Indoor Air Pollutants and Asthma
Written by Mike S. Avelar, CPI
Indoor air pollutants can significantly affect asthma symptoms, especially in homes where ventilation is limited or moisture problems exist. Many common contaminants are invisible, odourless, and easy to overlook, but they can irritate the respiratory system and trigger asthma flare‑ups. Understanding how these pollutants behave helps homeowners reduce exposure and improve indoor air quality.
Common Indoor Air Pollutants Linked to Asthma
Health Canada identifies several indoor air contaminants that can affect respiratory health, especially for people with asthma.
Mould and Fungal Spores
Moisture problems allow mould to grow on building materials, releasing spores that can irritate the airways. Mould is a well‑known asthma trigger and can worsen symptoms for sensitive individuals.
Volatile Organic Compounds (VOCs)
Paints, cleaners, air fresheners, adhesives, and new furnishings can release VOCs. These chemicals evaporate at room temperature and may irritate the lungs, especially in poorly ventilated spaces.
Particulate Matter (PM2.5)
Fine particles from cooking, smoking, candles, fireplaces, and dust can enter the lungs and worsen asthma symptoms.
Nitrogen Dioxide (NO₂)
Gas stoves, heaters, and poorly vented combustion appliances can release NO₂, which can irritate the respiratory system.
Ozone and Other Chemical Irritants
Some air purifiers generate ozone, which can worsen asthma. Strong odours from cleaners, perfumes, and chemicals can also trigger symptoms.
How Indoor Pollutants Affect Asthma
Asthma involves inflammation and narrowing of the airways, making breathing more difficult. Exposure to allergens or irritants — including mould, dust mites, VOCs, smoke, and chemical fumes — can trigger or worsen symptoms.
Common reactions include:
- Wheezing
- Chest tightness
- Coughing
- Shortness of breath
- Increased sensitivity to airborne irritants
People with asthma may experience flare‑ups when indoor air quality is poor, especially during winter months when homes are sealed tightly and ventilation is reduced.
Improving Indoor Air Quality
Homeowners can take several steps to reduce indoor air pollutants and support better asthma control.
1. Reduce or Eliminate Pollutant Sources
Health Canada recommends removing or minimizing indoor contaminants whenever possible. This includes fixing moisture problems, choosing low‑VOC products, and maintaining combustion appliances.
2. Improve Ventilation
Ventilation helps dilute indoor pollutants. Use exhaust fans in kitchens and bathrooms, ensure HVAC systems are functioning properly, and open windows when weather allows.
3. Filter Indoor Air
High‑quality HVAC filters and HEPA air purifiers can reduce particulate matter and allergens. Avoid ozone‑producing devices.
4. Control Moisture
Moisture control reduces mould growth. Maintain indoor humidity between 30% and 50%, repair leaks promptly, and use dehumidifiers in damp areas.
5. Maintain Clean Indoor Spaces
Regular dusting, vacuuming with a HEPA filter, and cleaning soft furnishings help reduce allergens and airborne particles.
When to Seek Professional Help
Consider professional evaluation if:
- You suspect hidden mould
- Indoor air quality issues persist despite improvements
- Asthma symptoms worsen at home
- You have combustion appliances that may be releasing pollutants
Indoor air quality professionals can test for contaminants, assess ventilation, and recommend corrective measures.
Key Takeaways
- Indoor air pollutants and asthma are closely linked, especially in homes with poor ventilation or moisture issues.
- Common pollutants include mould, VOCs, particulate matter, and combustion by‑products.
- Improving ventilation, filtration, and moisture control can significantly reduce asthma triggers.
- Professional assessment may be needed for persistent or severe indoor air quality concerns.