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Indoor Air PollutionEdit

Indoor air pollution refers to the suite of contaminants that accumulate inside homes, workplaces, and other enclosed spaces, potentially harming the health and comfort of occupants. Because people spend a large portion of their lives indoors, and because indoor environments can trap gases, particles, and biological agents, indoor air quality has become a central concern for public health, housing policy, and building design. In practical terms, the quality of the air inside a building reflects a combination of pollutant sources, the building’s ventilation and filtration, and the behavior of the people inside it. When managed well, indoor environments can protect health and productivity; when neglected, they can contribute to a range of acute and chronic health issues.

While outdoor air pollution often dominates headlines, indoor air pollution is a distinct and sometimes more persistent risk. Pollutants derive from combustion (for heating, cooking, and smoking), building materials and furnishings, consumer products, and outdoor air that leaks into the space. The interplay among emission sources, ventilation, filtration, humidity, and temperature determines the actual exposure of occupants. Because regulations and standards for indoor spaces are less uniform than those for outdoors, practitioners rely on a mix of engineering controls, building codes, and voluntary guidelines to reduce risk. Indoor air quality is the broader field that encompasses these concerns, and it intersects with Public health and Building science.

Causes and sources

  • Common pollutants and their origins:
    • Particulate matter from combustion, cooking, candles, and incense. These fine and ultrafine particles can penetrate deep into the lungs. Particulate matter
    • Gases produced by combustion and chemical reactions, such as carbon monoxide and nitrogen dioxide. Carbon monoxide Nitrogen dioxide
    • Volatile organic compounds emitted by paints, finishes, cleaning products, office equipment, and many consumer goods. Volatile organic compounds
    • Radon, a radioactive gas that can seep into buildings from the surrounding soil and rock. Radon
    • Biological contaminants, including mold, dust mites, bacteria, and viruses, which thrive in damp or humid environments. Mold
    • Formaldehyde and other aldehydes released by some building materials and consumer products. Formaldehyde
  • Outdoor air influence and building characteristics:
    • Outdoor pollutants can infiltrate indoors through cracks, ventilation systems, and even everyday openings. Outdoor air {{Indoor air quality}}
    • Ventilation rates, filtration efficiency, and humidity control strongly affect indoor concentrations. Ventilation Filtration
    • Energy-efficient designs that tightly seal buildings can reduce ventilation unless balanced with proper air exchange. Building science

Health effects and exposure

  • Short-term effects can include eye, nose, and throat irritation, headaches, dizziness, and fatigue. High concentrations of some pollutants can cause acute symptoms and worsen asthma. Asthma
  • Long-term exposure to pollutants like fine particulate matter and certain VOCs is associated with cardiovascular and respiratory diseases, and may contribute to cancer risk for some substances. Cardiovascular disease Respiratory disease
  • Sensitive populations, such as children, the elderly, or those with preexisting conditions, may experience greater health impacts from indoor air pollutants. Pediatric health
  • Measurement in practice often uses indicators such as CO2 as a proxy for ventilation adequacy, alongside direct measurements of pollutants like PM2.5, VOCs, radon, and CO. CO2 PM2.5

Measurement, standards, and regulation

  • There is no single universal indoor air quality standard; instead, policymakers rely on a combination of national guidelines, professional standards, and local building codes. Notable references include guidance from World Health Organization, and standards from engineering bodies such as ASHRAE. World Health Organization ASHRAE
  • In the United States, the Environmental Protection Agency emphasizes reducing exposure to known outdoor pollutants and supporting ventilation and filtration practices in homes and schools, while recognizing the role of indoor sources. Environmental Protection Agency Ventilation
  • Building design and operation play a central role, including selection of low-emission materials, effective ventilation, and appropriate filtration. Standards like ASHRAE 62.1 outline recommended ventilation and air quality practices for commercial buildings. ASHRAE
  • Testing and remediation for specific hazards, such as radon in homes or mold growth, are common components of environmental health efforts. Radon Mold

Prevention, mitigation, and best practices

  • Source control: Reducing emissions at the source by selecting low-emission products, using noncombustion cooking methods when possible, and avoiding smoking indoors. Volatile organic compounds Tobacco smoke
  • Ventilation and dilution: Providing adequate fresh air exchange to dilute indoor pollutants, while balancing energy efficiency. This includes mechanical systems and natural ventilation where feasible. Ventilation
  • Filtration and air cleaning: Using high-efficiency filtration (such as HEPA filters) and scrubbers to remove particles and some gases from indoor air. Filtration
  • Humidity and moisture control: Keeping indoor humidity in a range that discourages mold growth and dust mite proliferation. Humidity
  • Building design and maintenance: Selecting durable, low-emission materials; ensuring proper sealing and insulation; and maintaining heating, ventilation, and air-conditioning systems. Building science

Global perspectives and policy debates

  • In many high-income countries, indoor air quality is addressed through a mix of building codes, workplace safety rules, and consumer product regulations. In low- and middle-income settings, indoor air risks are often driven by reliance on solid fuels for cooking and heating and by building materials with higher emission profiles. Public health
  • The policy conversation tends to center on the proper balance between public health protections and costs to households and businesses. Proponents of stronger standards argue that preventing disease and improving productivity justify investment in ventilation, filtration, and safer materials. Critics often frame some rules as imposing costs or reducing consumer choice, emphasizing market-based solutions and targeted interventions for high-risk settings. In any case, robust risk communication, transparent cost–benefit analyses, and flexible implementation are common themes.
  • There is ongoing discussion about how to prioritize pollutants and settings. Radon, tobacco smoke exposure, and certain high-emission VOC sources are frequently identified as priority issues due to well-established health risks. Radon Tobacco smoke Volatile organic compounds

See also