Need Another Reason to Support the Transition Away from Gas Stoves? Nanocluster Aerosols.

by Carmi Orenstein, Editor

For more than a decade, Concerned Health Professionals of New York has had our heads down in the research focused on the impacts of fracking: underground, on the surface, and in the air, in and around the fracking fields of the world. And we have brought the research results to the public, in support of the fights to stop or at least slow down this destructive practice. Meanwhile, in our own state we welcomed a ban ten years ago, and, cognizant of New York’s continued dependence on fracked gas piped in from elsewhere, joined ongoing efforts to entirely move New York to safe, renewable energy. 

In recent years we’ve recognized the stubborn role that household gas stoves have played in this policy challenge. At the same time, gas stoves continue creating toxic exposures to linked to public health scourges like asthma. Indeed, gas stoves are the fracking tailpipe in our kitchens.

The basics of these exposures and impacts have been documented in the scientific literature for a long time. For example, research from the 1970s through the 1990s showed associations between nitrogen dioxide (NO2) emitted into residences, including from gas stoves, and acute respiratory infections. Subsequent studies ironed out the details and expanded the scope, demonstrating troubling asthma impacts by a range of measures, as well as links to chronic obstructive pulmonary disease. One of the more recent studies put the contribution of gas stoves to childhood asthma into sharp focus, finding that New York state’s kids suffer an especially high burden, with 18.8 percent of their asthma cases attributable to living with a gas stove (compared to 12.7 percent nationally).

Other kinds of research demonstrate that the only real solution to mitigate this risk to anyone living with a gas stove is to remove the gas stove. NO2  in the air resulting from gas stove use is not consistently or easily reduced by mechanical ventilation (range/stove hoods). Further, replacing a gas stove with an electric one achieves NO2 reductions even if gas furnaces or gas clothes dryers remain in place. The contribution of gas stoves to poor indoor air quality is uniquely large. 

Armed with this science, the case for speeding up policies that will help make this change—especially for low-income individuals and families, renters, and all those living in environmental justice communities—is strong. What more do we need to know, scientifically? 

Meet “nanocluster aerosol”

As it turns out, there’s plenty more to know: as research findings on micro- and nanoparticles expand—what they are and where they come from, where they are being deposited, and the harms they are causing—gas stove emissions are now part of that conversation. Alarmingly, exposure to newly-identified and measured “nanocluster aerosol” (NCA), generated by gas cooking, is now identified as “a major respiratory burden for children and adults due to large doses of NCA to the head airways and tracheobronchial region.”

NCA are 1-3 nanometers (nm) in size, a nanometer being an billionth of a meter. The new study relies on previous science to characterize NCA as “likely flame-generated incipient soot particles.” 

Other prior research conducted on outdoor NCA showed that, when inhaled, NCA deposits more readily in the upper respiratory tract than other very fine pollution particles, can enter the bloodstream, and potentially find its way to other vital organs. “Due to their high surface area-to-mass ratios, NCA are associated with a heightened propensity for bioactivity and toxicity.” 

This new Purdue-University led research aimed to address the lack of data on indoor NCA and to better understand the links found between indoor gas combustion and asthma. The scientists found that, during gas cooking, indoor NCA can be found at concentrations (1–10 million NCA/cm3) much higher than concentrations created by gas or diesel vehicle emissions that have been measured outside. Residents could be breathing in 10-to-100 times more of these particles from proximity to gas stove cooking indoors than they would from breathing in car exhaust while outdoors in an urban environment. 

According to the researchers, these are very large doses. During 20 minutes of cooking, the “cumulative adult respiratory-tract-deposited doses” ranged from about 10 billion to 1 trillion deposited NCA in adult respiratory systems. They also considered differences between adults and children, via age and weight doses. They found children to have “higher weight-normalized NCA dose rates compared with adults… by about 2.3-fold for the head airways, 2.2-fold for the tracheobronchial region, and 3.0-fold for the pulmonary region.” 

They wrote that these findings constitute a “significant respiratory burden” for children and adults, and that NCA exposures may represent “a major public health concern.”

Calling it a day with indoor combustion for cooking: Moving policy forward

New data enabled by new research technologies is always welcome. (The Purdue scientists used a “novel high-resolution particle size magnifier—scanning mobility particle sizer.”) However, the precautionary tale here is age-old, ever since our ancestors made fires inside shelters: “Early humans would have been aware of at least some of the potential hazards in the air they breathed from their general discomfort in the presence of smoke and combustion gases close to open fires.” Fast-forward to our ever-expanding understanding of the specific risks and harms of bringing methane-fueled flames into the home. 

We know enough to call it a day with indoor combustion cooking. Oddly, a quarter of the way through the 21st century and, though building codes exist for ventilation of gas furnaces and dryers, “there are few overarching standards for gas stove installation and ventilation.” 

Culture wars, led by the gas industry, have ignited in the last few years as public health, renewable energy, and climate advocates have looked to accelerate the transition to safer cooking appliances. (This month, two senators have taken on the American Gas Association.) At the same time, many, including the Los Angeles Times editorial board, believe this relatively straightforward fix will indeed happen along with the healthy trend toward overall building electrification: 

The transition to all-electric buildings is so well underway that legal obstacles thrown up by the fossil fuel industry and its allies won’t be enough to stop it. The market is already moving away from gas appliances in favor of electric models. And state and local leaders still have a lot of other tools at their disposal to accelerate that trend….

With more progress than setbacks, it’s clear that gas appliances are on the way out in California one way or another. For the sake of pollution-plagued communities and future generations’ right to a safe climate, state and local officials should do all they can to make it happen quickly.

We remain committed to keeping up with the science and amplifying important findings. With data such as that showing the climate impact of gas stoves in the United States (comparable to the annual carbon dioxide emissions of 500,000 cars), to this new research on harmful nanoparticles coursing through our lungs and beyond, we’ll continue bringing the science to bear on policy debates and support forward-thinking initiatives. In this vein, I’ll be touring with Better Buildings NY next month, bringing the health and science data to community-based conversations about alternatives to gas appliances around New York State.