Top Four Things to Know About Sierra Club-funded Report on Air Quality & Natural Gas

There is a growing push to electrify everything recently that’s being led by “Keep It In the Ground” (KIITG) groups eager to decrease natural gas demand to prevent further development of the resource. The latest example of this comes in the form of a Sierra Club-funded report that claims residential gas appliances significantly contribute to indoor and outdoor pollution, impacting human health. Given the report’s backers include KIITG groups like Sierra Club, National Resources Defense Council, Physicians for Social Responsibility and the Rocky Mountain Institute, it’s unsurprising that the report calls for all people to replace their natural gas appliances with electric-powered alternatives.

Instead of doing their own research, the non-peer-reviewed report, conducted by the University of California Los Angeles Fielding School of Public Health, condenses stale literature on both indoor and outdoor emissions from residential appliances, focusing on California, to make its claims. However, the researchers acknowledge several important limitations and as a result, the report is littered with unsubstantiated claims.

Here are the top four things to keep in mind when reading the report:

#1 No Sampling Was Conducted

The researchers acknowledge that they “did not conduct any primary data collection” and instead relied entirely on “existing literature and datasets.” This is problematic for a variety of reasons, including that it prevented researchers from being able to quantify important metrics like the frequency of use for these appliances:

“Due to the lack of existing data sources, we were unable to quantify the frequency of occurrences of the use of kitchen appliances for heating residential spaces, or the frequency of improper ventilation that results in pollutant spillage to the indoor environment.” (emphasis added)

In other words, any estimates are based on assumptions because the researchers had no idea how often appliances were being used, nor did they know if each use was improperly vented creating indoor air quality issues. As EID has previously explained, proper ventilation is recommended for any appliances, whether they are electric or natural gas-powered.

#2 Emissions From Natural Gas Appliances Have Improved

 In order to measure indoor air quality, the researchers built an Emissions Factor (EF) model, based on pre-existing data, that allowed them to calculate which appliances emitted the most. However, they concluded that emissions from gas-fired appliances have improved considerably:

 “The EF of gas appliances have declined over time, likely due to the technological advances of appliances and pollutant capture technology, which reduce emissions”.

In fact, in terms of carbon monoxide, the report acknowledges that “(prior) research has found that CO is a lesser potential health concern […] if appliances are operating properly”. Without sampling, are the researchers thus assuming that these appliances are not operating properly?

The report fails to incorporate as part of its base assumptions the key role technological advances have played – and will continue playing –in lowering emissions and improving indoor air quality at homes.

 #3 Researchers Did Not Compare Emissions of Natural Gas and Electric Appliances

Throughout the 68-page document, researchers compiled and reviewed multiple data that suggested that natural gas appliances represented a risk to households and public health, hence recommending the complete electrification of appliances. Yet, the researchers did not conduct an equally comprehensive analysis of the risks and dangers of electric-based appliances:

“We also did not assess any exposures or other dangers associated with electrification, as we focus on combustion pollutants in this report.”

This is one of the most problematic limitations of the entire report as the researches presented this document as a guideline to policymakers without fully understanding, nor assessing the full impact associated with residential electrification.

Ironically, they acknowledged that even if all California households transitioned to electric appliances, the power source would still rely heavily on natural gas as it “accounts for approximately half of all electricity generation in California” and hence “gas usage would increase” in the state.

#4 Researchers Acknowledge That Electrified Appliances Wouldn’t Really Make a Difference

The cherry-on-top of the limitations/biased assumptions of the report is researchers admitting that regardless of using gas-fired or electric appliances, emissions would persist:

“Finally, there are indoor air quality issues associated with the use of gas cooking appliances that will remain despite the implementation of electrification, and we do not account for this. Some PM emissions are associated with cooking oils and foods, and there are no mitigation methods for this, other than the use of ventilation devices such as range hoods. We do not claim that the transition to electric appliances would make a substantial difference in terms of emissions from cooking oils and food.”

In other words, electric appliances do not solve the issue of indoor air quality because there are more variables and factors that naturally contribute to emissions generation, such as cooking methods or types of food used. The report does advise that an adequate use of the existing technology, such as ventilation devices, could help to ameliorate indoor air quality.


Objective, impartial analysis is crucial to continue developing and implementing advanced regulations and adequate public policies that guarantee the highest safety standards for our communities in relation to the energy industry.

As EID has previously noted, natural gas has improved indoor air quality in communities that have traditionally used wood or biomass and is more efficient than its electric counterparts. This report fails to acknowledge the benefits achieved through natural gas, including reliable and affordable energy for everyone, instead providing a misleading analysis based on single-handed data points and biased assumptions.

Thus, this “report” has considerable methodology and structural limitations, including the lack of existing data sources and other factors, such as appliance use frequency and seasonality.  The result is an irresponsible and inadequate effort to deter policymakers and other energy regulators away from the use of natural gas.

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