Lecture 4 Indoor Air Pollutants

Indoor Air Pollution Overview

  • Indoor air pollution linked to 2.8 million deaths in 2019 and 3.2 million in 2020.

  • Pollutants may be concentrated indoors due to impermeable walls.

Sources of Indoor Air Pollutants

Natural Sources

  • Radon

    • Gas from the decay of uranium in rock.

    • Invisible, odorless gas that seeps in through foundation cracks or groundwater.

  • Mold

    • Fungus that releases spores. Found in poorly ventilated areas.

    • Can cause respiratory issues and allergy-like symptoms.

  • Dust

    • Consists of skin cells, hair, pet dander, bacteria, pollutants.

    • Small particles (<2.5μm) are most harmful.

Anthropogenic Sources

  • Combustion

    • Major source of indoor air pollution; includes biomass and fossil fuels.

    • Produces harmful gases like CO, CO2, NOx, SO2.

  • Asbestos

    • Material used in insulation; causes mesothelioma when inhaled.

    • Illegal in schools and public buildings.

  • VOCs (Volatile Organic Compounds)

    • Found in household products; some can be harmful (e.g. formaldehyde).

  • Lead (Pb)

    • No safe exposure level; can result in severe health effects, especially for children.

    • Sources include old paint and lead pipes.

Health Effects

Radon

  • Radiation from radon damages lung cellular DNA, leading to lung cancer.

  • Second leading cause of lung cancer in the U.S. after cigarettes.

Carbon Monoxide (CO)

  • Colorless, odorless gas that can cause severe poisoning.

  • Binds to hemoglobin, impairing oxygen transport.

  • Can result from malfunctioning heaters or cooking appliances.

Strategies to Reduce Risk

  • Radon Testing

    • Use testing kits and fix foundation cracks.

  • Mold Control

    • Address humidity and ventilation issues.

  • VOCs and Lead Management

    • Use safer alternatives and ensure proper removal of hazardous materials.

Sick Building Syndrome

  • Occupants experience health symptoms linked to building conditions with no identifiable cause.

  • Symptoms may arise from poor ventilation and chemical contaminants.