Air Quality

How gas and propane stoves raise nitrogen dioxide and carbon monoxide indoors, what the WHO, Health Canada, and the US EPA set as limits, what the evidence on childhood asthma shows and where it's debated, and how to cut your exposure.

What the EPA's AQI from 0 to 500 means, its six colour-coded categories, why the reported number is the worst pollutant's, and how NowCast keeps it current during smoke and smog.

Why radon is a leading cause of lung cancer after smoking, the EPA's 4 pCi/L action level and the WHO's 100 Bq/m³ reference level, how to test, and why long-term averages matter more than one reading.

What volatile organic compounds are and where they come from indoors, why a monitor's total VOC number has no health limit and is hard to compare, and why formaldehyde, the one VOC with clear guidelines, is the one worth measuring.

What fine particles are and why they harm health, the WHO's 5 µg/m³ annual and 15 µg/m³ daily guidelines, the EPA's 9.0 µg/m³ standard, and what indoor monitors can and can't tell you.

Why the US EPA suggests keeping indoor humidity between 30 and 50 percent and under 60, what too damp and too dry air do, how temperature changes the reading, and how to follow your home's humidity.

What the guidelines actually say about carbon dioxide indoors, why 1,000 ppm comes up so often, and how to measure and follow the air in your own home.