What can indoor air quality testing actually measure?

Start with the concern, then choose the measurement

Tell the assessor what you have noticed, which rooms are involved and when it happens. The EPA describes a range of possible indoor pollution sources, including combustion, household products and building materials. That is one reason a single reading cannot describe the whole indoor environment.

Source: EPA: a guide to indoor air quality.

Carbon dioxide: a ventilation clue

CO₂ measurements can help assess ventilation in occupied spaces. HSE’s workplace guidance explains how occupancy, monitor position and measurements over time affect interpretation. A CO₂ reading is not a mould test, and it is not a carbon monoxide alarm. Its workplace guidance should not be treated as a universal pass/fail certificate for a home.

Source: HSE: using CO₂ monitors in workplaces.

Ask what the other measurements mean

You may be offered humidity readings, particle measurements or mould sampling. Ask for the exact parameter and method rather than relying on a device’s overall “good” or “poor” score. For mould sampling in particular, agree what is collected and how the result will be interpreted.

Ask whether the equipment identifies a particular substance or gives a broader indication. Also ask how a brief visit differs from monitoring over a longer period. These are useful questions even if you have never used a meter before.

A brief to send with your enquiry

• The room and the issue you want investigated.
• When it occurs and whether it is intermittent.
• Any recent decorating, building work or known water damage.
• Whether you need an initial assessment or a specific report for someone else.
• Your postcode, access arrangements and preferred appointment times.

Ask for interpretation, not just numbers

Request units, sample locations, dates and the conditions recorded during the visit. Ask what comparison is being used and whether it is appropriate to your type of property. A report should help you decide what to do next and explain what remains uncertain.

EMS can discuss an air-quality enquiry with you and confirm the available scope before booking. Do not assume radon, asbestos, carbon monoxide or every chemical is included: ask for the exact list. If you have a specific concern outside that scope, it may need a different specialist.