Resources from Oregon CUB on Gas Stoves and Indoor Air Quality

We are happy to be able to share this recent article by Amelia Lamb from the Oregon Citizen Utilities Board’s blog. It is a thorough look at the health risks of gas stoves with respect to the air quality inside our homes, and includes ways to mitigate them through proper ventilation, or remove them altogether, by replacing a gas range with an induction model. Thanks to Amelia and CUB for creating this informative resource and allowing us to share it with our community.

Gas stoves are in many Oregon households. But how safe are they, really? The short answer and big takeaway: gas stoves have been shown in several recent studies to emit many different chemical compounds that are dangerous to human health.

In today’s installment of CUB’s blog series on busting natural gas myths, we explore the health risks of gas stoves and ways to prevent unsafe levels of indoor air pollution in your kitchen.

Gas Stoves Are Big Emitters of Methane

The natural gas that powers these stoves is mostly composed of methane, a powerful greenhouse gas and climate pollutant. When the gas is burned, it produces carbon dioxide. But gas stoves also leak unburned methane into the air.

A Stanford study looked at methane emissions from gas stoves not just during use, but also while they were off. Researchers looked at a wide variety of stove brands and ages. They found that on average, the methane produced by puffs of gas during stove burner ignition was the same as that produced by ten minutes of cooking. Stoves with pilot lights were the worst emitters sampled in the study.

The researchers also found that three-quarters of methane emissions were produced while the stoves were turned off. This finding may seem shocking, but it aligns with a growing body of research. Many studies are showing that methane leaks occur throughout the natural gas system, from extraction all the way to the consumer household.

In high concentrations or lower ones over a prolonged period, methane can displace oxygen in the air inside your home. This can cause a range of symptoms from dizziness and memory loss to depression and heart problems.

And as methane builds up in the atmosphere, it increases the concentration of ozone. When inhaled, ozone constricts the airway muscles and leads to wheezing and shortness of breath. It also worsens existing respiratory conditions like emphysema, bronchitis, and asthma.

Gas Stoves Emit Other Harmful Pollutants

In addition to methane, gas stoves also emit nitrogen oxide, nitrogen dioxide, carbon monoxide, and formaldehyde. These pollutants all pose health risks and are not consistently regulated. (For example, only 27 US states require all homes to be fitted with carbon monoxide detectors. No such requirement exists for the other three compounds.)

Gas stoves also produce PM2.5 particulates at roughly twice the rate of electric stoves. PM2.5 is one of the biggest factors in air quality reporting because it is so harmful to respiratory health.

There may be many more volatile organic compounds present in the gas that powers your stove. A study published in June 2022 by the journal Environmental Science and Technology looked at levels of these dangerous compounds in samples of unburned natural gas from household gas stoves and pipes across the city of Boston. They detected the presence of 21 different volatile organic compounds that the EPA has designated as hazardous air pollutants. One of the compounds they found, benzene, has no known safe exposure level.

Gas Stoves and Child Asthma

Recent studies have shown that the respiratory health risk of living in homes with gas stoves is particularly high for children. Children are more vulnerable to air pollution than adults. They have higher breathing rates and rates of physical activity, higher ratios of lung surface to body weight, and immature respiratory and immune systems.

One of the most well-studied indoor air pollutants emitted by gas stoves, nitrogen dioxide, has been found to exacerbate child asthma. These effects have been shown at much lower exposure levels than the EPA standard for long-term outdoor exposure, and the EPA has no safety standard for indoor exposure to nitrogen dioxide.

Yet a 2020 report from Rocky Mountain Institute shared levels of nitrogen dioxide that had been measured from gas stoves during common uses such as boiling water or baking a cake. All cooking activities produced levels exceeding the EPA’s outdoor exposure standard – some by as much as 300%. Nitrogen dioxide from some gas ovens burning with no food in them was over five times the EPA outdoor exposure limit.

How to Reduce Risk with Gas Stoves

The first rule of safety for all gas stoves is to make sure knobs are turned all the way off when not in use to prevent large leaks of unburned gas. Make sure also that you have a carbon monoxide detector installed close to your kitchen, if not inside it. Test your detector at least once a year. And always replace batteries immediately when your detector chirps to indicate that battery power is low.

But how should home cooks protect their families from lower carbon monoxide levels, methane, and other harmful compounds while their stoves are in use? The key to this is making sure you have adequate ventilation.

Hoods and Fans
Some gas-powered homes have hoods or fans installed over their gas stoves. Yet surveys have shown that many home cooks who have stove fans or hoods use them infrequently or not at all. If you have a hood or fan over your gas stove, try to use it consistently, every time you cook.

Building regulations do not require residential gas stoves to be vented to the outdoors. But if you are shopping for a stove hood, CUB recommends looking for one that can vent outside your home.

Unsure if your existing stove hood vents outdoors? Look for a duct. You can check the cabinets above your stove to see if there is a duct (look for a silver tube). For a single-family home, try to locate the end of the duct to make sure it is venting all the way outside and not stopping in your attic. Most multifamily housing does not have this type of kitchen ducted ventilation.

Airflow From Windows and Electric Fans
Unfortunately, Oregon does not offer rebates or other incentives for the purchase of range hoods. And many customers cannot afford the cost of purchasing and installing one. Many others live in homes where the installation of an outdoor venting hood is made impossible by the home’s layout or not allowed by the landlord.

If your home does not have an outdoor venting stove hood, Oregon Building Codes still require some sort of ventilation in all kitchens with no exception. Any kitchen without mechanical ventilation, like an outdoor venting hood, must have a window that opens.

If installing an outdoor venting hood over your stove is not an option for you, it is extra important to air out your kitchen by opening windows. If you don’t have windows that open in your kitchen, your home is not up to code and needs to be updated.

To be extra safe, use open windows and electric fans in combination with each other, especially if you are cooking food at high temperatures or for a prolonged period of time. If the air quality outside is unsafe because of smog or wildfire smoke, avoid cooking with your gas stove if possible until the air quality in your area returns to safe levels.

Switching to an Electric Stove

If you are able to and interested in replacing your gas stove for an electric stove, you have many options. A study conducted in 2014 found that induction ranges send 85-90 percent of the generated heat directly to the food they’re cooking. In comparison, electric stovetops hover around 65-70 percent. Gas ranges come in last with about 40-55 percent efficiency. This means that more than half of the energy from a gas range is wasted. Induction ranges are the most efficient option by far.

Learn more about induction stoves on the CUB Blog.