A study published in the journal Environmental Science and Technology discovered at least 12 hazardous air pollutants emitted by gas stoves in California, including benzene — a chemical known to cause cancer in some people who are exposed to it for an extended period of time.

The study's authors, a group from the nonprofit energy research institute PSE Healthy Energy, collected gas samples from 159 residential stoves in 16 counties across California. Benzene was found in 99% of the samples.

They also calculated benzene exposure in a household based on the size of the kitchen, the level of ventilation in the room, and the amount of the chemical present, in addition to whether the stoves were leaking when they were turned off.

It is worth noting that the results showed that the leakiest stoves exposed people to indoor benzene concentrations up to seven times the safe exposure level specified by the California Environmental Protection Agency.

Although scientists are still learning about how benzene affects health, such exposure may increase a person's risk of blood disorders or reproductive issues over time. The chemical has been overwhelmingly linked to leukemia, and multiple myeloma, not to mention non-Hodgkin lymphoma. 

According to the World Health Organization, there is no safe level of benzene exposure when it comes to cancer risk. However, benzene is not the only dangerous chemical emitted by stoves, nor are the emissions limited to California. Decades of research have indicated that gas stoves also contribute to indoor air pollution.