In March 2020, the FDA relaxed its regulations on hand sanitizer to meet unprecedented demand in the face of a new pandemic. Companies everywhere began making and selling the stuff—and creating at least one airborne toxic event in the process. In Wired, Amy Martyn details the environmental nightmare visited upon unsuspecting residents of Carson, California.

By the second week of the odor, a resident noticed that the mailboxes in her condo had turned black overnight, a sign of a chemical reaction between aluminum and hydrogen sulfide. Others spotted workers spraying something from hoses into the channel. LA County Public Works began applying a deodorizer called Epoleon and said the smell would clear within five days.

On October 14, the Department of Public Health sent a notice to local doctors that people were reporting dizziness, vomiting, and shortness of breath. It still described the hydrogen sulfide levels as “elevated, but not toxic” and maintained that “the source appears to be naturally decaying organic material.”