Using CO2 monitors

There is new advice on using CO2 monitors. Although CO2 levels are not a direct measure of possible exposure to Covid, a build-up of CO2 in an area can indicate the need for improved ventilation. Again, the guidance points to HSE advice on using a CO2 monitor (see below).

“CO2 measurements should be used as a broad guide to ventilation within a space rather than treating them as safe thresholds,” says the new guidance.

A consistent CO2 value of less than 800 parts per million (ppm) is likely to indicate that a space is well ventilated, while a CO2 concentration of above 1500ppm in a space indicates poor ventilation. Employers need to take action to improve ventilation where CO2 readings are consistently higher than 1500ppm.

Where there is continuous talking or singing, or high levels of physical activity, such as dancing, playing sport or exercising, it recommends keeping CO2 levels below 800ppm.

In large areas, multiple sensors may be required to provide meaningful information.

Monitors are less likely to be useful in areas occupied by people for short periods or varying amounts of time; areas where air cleaning units are in use — filtration can remove contaminants like Covid-19 from the air but not remove CO2; small spaces like changing rooms, toilets or small meeting rooms; spaces used by few people; and areas where CO2 is produced as part of a work process.