What's up, Doc? Gas stoves emit pollutants that can lead to asthma

Q: Can my gas stove really make my kids sick with asthma, or is this just hype?

A: Burning hydrocarbons release potentially toxic pollutants.

This is true for cars burning gasoline; having your car run in a garage can cause a buildup of carbon monoxide and kill you. And, of course, we all know about the emissions causing the global warming crisis.

Natural gas is also a hydrocarbon, so it should not be surprising that the nitrogen dioxide, carbon monoxide, formaldehyde and other tiny airborne particles (fine particles smaller than 2.5 microns in diameter called PM2.5s) emitted from using gas stoves (which are present in about one-third of all U.S. households) can cause potential problems.

Dr. Jeff Hersh
Dr. Jeff Hersh

In addition, one study that evaluated 52 homes with gas stoves found that all the stoves leaked some methane gas and other volatile organic compounds (VOCs) even when turned off.

So no, this is not just hype.

So why has the concern about this seemingly come up out of nowhere? The short answer is this has not come out of nowhere; it has been known for decades that gas stoves emit pollutants. Many local governments (for example, Los Angeles and New York) already mandate that new homes and businesses use electric appliances rather than gas, even though many states have outlawed such bans.

However, concern about this issue has recently been highlighted by recent research that has noted just how strong the association between gas stoves and certain conditions, particularly asthma, is. One recent study noted that motre than 10% of all childhood asthma may be attributable to gas stove use. And having a gas stove for cooking was shown to increase the risk of a child in the household having asthma by more than 40%.

Because it's the emissions from gas stoves that cause the problems, it seems logical to consider actively ventilating them when they are used (ventilation is mandated for gas furnaces, but not for gas stoves), and this has also been studied. Although active ventilation of gas stoves will not completely remove the risk (and would not address the gas leakage when they're off), studies have shown that appropriate ventilation (discussed in more detail below) can reduce the risk by up to 60%.

So, what is the best way to address this issue?

  • For new homes, people should simply consider going with electric appliances.

  • For homes that already have gas stoves, or for people who really want to use gas for cooking in their new home, having a ventilation system for the stove can help minimize (but not completely remove) the risk.

If the decision is made to utilize ventilation, there are a couple of factors to consider:

  • The strength of the ventilation system needed (how many cubic feet per minute, CPM, it vents) will depend on the size of the gas appliances (how many burners, the size of the oven, etc.) and the size of the kitchen and home.

  • When possible, ventilation should be to the outside the home. If this is not feasible (for example, as in some apartments), then an appropriate high-efficiency particulate air (HEPA) filter with carbon fibers should be utilized. Simply pumping the air around within the home is not adequate.

The turnover of air in a home (the number of air changes per hour) is variable, but it is recommended by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) to be at least 0.35 changes per hour (and not less than 15 CFM). Many newer homes are designed to approach this minimum air exchange rate in order to be more energy efficient, but even old homes have some limitation of "passive" air flowing back into them. So, the proper design of a ventilation system should also consider the need for "make up" air (air to replace what is vented outside). This is even required by many building codes when a ventilation system moves more than 400 CFM.

Jeff Hersh, Ph.D., M.D., can be reached at DrHersh@juno.com.

This article originally appeared on MetroWest Daily News: Dr. Jeff Hersh addresses gas stoves and link to asthma