Nine months ago, residents of the Chicago suburb of Willowbrook, Illinois, scored a major victory in their fight to prevent emissions of a dangerous gas, ethylene oxide, into the air they breathe. In fact, their victory appeared to have ripple effects in other communities. But like so many other aspects of life in the midst of a pandemic, things changed in a hurry.

The U.S. Environmental Protection Agency (EPA) classified ethylene oxide, or EtO, as a human carcinogen in December 2016. According to the agency, exposure via inhalation increases the likelihood of developing certain cancers and other respiratory and neurological ailments. EPA has not established a reference dose, or maximum acceptable dose, for EtO, but the U.S. Agency for Toxic Substances and Disease Registry’s (ATSDR) Cancer Risk Evaluation Guide (CREG) estimates concentrations of a carcinogen at which there is an elevated risk of one additional cancer case in one million people exposed over a lifetime. ATSDR’s CREG for ethylene oxide is 0.00021 µg/m3.

Despite being classified as harmful, EtO is used to sterilize nearly half of all medical devices that require sterilization in the United States. EPA’s 2016 Toxics Release Inventory identified more …