“According to the U.S. Department of Labor’s Occupational Safety and Health Administration (OSHA), every year, workers die from CO poisoning, usually while using fuel-burning equipment and tools in buildings…
Portable CO detectors are a great choice when workers are in a place where CO is a possibility, but there aren’t any CO detectors available at the site.”

Preventing Carbon Monoxide Poisoning in Your Facility | Cleaning & Maintenance Management (cmmonline.com)