Based on a study of a paltry 53 homes in California, researchers with Oakland-based Physicians, Scientists and Engineers for Healthy Energy (PSEHE) and Stanford University estimated that stoves emit between 0.8 and 1.3 percent of the natural gas they consume as unburned methane with three-quarters of these emissions occurring when the devices are shut off, suggesting leaky fittings and connections with gas service lines. The flawed research is to support banning natural gas appliances, as some cities in California and elsewhere have done for new buildings, as well as others debating converting existing buildings that consume natural gas to electricity, despite the extremely high costs to do so. The current study draws its conclusions by incorporating inflated methane emissions and claiming health impacts from emissions of nitrogen dioxide, a federally regulated pollutant.
There are numerous problems with the study—from sealing off the cooking room when taking measurements in their “laboratory”—to assuming that the leaks, if there are leaks, would have no odor. The following refutes their premises and conclusions.
Issue 1: The researchers set up an unrealistic environment
The researchers encased the tested kitchen area in plastic sheets, sandbags, and painter’s tape – which in no way represents the kind of kitchen in which normal people cook. Sealing the room with plastic also meant sealing any ventilation to the exterior. Instead of using the “ductless” range hoods, which many homes had, the researchers used indoor fans to circulate air at selective locations and speeds to, supposedly, not interfere with the burners. Vented hoods have a high degree of effectiveness when overhanging the stove, and their counterpart, the “ductless” range hoods, feature activated carbon filters to remove particulate matter and pollutants from recirculated air. The sealed off room and the circulating fans are not representative of how Americans cook in their kitchens. It is more akin to measuring air quality produced by automobiles by attaching a hose to a tailpipe and directing it into a closed passenger compartment of an auto.
There are also issues with natural gas stove technologies that should be taken into consideration – but were not—when doing this analysis. The researchers found that stoves with pilot lights produce larger amounts of methane because they require constant natural gas stream with delays in ignition between steady-off and steady-on states. Newer natural gas appliances, however, do not have these inefficient pilot lights. Further, as of 2009, the U.S. Department of Energy issued a “no standing pilot light” rule, which prohibited standing pilot lights in gas cooking products.
The above may be some of the reasons why in two of the scenarios—the stove steady-state-off and cooktop steady-state-on scenarios—five stoves (nine percent of the sample size) emitted half of all measured emissions.
Issue 2: Inappropriate health comparison
In order to make the claim that gas stoves are harmful to health, the researchers compared nitrogen dioxide (NO2) emissions readings over the course of a few minutes to the average one-hour outdoor National Ambient Air Quality Standard (NAAQS) for NO2. The researchers did not acknowledge that the “1-hour national standard” is an outdoor standard, and is also an average, although they do admit that “there are no indoor standards.” Thus, the research team erred by comparing a peak reading in a small sample to an average outdoor standard. It is meaningless to compare a maximum to an average.
Further, since the researchers excluded ventilation, they distorted the measurement even more. When ventilation is included, concentrations of pollutants from cooking burners are reduced by 55 percent.
Last year, a study on this same topic called out a separate research team at UCLA for making the exact same claim.
“For comparison to NAAQs and CAAQs, the UCLA Report compared peak (maximum) concentrations directly to 1-hour NAAQs and CAAQs. The comparison of maximum peak concentrations to a 1-hour standard is not correct and certainly not relevant for assessing health risks. The 1-hour NAAQS and CAAQS represent health effects thresholds associated with 1-hour time averaged exposures. It is meaningless to compare a maximum to an average.”
The UCLA study was funded by the Sierra Club and was not peer-reviewed. This same fundamental error, however, occurs in the Stanford study, which was peer-reviewed. Clearly, dishonest claims should be dismissed when researchers and reviewers cannot be honest and must rely on sleight of hand and confusion to make claims regarding gas stoves and health in pursuit of a policy goal of banning gas stoves.
Issue 3: Researchers do not understand natural gas use in homes
The authors of the study told E&E News that the “larger than we thought” gas leaks they found could be happening in homes without residents knowing it. Their reasoning was amazing:
“The leaks were probably occurring on pipe fittings located in the kitchen itself and could be too small to perceive by smell, allowing them to drag on without being detected, since methane doesn’t give off a smell, Lebel and a co-author, Stanford professor Rob Jackson, told E&E News.”
The statement makes no sense because natural gas that enters transmission and distribution lines that go into houses must be odorized as a safety mechanism. Even though methane may be odorless in its natural state, most people associate a rotten eggs smell with natural gas. The odor occurs because the utility is required by law to add mercaptan to the gas stream so residents will be able to detect gas leaks.
Equally alarming was the suggestion by one of the researchers that people should fix their fittings on their own to ensure no leaks are evident. If residents have any reason to believe they may be experiencing leaks, they should call a licensed professional. Telling people to pull out their own stove to tinker with the connectors reflects a lack of understanding of how natural gas appliances function in the home, and in fact, could lead to catastrophic accidents
Issue 4: Activist involvement
The lead author, Eric Lebel, is affiliated with PSE for Healthy Energy, an organization funded by the Park Foundation, which also supports anti-fossil fuel groups and interests across the country. Years ago the head of the Park Foundation bragged that the organization was funding an “army” to oppose fracking.
The PSEHE’s Executive Director wrote a memo in 2012 laying out a strategy for making questionable health claims about fracking.
Issue 5: The natural gas industry has actively invested in reducing emissions
According to the American Gas Association, the natural gas industry has committed to investing nearly $30 billion each year to modernize the gas system and is investing $3.8 million every day to help customers and communities reduce their carbon footprint. Pipeline replacement projects have reduced emissions from the natural gas distribution system 69 percent since 1990 as pipes that may no longer be fit for service are being replaced with ones made from more modern materials, which increases safety and reduces emissions. Natural gas utilities have offset over 13.5 million metric tons of carbon dioxide emissions from 2012 to 2018—the equivalent to removing 2.9 million cars off the road for a year.
Conclusion
While combustion emissions from gas ranges, ovens, and cooktops can contribute some emissions, there are no documented risks to respiratory health from natural gas stoves from the regulatory and advisory agencies and organizations responsible for protecting residential consumer health and safety. Federal agencies such as the Consumer Product Safety Commission and the Environmental Protection Agency closely monitor and have evaluated homes with natural gas piping and natural gas appliances and have not taken any action to limit their use due to methane emissions as this study would suggest.
Nationally, more than one-third of households—about 40 million homes—cook with natural gas. To have all these households switch to electricity would be an enormous undertaking with huge costs and massive increases in demand for more electricity. Higher energy costs force homeowners to keep their homes at unsafe temperatures and greatly impact lower income residents who do not have sufficient income to meet their basic needs, particularly amongst rising prices. Further, natural gas is the main fuel used to generate electricity in the United States. Approximately 40 percent of our nation’s electricity comes from natural gas. But using natural gas to make electricity, rather than delivering it directly to a home or business is significantly less efficient. Converting natural gas into electricity only maintains 36 percent of usable energy from production to customer. Homes that use natural gas for heating (about 50 percent of U.S. homes), cooking, and clothes drying emit 37 percent fewer total carbon dioxide emissions than homes using electricity.
Attempts to force government policy changes on the basis of flawed studies performed in unnatural conditions mislead the public, and should be called out when they are cited by proponents of such changes.
