Indoor air quality (IAQ) can be affected by ventilation, occupancy, building activities and the condition of mechanical systems. Dust, particulate matter, microorganisms, and gases such as carbon dioxide (CO₂), carbon monoxide and volatile organic compounds (VOCs) can all affect the indoor environment.
What does the law say?
Good indoor air quality isn't simply a matter of comfort. The Workplace (Health, Safety and Welfare) Regulations 1992 require enclosed workplaces to be effectively and suitably ventilated.
The accompanying Approved Code of Practice (ACOP) L24 provides practical guidance on meeting these requirements. Employers also have duties under the Management of Health and Safety at Work Regulations 1999 to assess workplace risks and implement appropriate controls.
Where workplace activities create airborne contaminants, the Control of Substances Hazardous to Health (COSHH) Regulations 2002 may also apply. This includes exposure to substances such as dusts, fumes, vapours, gases and biological agents.
Is CO₂ enough?
CO₂ monitoring is increasingly common in workplaces and can provide a useful indication of ventilation performance. Elevated CO₂ levels can suggest that insufficient fresh air is being supplied to an occupied space.
However, CO₂ is not a complete measure of indoor air quality. Other pollutants can be present even when CO₂ levels are acceptable. For substances covered by COSHH, specific Workplace Exposure Limits may also apply.
How do you know if your workplace has good IAQ?
Understanding what is happening within the building is the first step.
An effective assessment can consider ventilation performance alongside airborne particles, dust, microbiological contaminants, gases, temperature and humidity. This provides a more complete picture than relying solely on CO₂ monitoring or waiting for occupants to report concerns.
With hybrid working and changing occupancy patterns, it is also worth considering whether existing ventilation systems remain suitable for how buildings are being used today.
Good IAQ should form part of a wider approach to indoor environmental quality. For facilities managers and employers, the question isn't simply “Do we have ventilation?” but “Is our ventilation performing effectively, and can we demonstrate it?”
A proactive assessment can help identify potential issues, support risk assessments and provide evidence-based recommendations for maintaining a healthy and comfortable workplace.