by Dan Jaffe and Amelie Creekmore, University of Washington

In recent months, there has been a surge of concern regarding the health effects of owning a gas stove. Articles from the New York Times (see article here), as well as several other news sites, have pointed out possible risks of living with gas stoves (see statement from US Consumer Products Safety Commission).   Despite the recent surge of news, there is surprisingly little data out there and so many questions remain:  How bad is it to have a gas stove?; How do we know when the air quality is hazardous in our home?  And how can we improve our indoor air quality?  Will my stove fan protect my family if I have a gas stove?   In this blog post, we want to help you understand some of the risks for your family and let you know how you can get involved in research that will give you information about the levels of air pollutants in your home and help scientists better understand the risks.

When gas burns, the nitrogen and oxygen in the air combine to form nitric oxide (NO) and nitrogen dioxide (NO₂).   While both are hazardous, NO₂ is considered the more toxic component.  Other pollutants, like carbon monoxide (CO), also form during gas combustion.   In addition cooking food adds a host of other compounds, including PM_2.5 (particles with diameters less than 2.5 micrometers).

What are the risks of cooking with a gas stove?

A  recent study found that methane and NOx concentrations were high in homes when using a gas stove. (Lebel et al., 2022). Another study also found high concentrations of several gases and PM_2.5 when using gas stoves (Singer et al., 2017).   So why is this important? Well, a study from 2013 showed  that children in homes with gas stoves had greater risk for respiratory health problems, including asthma, mainly due to the NO₂ emitted from gas stoves during use (Lin et al., 2013). A document on the US EPA’s website summarizes some of the risks from exposure to nitrogen dioxide (US EPA 2023).

As another example, here is a real world example of how gas stove emissions impacted one family. It happens to feature my former PhD student, Prof Heather Price:

https://www.theatlantic.com/science/archive/2020/10/gas-stoves-are-bad-you-and-environment/616700/

How can I look at air quality in my own home?

A big question for you is:  how do we even know when chemical or particulate matter (PM) concentrations are getting to unhealthy levels in your home?  For particulate matter (or PM_2.5) there are several low-cost indoor air quality sensors that can monitor PM concentrations.  See our previous blog post (https://sciencenorthwest.com/living-with-smoke/).   However, getting information on NO₂ and CO (carbon monoxide) is much harder.  There are some “moderate cost” sensors that can be used in homes, but these have not been well tested.   Our team at the UW has been testing one such sensor package made by TSI (TSI AirAssure) that can measure PM_2.5 and 6 gases (SO₂, O₃, NO₂, CO, CO₂ and total VOCs).  To date, we have found that these sensors can reliably detect PM_2.5, NO₂ and CO in homes with a gas stove.  

With the TSI Air Assure, we have been conducting experiments in one home with a gas stove and a gas oven. The graph below shows NO₂ data in this home for a one month period.  In this home, we see very elevated concentrations of NO₂, levels that exceed the EPA air quality standard of 100 ppb (red line).   So far, our data suggests that use of a gas oven generates more NO₂ than just using the stovetop burners…. In addition to the gas stove, cooking of food generates a lot of other pollutants that we can detect.   

How can I improve my indoor air quality?

There are several ways you may be able to reduce your exposure to emissions from gas stoves.   One is using an overhead vent fan when the stove is on.  But not much is known about fan use.  It probably depends on the quality of the fan and its position relative to the stove or oven burners.  Another method is opening windows and allowing ventilation with outdoor air. There are also low-cost MERV-13 or HEPA filters that you can buy to decrease PM concentrations (https://sciencenorthwest.com/update-on-merv-13-and-masks-for-wildfire-smoke/  (see also paper by May et al., 2021).  Both the low cost MERV-13 filter with a box fan or the higher cost HEPA air purifiers seem to do the job on PM_2.5, but probably have no effect on NO₂.   A charcoal coated filter may help and this is something we are planning to test in the future. 

How can I get involved in research on  indoor air quality?

Our team at UW is conducting a study to look at indoor air quality.   The goals of this study are to

1. Test and evaluate a simple sensor package that can detect these important pollutants in homes.
2. Measure the concentration of NO₂, CO and PM_2.5­  in homes that have one or more risk factors for poor indoor air quality. 

Please also note two things our study will not do:

1. Identify any specific health risks.    We do not plan to ask you any questions about health effects.
2. Identify unburned hydrocarbons (eg gas leakage)

While the sensor package does have a VOC sensor (e.g. hydrocarbons), at this time we have not evaluated its accuracy for methane or propane.   So we do not expect that this study will reliably identify any VOCs from gas leakage (i.e. before combustion).   If you have concerns about possible leakage of natural gas or propane, we strongly urge you to contact your local gas supplier.   We may attempt to quantify unburned combustion products (propane and methane) in our data, but this is not a primary goal of the study.

Do you qualify for our study?

Here are the study criteria:

1. You must cook on a regular basis (at least 7 meals per week).   And here “cooking” means not just boiling water but cooking on the stove or baking in the oven. 
2. Use must use a gas stove and/or oven for your cooking.
3. You must have wifi and be willing to record some information on your cooking each day.

If you think you fit these criteria and would like to know more about the pollutant levels in your own home, please sign up at the link below.  If you are selected for the study, we will send you a sensor package to put in your home for two weeks.  The sensor package is easy to install and will send its data to us through your wifi.  During week one, we ask that you cook and do things as you normally would.   During week 2, we would like you to take all possible steps you can to reduce/mitigate indoor air pollutants.    This would include things like running your stove fan on high, using a HEPA air purifier, and/or opening windows when the air is unhealthy.   After two weeks, you will return the sensor to us so we can send it to another participants.  At the end of the study (approximately July 1 or sooner), we will send you a report on your indoor air quality.

If you are interested please go here to sign up and we will be in touch with more information:

https://docs.google.com/forms/d/e/1FAIpQLSdcVY2Qu64xcJ867Bi3DXAVkoU008Yb9T3KVdWQVzvTSPweKg/viewform?usp=sf_link

References

Lebel, E. D., Finnegan, C. J., Ouyang, Z., & Robert B Jackson. (2022). Methane and NOx emissions from natural gas stoves, cooktops, and ovens in residential homes. American Chemical Society, 56(4), 2529–25. https://doi.org/10.1021/acs.est.1c04707

Lin, W., Brunekreef, B., & Gehring, U. (2013). Meta-analysis of the effects of indoor nitrogen dioxide and gas cooking on asthma and wheeze in children. International Journal of Epidemiology, 42(6), 1724–1737. https://doi.org/10.1093/ije/dyt150

May, N. W., Dixon, C., & Jaffe, D. A. (2021). Impact of Wildfire Smoke Events on Indoor Air Quality and Evaluation of a Low-cost Filtration Method. Aerosol and Air Quality Research, 21(7). https://doi.org/10.4209/aaqr.210046

McCabe, Liam. “Should You Ditch Your Gas Stove?” New York Times, January 12, 2023, ​​https://www.nytimes.com/wirecutter/blog/dont-need-ditch-your-gas-stove-yet/

Singer, B. C., Pass, R. Z., Delp, W. W., Lorenzetti, D. M., & Maddalena, R. L. (2017). Pollutant concentrations and emission rates from natural gas cooking burners without and with range hood exhaust in nine California homes. Building and Environment, 122, 215–229. https://doi.org/10.1016/j.buildenv.2017.06.021

U.S. Consumer Product Safety Commission. (2023, January 11). Statement of Chair Alexander Hoehn-Saric Regarding Gas Stoves. [Press Release] https://www.cpsc.gov/About-CPSC/Chairman/Alexander-Hoehn-Saric/Statement/Statement-of-Chair-Alexander-Hoehn-Saric-Regarding-Gas-Stoves

U.S. Environmental Protection Agency. (2023). Nitrogen Dioxide’s Impact on Indoor Air Quality. https://www.epa.gov/indoor-air-quality-iaq/nitrogen-dioxides-impact-indoor-air-quality. Last accessed Feb. 17, 2023.