Indoor Air Pollution

Indoor Air Pollution and Lung Health

What Is Indoor Air Pollution?

Indoor air pollution refers to the presence of harmful pollutants inside homes, schools, transportation hubs, and offices. Surprisingly, indoor air pollutants can be 2–5 times more concentrated than those outdoors, exposing individuals to continuous health risks. Over 900 different chemical compounds have been detected in indoor environments.

While workplace-related exposure is typically categorized as occupational lung hazards, everyday indoor exposure in domestic settings remains a major public health concern—especially for lung health.

Common Sources of Indoor Air Pollution

1. Human Activities

• Tobacco smoke

• Use of biomass fuels (wood, charcoal, animal dung) for cooking and heating

• Cleaning agents, air fresheners, cosmetics, and pesticides

2. Building Materials & Construction

• Poor ventilation

• Low-quality or aging construction materials

• Use of volatile organic compounds (VOCs) in items like paint and vinyl floors

3. Biological Allergens

• Pets, plants, and dust mites

• Dampness and mould

• Poor hygiene or pest infestation (e.g., rodents)

Harmful Effects on Lung Health

Particulate Matter (PM)

Particulate matter, especially PM2.5 and PM10, can penetrate deep into the lungs. Tobacco smoke is a major source indoors, accounting for up to 90% of PM exposure. For children with asthma, every 10 μg/m³ increase in PM2.5 raises the likelihood of night-time wheezing symptoms by 6–7%.

Biomass Fuels and Lung Disease

Around half of the global population uses biomass fuels for cooking or heating, primarily in developing countries. This generates high levels of carbon monoxide (CO) and PM.

• 3.5× increased risk of lung infections in children

• 2.8× increased risk of COPD

• 2.3× increased risk of chronic bronchitis in adults

Nitrogen Dioxide (NO₂)

Generated by gas-fueled appliances, NO₂ contributes to respiratory symptoms such as wheezing, chest tightness, and shortness of breath.

Volatile Organic Compounds (VOCs)

VOCs come from cleaning agents, pressed wood furniture, synthetic flooring, and personal care products.

• 11× risk of chronic bronchitis with formaldehyde exposure

• 17% increase in childhood asthma for every 10 mg/m³ rise in formaldehyde

• 3.4× increased risk of persistent wheeze with plastic exposure

• General asthma risk increases by 1.2–2.9× due to VOCs

Radon Exposure

Radon, a radioactive gas found in soil and concrete, is the second-leading cause of lung cancer after smoking. Annually:

• 2,100–2,900 U.S. lung cancer deaths in non-smokers are linked to radon

• 1,100 deaths in the UK are attributed to radon exposure

Indoor Allergens

Allergens such as pet dander, dust, and pollen can both trigger and exacerbate asthma and other lung diseases. Some early-life exposure may be protective, but high or continuous exposure tends to increase risk.

Dampness and Mould

Damp indoor conditions lead to mould growth on walls, ceilings, and furniture, which affects 10–50% of homes.

• 30–50% increased risk of asthma

• Associated with bronchitis, lung infections, and shortness of breath

Protecting Lung Health Indoors

Improving indoor air quality is essential for preventing lung diseases such as asthma, COPD, bronchitis, and even lung cancer. Solutions include:

• Using exhaust fans in kitchens and bathrooms

• Avoiding indoor smoking

• Using air purifiers

• Regular maintenance of heating systems

• Improving home ventilation

• Minimizing use of VOC-containing products