maine. On our first day in the cleaner air I woke up feeling perfectly fine. It was clear the smoke made me sick.
Over the next few weeks, I went down a series of research rabbit holes, reading every paper I could find on the impact of air quality on human health (as one does).
One study shocked me. Using millions of Medicare records, a group of researchers found that people living in places with bad air quality (zip codes with annual average PM2.5 levels of 12 μg/m3) basically lost a year of life expectancy compared to those living in places with better air quality (annual average PM2.5 levels of 7.5 μg/m3).
One night as I read these studies in my dining room, I made the connection. I looked over at our natural gas stove and it dawned on me: this thing is slowly killing me.
How to understand risk
Still I had reasons to be skeptical.
Most studies on the association between life expectancy and air quality focused on outdoor air pollution. They focused on the impact of increased annual average exposures. But if I live in a city with good air quality and expose myself to bad air quality for 30-60 minutes 3-5 times per week when I cook, how does that affect the annual average?
The studies that did measure indoor air quality made claims like this: “Homes with gas stoves have a 42 percent increased risk of experiencing asthma symptoms (current asthma), a 24 percent increased risk of ever being diagnosed with asthma by a doctor (lifetime asthma), and an overall 32 percent increased risk of both current and lifetime asthma.”
At first that sounds terrifying. It’s easy to misread it as “People living in homes with gas stoves have a 24% chance of being diagnosed with asthma.” Statistics are frustratedly easy to misunderstand like that.
But, in fact, homes with gas stoves result in a 24% increase in the relative risk. I don’t know about you, but I don’t have a clue what the absolute risk of getting asthma is off the top of my head. That makes assessing the absolute risk (the thing we should really care about) difficult.
Let’s say the odds of being diagnosed with asthma are 1 in 10. If you live in a home with a gas stove, now your odds are 1.24 in 10. That’s 2.4 percentage points of increased absolute risk. To me that feels like a lot.
But now let’s say the odds of being diagnosed with asthma are 1 in a 1,000. Living with a gas stove increases your odds to 1.24 in 1,000. That’s 0.024 percentage points of increased absolute risk. That doesn’t stress me out as much.
Unfortunately none of the stories I read came with that important detail.
But even if I was convinced that my gas stove had to go, there was another problem, a logistical one: How do I replace it?
As with any other decision in the Anthropocene, this one would come with many options. Do I go with induction or electric resistance? A high end model or the cheapest one? Where do I even buy a stove?
Into the rabbit hole I go
Sometimes I wonder what it would be like to not obsess over these types of questions. To just read the article, call the appliance company, and install an induction range. Or to just shrug my shoulders and fire up the gas stove.
But this is not how my brain works.
And so I write to you, dear email subscriber, from deep within this rabbit hole. My home is full of air quality monitors. Our kitchen has become a lab. And my inbox is full of messages from environmental epidemiologists, a profession I didn’t even know existed before this project began.
In the next installment of this series I plan to share the results from my at-home air quality experiments.
In the meantime, I’d love to hear from you. What would you like to know about gas cooking and air quality? If you’ve read the stories I referenced above, what’s stopping you from ditching your gas stove?
Update: You can read Part Two here.