Energy Blog: How Dangerous Are Gas-Powered Appliances?
Some 75 million households in the U.S. rely on natural gas for space heating, clothes drying, or cooking fuel, according to the U.S. Energy Information Administration (EIA), which last conducted a national survey in 2020. For single family, detached houses – the “American home” of the popular imagination – the figure climbs to 65 percent, with 58 percent relying on a gas furnace for their primary source of indoor heating and 40 percent using gas stoves.
That’s a lot of built-in support for natural gas appliances. And in some regions, the concentration is even higher. In the Mid-Atlantic region 56 percent of kitchens have gas stoves, while 75 percent of households in the Mountain North (a region that extends from Colorado to Utah) have gas furnaces. Imagine telling all these folks they should redo their kitchens and utility rooms.
But that’s the message of a recent report from Rewiring America, a nonprofit devoted to cutting carbon emissions through the greater adoption of electric appliances and vehicles. The report, “Breathe Easy: Household electrification as a public health intervention to improve outdoor air quality,” puts a spotlight on a sometimes-hidden problem with fuel-fired indoor appliances—the pollution produced by combustion in water heaters, clothes dryers, and furnaces.
(Stoves and ovens were not covered in the report. Previous studies have indicated gas appliances in kitchens could be a health hazard.)
Products of combustion include nitrogen oxides and volatile organic compounds, both of which are harmful in large exposures, but the Electrifying America report zeroes in on particulate matter less than 2.5 micrometers in diameter, or PM2.5. “PM2.5 is especially dangerous because it can enter into a person’s lungs, and in some cases can even make its way into the bloodstream,” the report stated. “Research has shown that breathing in particulate matter can lead to a range of negative health outcomes, including cardiac events, respiratory issues such as asthma, and even premature death.”
The proposed replacements dryers, water heaters, and space heaters are based on heat-pump technology, which are electric-powered machines that use the compression and expansion of refrigerants to move heat from one side of a divide (such as an exterior wall) to another. Heat pumps are very efficient compared to the simple burning of fuels. And because they are electric, their operation doesn’t produce fine particulates and other indoor pollution.
According to the study, replacing gas appliances with ones based on heat pumps would lead to 3,400 fewer premature deaths per year and result in $40 billion in annual health cost savings. The vast majority of the impact was from swapping furnaces for heat pumps for space heating.
Natural gas producers and distributors took issue with the findings. In an article on the study published by the New York Times, a spokesperson for the American Gas Association argued that gas appliances were cheaper and that there was no significant increase in asthma risk from home gas use. According to the Times, “The group’s research found that high-efficiency natural gas appliances could yield fewer greenhouse gas emissions compared to an all-electric household and said that reductions in greenhouse gas emissions were similar to that of a heat pump in a colder climate.”
Rewiring America hopes that the value of reduced indoor air pollution will be part of the calculus when policymakers consider subsidies and rebates for installing heat pumps, such as a successful program in Maine. “Cost-benefit analyses for future electrification rebates or investments should include the potential impacts of improved outdoor air quality, in addition to benefits in the forms of reduced carbon emissions, lower energy bills, and more comfortable households,” the report concluded.
Jeffrey Winters is editor in chief of Mechanical Engineering magazine.
That’s a lot of built-in support for natural gas appliances. And in some regions, the concentration is even higher. In the Mid-Atlantic region 56 percent of kitchens have gas stoves, while 75 percent of households in the Mountain North (a region that extends from Colorado to Utah) have gas furnaces. Imagine telling all these folks they should redo their kitchens and utility rooms.
But that’s the message of a recent report from Rewiring America, a nonprofit devoted to cutting carbon emissions through the greater adoption of electric appliances and vehicles. The report, “Breathe Easy: Household electrification as a public health intervention to improve outdoor air quality,” puts a spotlight on a sometimes-hidden problem with fuel-fired indoor appliances—the pollution produced by combustion in water heaters, clothes dryers, and furnaces.
(Stoves and ovens were not covered in the report. Previous studies have indicated gas appliances in kitchens could be a health hazard.)
Products of combustion include nitrogen oxides and volatile organic compounds, both of which are harmful in large exposures, but the Electrifying America report zeroes in on particulate matter less than 2.5 micrometers in diameter, or PM2.5. “PM2.5 is especially dangerous because it can enter into a person’s lungs, and in some cases can even make its way into the bloodstream,” the report stated. “Research has shown that breathing in particulate matter can lead to a range of negative health outcomes, including cardiac events, respiratory issues such as asthma, and even premature death.”
Heat pump benefits
The report started with a previous study, the National Emissions Inventory published by the U.S. Environmental Protection Agency, that quantified the pollution from indoor combustion appliances that showed the negative health impacts of the pollution. It then added data from the EIA on the prevalence of these appliances nationally to not only put a price tag on the benefit from switching to electric units, but also how these benefits varied by state. Since 75 percent of the benefit of electrification comes from replacing gas furnaces with heat pumps, most of the regional benefit is centered in the Northeast, which combines many home heating days with a relatively large dependence on gas heat.The proposed replacements dryers, water heaters, and space heaters are based on heat-pump technology, which are electric-powered machines that use the compression and expansion of refrigerants to move heat from one side of a divide (such as an exterior wall) to another. Heat pumps are very efficient compared to the simple burning of fuels. And because they are electric, their operation doesn’t produce fine particulates and other indoor pollution.
According to the study, replacing gas appliances with ones based on heat pumps would lead to 3,400 fewer premature deaths per year and result in $40 billion in annual health cost savings. The vast majority of the impact was from swapping furnaces for heat pumps for space heating.
Natural gas producers and distributors took issue with the findings. In an article on the study published by the New York Times, a spokesperson for the American Gas Association argued that gas appliances were cheaper and that there was no significant increase in asthma risk from home gas use. According to the Times, “The group’s research found that high-efficiency natural gas appliances could yield fewer greenhouse gas emissions compared to an all-electric household and said that reductions in greenhouse gas emissions were similar to that of a heat pump in a colder climate.”
Rewiring America hopes that the value of reduced indoor air pollution will be part of the calculus when policymakers consider subsidies and rebates for installing heat pumps, such as a successful program in Maine. “Cost-benefit analyses for future electrification rebates or investments should include the potential impacts of improved outdoor air quality, in addition to benefits in the forms of reduced carbon emissions, lower energy bills, and more comfortable households,” the report concluded.
Jeffrey Winters is editor in chief of Mechanical Engineering magazine.
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