Hecena — Indoor Air Quality at Home | hecena.com
A table of pollutant types with their measured levels and units: CO limits of 10–100 mg/m³ by exposure time, winter ACH of 0.50–1.47, and the 90% share of time spent indoors.
Indoor air carries a long list of pollutants: secondhand tobacco smoke, combustion products, radon, molds and other allergens, carbon monoxide, volatile organic compounds, legionella, asbestos fibers, carbon dioxide, ozone and particulates. They differ in how they enter the air, how long they stay, and which of the three remediation levers — source control, filtration, ventilation — actually works on them.
Carbon monoxide is the pollutant with the sharpest published limits. The WHO recommends that acute exposure not exceed 10 mg/m³ over 8 hours, 35 mg/m³ over one hour, and 100 mg/m³ over 15 minutes. Each figure is tied to its averaging window; a peak of 60 mg/m³ lasting two minutes is a different event from 60 mg/m³ sustained for an hour.
Ventilation rates are the other side of the equation. In winter, air changes per hour may range from about 0.50 in a tightly air-sealed house to about 1.47 in a loosely air-sealed house. At the low end, pollutants accumulate between air exchanges; at the high end, you pay for freshness in heating energy.
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The 90% figure explains why all of this matters. Americans and Europeans spend on average approximately 90% of their time indoors, so indoor concentrations — not outdoor readings — dominate total exposure for most of the pollutant list above.
The WHO estimates that 3.2 million people die prematurely every year from illnesses attributed to indoor air pollution. That figure reflects chronic exposure over years, which is why a one-time reading below any acute limit does not settle the question of whether your home's air is healthy.
For each pollutant on the list, ask which lever applies. Combustion products respond to ventilation within minutes; radon and asbestos require source control because dilution alone never removes them; mold follows moisture, so fix the water source first.
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