Doug Quattrochi

In case you missed it, your unvented gas stove may be slowly debilitating you and your customers. “Surely I would have noticed,” I can hear you thinking. But alas, small injuries that add up over long time can be unnoticeable. As an asthmatic with a long history of unvented gas stove use, allow me to shed some glowing blue light on the subject. 

Before I begin, let me acknowledge the awesome utility that is natural gas. For over a century, most of us in Massachusetts have both cooked and heated our homes with this reliable, affordable, soot-free fuel. Our gas appliances rarely need tuning or repair. Gas has been an historically cheap energy source. And gas has burned clean, in the sense that we don’t get much of the carbon soot that wood and oil produce. 

Unfortunately, the tide of knowledge that swept away fireproof asbestos and durable lead is rising over natural gas. Natural gas is a mixture of primarily methane but also other combustible chemicals. It’s a 19th century technology with 21st century branding. Methane, as I’ll refer to it going forward, is dangerous in three ways.  

First, methane detonates over a range of fuel-air mixtures – remember the Merrimack Valley explosions in 2018? Second, unburned methane is a potent greenhouse gas, responsible for one-third of short-term global heating. New research published in the Journal of Environmental Science & Technology now identifies idle gas stoves as emissions sources equal to 500,000 cars. In other words, stoves leak even when not in use.  

But most of all, burned methane is not as clean as we once believed. 

Methane Byproducts Damage Young Airways 

When methane is burned on a stove, it burns lean, meaning there’s a lot more air than gas. This allows a totally separate reaction from the combustion to take place, in which hot nitrogen present in the air bonds with hot oxygen to form nitrous oxides, or NOX. The most common NOX is NO2, which punches holes in the ozone layer and in kids’ airways. 

In 1992 a meta-analysis by scientists Vic Hasselblad, David Eddy and Dennis Kotchmar showed that long-term exposure to NOX creates a 20 percent increased risk in all respiratory illness, including cold and asthma, among children. Twenty percent isn’t a lot for an individual, but it’s enormous for a society.  

Research shows asthma is 18 percent to 48 percent more likely with exposure to methane cooking.

In 1997 the World Health Organization timidly started to incorporated NOX into its guidance on indoor air quality, setting a 24-hour limit of 75 micrograms per cubic meter. 

 “When unvented combustion appliances are used for cooking or heating, indoor concentrations of nitrogen oxides typically greatly exceed those existing outside,” the WHO wrote. “Epidemiological observations of associations between increased respiratory illness in school children and indoor and outdoor exposures to NO2 are suggestive of human health effects associated with long-term NO2 exposures.”  

In 2005, the WHO cited animal research showing “profound effects [of NO2]… in ferrets and in non-human primates… thickening of the alveolar walls, increased cellularity and collagen deposition indicative of oxidant damage.” 

In 2013, a meta-analysis by scientists Weiwei Lin, Bert Brunekreef and Ulrike Gehring showed asthma specifically was 18 percent to 48 percent more likely with exposure to methane cooking. 

Now, just as adults aren’t bothered much by lead, it looks like adults aren’t bothered much by methane stoves. A 2003 NIH study couldn’t find an impact on adults. This work is currently being reexamined at UMass Lowell.  

We have entire sets of lead laws designed to protect kids’ brains. It’s past time we had something equivalent to protect kids’ airways. 

What Should We do? 

Anyone renovating or developing should vent methane stoves outdoors. This means more than a grease filter that blows nitrous oxide back into the kitchen. Venting means air blows to the outside.  

If you can’t see how to install venting in your building, run a 30- or 50-amp line for a nice induction stove and cap the methane line. Induction can boil water seven times faster than electric resistance and three times faster than methane. Induction is zero-NOX, zero emissions, a joy to cook on and a breeze to clean. A starter cookware set for cash-strapped renters can be had on Amazon for under $100. 

Current law clearly establishes a standard of “reasonable accommodation” for renters with a disability. If a renter asks you to vent the stove or install induction for their kid with asthma, you’d best do it. To my knowledge, this has not yet been litigated. Don’t be first. 

Finally, before the pandemic, venting was about to become law. The state sanitary code, 105 CMR 410, was under notice and comment. At that time, 410.170 was proposed to read, “All devices that combust fuel… shall be properly vented to the outdoors.” Changes to the sanitary code typically take immediate effect with no grandfathering and no deployment timeline. 

MassLandlords’ mission is to create better rental housing. To us, it’s clear that vented methane stoves are a lot better than unvented. 

Doug Quattrochi is executive director of MassLandlords Inc.