Hydroxyl generator

What it means

Hydroxyl generators are machines restorers rent or bring to jobs for smoke, sewage and other odors. They use ultraviolet lamps to produce hydroxyl radicals, highly reactive molecules that oxidize odor-causing compounds in the air and on surfaces.

EPA’s technical summary of residential air cleaners describes the same chemistry in related devices. In photocatalytic oxidation, ultraviolet light on a catalyst forms hydroxyl radicals that oxidize pollutants. EPA adds that these devices are often ineffective at completely transforming gaseous pollutants indoors and can generate harmful byproducts such as formaldehyde, acetaldehyde, nitrogen dioxide and carbon monoxide.

Why it matters to your home and your bill

Hydroxyl generators are often sold as a gentler alternative to ozone that can run with people present. We found no EPA guidance confirming that claim, and EPA notes that research has not shown such technologies remove gases effectively in portable residential air cleaners. Ask the company which machine it will use, how many days it will run, whether you should be home, and how that matches the manufacturer’s instructions. Make sure the odor source is cleaned first. Equipment days are billed, so the number should be justified. See our page on smoke odor removal.