Indoor Air QualityIAQ

Indoor Air Quality — IAQ — is the measure of the air inside the building the occupant breathes, and the concern the industrial hygienist investigates when the workforce reports the headache, the fatigue, and the respiratory complaint that cluster into the sick-building report. The contaminants are the carbon dioxide that flags the ventilation adequacy — the ASHRAE 62.1 target sits below 1,000 ppm, and a reading above it says the outside-air rate is not keeping up with the occupancy — the volatile organic compounds off-gassed from the finishes and the furnishings, the particulates, the biological contaminants of the mould and the Legionella and the allergens, and the radon in the geology under the building. Each one has its source, its pathway, and its control.

The regulatory gap is that OSHA has no comprehensive IAQ standard, and the agency enforces the indoor air under the General Duty Clause, the Section 5(a)(1) catch-all that requires the employer to keep the workplace free of the recognised hazard — a weak lever that puts the burden on the employer to recognise the IAQ risk the standard does not define. The NIOSH IAQ investigation is the response to the sick-building complaint, and the investigation that finds the source — the under-ventilated floor, the mould in the air handler, the VOC from the renovation — is the one that closes the complaint. The IAQ programme that monitors the CO2, the VOC, and the humidity proactively is the one that catches the drift before the report. See Legionella, hazard, and TLV.