Currently there is much interest in using UV and ozone generators to kill the SARS-CoV-2 virus that causes COVID-19 disease. Hospitals and businesses are treating entire patient rooms, offices, and other workspaces during off hours while no one is permitted to enter the rooms. During ozone treatment, concentrations over 20 ppm are recommended by generator manufacturers for adequate disinfection. UV light kills viruses directly, but may generate some ozone as a by-product. Workers using batch equipment sterilizers, where several thousand ppm of ozone may be applied, also need protection. Ozone is highly toxic to humans, and therefore UNI ozone monitors are being employed to ensure that residual ozone has decomposed or ventilated before employees can re-enter the workspace safely. Ozone has an 8-hour TWA exposure limit of about 0.07 ppm in many countries including most of Europe. In the US, the ACGIH makes the following 8-hour TWA recommendations:
The UNI Ozone monitor has a resolution of 0.01 ppm and can measure up to 5 ppm ozone with a response time of 60 seconds, making this small, low-cost unit convenient and accurate for protection of the workforce.
23 April 2020