Every person exhales about 18 litres of CO₂ per hour. In a meeting room or open-plan office where ventilation has not been sized for current occupancy, CO₂ climbs through the morning and peaks in the afternoon — exactly when headache complaints rise. UK Approved Document F targets a daily average below 1,000 ppm; above 1,500 ppm, headaches and reduced concentration are reliably reported. More on high CO₂ →
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Cause 1 — CO₂ from under-ventilation
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Cause 2 — VOCs from cleaning, furniture and print
Volatile organic compounds from cleaning chemicals, freshly installed furniture, MDF, carpets, printers and air fresheners irritate mucous membranes and trigger headaches. The pattern is often worst on Mondays (weekend cleaning), near print rooms, or in the weeks following a refurbishment. More on VOCs in buildings →
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Cause 3 — Heat and dry air
UK offices commonly run too warm (above 24 °C) in summer and too dry (below 30% RH) in winter. Both compound CO₂ and VOC effects on the head. A short thermal-comfort log alongside the IAQ test usually settles the question.
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The right test to commission
Deploy continuous monitoring for CO₂, TVOC, PM2.5, temperature and relative humidity across the affected rooms for 7–14 working days. Cross-reference the time-series with a simple staff symptom diary. The exceedances against UK Approved Document F and CIBSE TM40 thresholds tell you whether the issue is ventilation rate, a chemical source, or thermal comfort.
CO₂ monitoring service → · VOC testing service → · Full IAQ testing →
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Frequently asked questions
Can poor office air really cause headaches?
Yes. CO₂ above ~1,000 ppm causes measurable drops in concentration and is associated with headaches; VOCs from cleaning products, new furniture and printers irritate mucous membranes and trigger headaches; low humidity and high temperature compound the effect. The link is well established in HSE and CIBSE literature.
What CO₂ level causes headaches in an office?
Cognitive impairment becomes measurable above 1,000 ppm. Headaches, drowsiness and difficulty concentrating are commonly reported by 1,400–2,000 ppm. UK building regulations (Approved Document F) target a daily average below 1,000 ppm and a peak below 1,500 ppm for office spaces.
How quickly can a headache be linked to the office air?
If the headache eases within an hour or two of leaving the building and returns within an hour of re-entering — particularly in the afternoon and in densely occupied rooms — the office is the likely cause.
What test should we book first?
Continuous CO₂ + TVOC logging in the affected rooms for at least one working week, plus a brief occupant symptom diary. This costs a fraction of a full IAQ survey and identifies under-ventilation or a VOC source in the majority of UK office cases.