ventilation system

How to use CO2 monitors to check for poor ventilation

As we move beyond the main peaks of the Coronavirus pandemic, it remains important to conduct COVID-19 risk assessments in workplaces, and a key element in that is to check for poor ventilation.

Guidance from the HSE for the post-pandemic period states: “The priority for your risk assessment is to identify areas of your workplace that are usually occupied and poorly ventilated.

“You should prioritise these areas for improvement to reduce the risk of aerosol transmission.”

One suggested way to achieve this is through the use of CO2 monitors to check for poor ventilation by detecting higher accumulations of exhaled breath.

How to check ventilation with a CO2 monitor

Humans inhale oxygen and exhale carbon dioxide. In well ventilated areas, the excess carbon dioxide will disperse.

Elevated levels of CO2 in an occupied area are an indication that the carbon dioxide is not dispersing, which in turn suggests poor ventilation.

While this is not directly linked with the spread of infectious diseases like COVID-19, it is a sign that the risk may be greater and action should be taken to ventilate the area.

Where to use a CO2 monitor to test ventilation

For an accurate measurement of the ventilation in a space, make sure you use your CO2 monitor away from obvious sources of ventilation, such as doors and windows, or air conditioning vents.

Also ensure the detector is more than 50cm away from any people present, as their immediately exhaled CO2 can lead to a higher reading.

CO2 monitors are best placed at head height, although portable CO2 detectors offer versatility to measure at different heights and locations as appropriate.

Best practice for CO2 detection

Always use a calibrated CO2 detector for the most accurate results. If possible, repeat the reading several times over the course of the day, accounting for variations in how the space is used and when it is at peak occupancy.

By taking an average of your results, you can get a more comparable reading, so that you can identify the locations around your premises where action is most needed to improve ventilation.

Make sure you record your results in full, not only including the quantity of CO2 detected, but also relevant details like the date and time of the reading, and any notes about occupancy and ventilation at the time.

What are safe CO2 levels indoors?

The HSE recommends taking action to improve ventilation if you detect CO2 at concentrations of more than 1,500 parts per million.

However, for an indoor space to be considered well ventilated, readings should be consistently below 800 ppm.

The HSE guidance suggests aiming for 800 ppm as a maximum CO2 level indoors in places where there is frequent talking or singing, or physical activity such as sports and dancing.

By improving ventilation, you can not only keep CO2 levels down, but also help to disperse any Coronavirus cells present in the space.

As we move beyond the pandemic, this will allow you to meet the ‘fresh air’ element of government guidance, and protect employees and any members of the public who come into your premises.

For more information about CO2 monitors or ventilation in the workplace, contact Envin Scientific to talk to one of our specialists.