Rules of Thumb for Better Indoor Air Quality at Home

Indoor air quality (IAQ) plays a critical role in our health and comfort. From mold to chemical fumes, homes can contain pollutants that are invisible yet harmful. According to the World Health Organization, poor indoor air contributes to over 3.2 million deaths annually worldwide. While not everyone can afford air testing or filtration systems, research-backed rules of thumb can help maintain a healthy indoor environment with simple daily habits.

Understand the Hidden Pollutants

Indoor air can be more polluted than outdoor air—up to 2 to 5 times worse, according to the U.S. EPA. Common indoor pollutants include:

• PM2.5 / PM10 (Particulate Matter) – Emitted from cooking, candles, and dust. Can enter deep into the lungs and bloodstream.

• VOCs (Volatile Organic Compounds) – From paints, cleaning products, air fresheners, and furniture. Known to cause irritation, headaches, and even long-term neurological and cancer risks.

• Nitrogen Dioxide (NO₂) – Produced by unvented gas stoves and heaters. Increases asthma and reduces lung function.

• Carbon Dioxide (CO₂) – Not harmful in small amounts, but elevated levels (>1000 ppm) signal poor ventilation and can impair cognition.

• Mold & Biological Allergens – Thrive in high humidity; can trigger asthma and allergic reactions.

• Radon – A naturally occurring radioactive gas that seeps from soil into homes. It’s the second leading cause of lung cancer in the U.S. and cannot be detected without testing.

Rule #1: Ventilate Regularly

• Open windows for 15–30 minutes daily to reduce CO₂, VOCs, and PM2.5. Use cross-ventilation by opening windows on opposite walls.

• After cooking or cleaning, ventilate for 45–60 minutes to flush pollutants.

• Ceiling fans or portable fans should run for 10–15 minutes during and after ventilation to help circulate clean air.

• If outdoor air is poor (due to traffic or wildfires), limit opening windows and use mechanical ventilation with filtration.

Rule #2: Control Moisture and Prevent Mold

• Keep indoor humidity between 30–50%.

• After showering, run the bathroom exhaust fan for 20–30 minutes.

• Use dehumidifiers in damp areas like basements. Fix leaks and avoid drying laundry indoors without proper ventilation.

Rule #3: Be Smart About Sources

• Choose low-VOC paints, sealants, and furniture.

• Skip synthetic candles and aerosol sprays.

• Always use a range hood (vented outdoors) when cooking, especially with gas.

• Let new furniture or carpets air out for 48 hours in a ventilated room before regular use.

Rule #4: Filter Your Air

• Use a MERV 13 or higher HVAC filter and change it every 60–90 days.

• Run portable HEPA air purifiers for 8–12 hours/day in high-use rooms.

• For gas stoves or strong odors, use a purifier with an activated carbon filter.

Rule #5: Test for Radon

Unlike other pollutants, radon has no smell, taste, or visible sign.
The U.S. EPA and WHO recommend testing every 2–5 years, or after major renovations or changes to ventilation.
The best time to test is during colder months (November–March), when homes are sealed and radon levels peak. Long-term tests (90+ days) offer more reliable results. If levels exceed 4.0 pCi/L, mitigation is strongly recommended.

Rule #6: Clean with Purpose

• Vacuum with a HEPA filter at least twice per week.

• Damp-wipe surfaces weekly to avoid stirring up dust.

• Wash bedding weekly in hot water to remove allergens.

• Adopt a no-shoes policy to reduce dirt, pesticides, and outdoor particles inside.

Final Word

You don’t need expensive sensors to breathe cleaner air. By following these scientifically supported rules—ventilating regularly, controlling moisture, reducing chemical exposure, filtering air, and testing for radon—you can significantly reduce health risks and improve your indoor environment. It’s air care by habit—rooted in science, accessible to everyone.

References

• U.S. Environmental Protection Agency – Indoor Air Quality & Radon

• World Health Organization – Household Air Pollution Factsheet

• Harvard T.H. Chan School of Public Health – Healthy Buildings Program

• Centers for Disease Control and Prevention (CDC) – Indoor Environmental Quality Guidelines

• American Lung Association – Radon and Indoor Air

• ASHRAE – Residential Ventilation and Humidity Standards

• California Air Resources Board – Indoor Pollutant Studies