Each year,
8 million premature deaths are caused by indoor and outdoor air pollution.
Ninety one percent of the global population live in places where pollution exceeds the guidelines defined by the World Health Organisation (WHO). Outdoor air pollution affects populations in industrialised and developing countries, but
disproportionately affects low- and middle-income countries. There is a high level of consensus that the issue of ambient (outdoor) air pollution needs to be addressed, but relatively less attention has been given to indoor air pollution.
It is estimated that nearly half of deaths caused by poor air quality (
3.8 million) are due to indoor air pollution.
Common illnesses attributed to indoor air pollution include pneumonia, stroke, ischemic heart disease, chronic obstructive pulmonary disease, and cancer.
Indoor air quality remains largely unregulated.
People spend, on average,
65 percent of their time inside their homes. A growing body of research suggests that indoor air pollution can be much more concentrated than pollution outside.
The Environmental Protection Agency found that indoor air pollution in US homes can be 2 to 5 times higher than outdoor pollution. A recent study found that cooking a thanksgiving dinner caused indoor air quality to degrade substantially with particulate matter (PM) reaching
285 micrograms per cubic meter. For comparison, the average outdoor air quality in Delhi during the worst months of pollution is
225 micrograms.
Many common household items emit gaseous or particulate pollution. Even if these emissions remain at low levels, most indoor spaces have multiple emitting sources, the
cumulative effects of which can quickly lead to poor indoor air quality. The links between common household pollutants that affect air quality and our health are well established and can have
short and long-term effects. Yet, indoor air quality remains largely unregulated.
Outdoor air pollution easily enters indoor spaces too; these are typically pollutants from things like industrial activities and traffic.
There are
three broad categories of indoor air pollution sources, including 1) outdoor air quality and pollutants, 2) human activities inside buildings, and 3) building and construction materials, equipment, and furnishings. Outdoor air pollution easily enters indoor spaces too; these are typically pollutants from things like industrial activities and traffic. Radon is another challenge; it is a naturally occurring radioactive gas that can
enter homes through the ground or cracks in a building’s foundation, and can be released from decaying building materials. In the US, radon exposure is the
leading cause of lung cancer among non-smokers.
Particulate matter from indoor and outdoor sources is linked to a wide range of
health effects including nonfatal heart attacks, irregular heartbeat, increased symptoms of asthma, impacts on lung function and respiratory symptoms, and premature death among individuals with heart or lung disease.
Many of the furniture, home furnishings, and electronics that we put in our homes also have toxic chemicals that can be released in the form of volatile organic compounds (VOCs).
Human activities including smoking indoors, cooking, burning candles, using a fireplace, having pets, and cleaning with toxin-emitting products — all impact indoor air quality. Globally,
3 billion people cook with solid fuels (wood, dung, or crop waste).
Even improved cooking stoves that use natural gas or propane can release carbon monoxide, formaldehyde, sulfur dioxide, and nitrogen dioxide —
known to lead to increasing asthmatic symptoms and respiratory damage.
Building materials often include toxic chemicals that erode in the form of dust, or off-gas. Commonly known pollutants also include lead and asbestos. Importantly, many of the furniture, home furnishings, and electronics that we put in our homes also have toxic chemicals that can be released in the form of volatile organic compounds (VOCs). VOCs are gaseous chemicals, which in high levels are
known to increase cancer risk; cause eye, nose and throat irritation; headaches; loss of coordination; as well as causes nausea and damage to the liver, kidneys, and central nervous system.
Homes can also have high levels of biological allergens and microorganisms like insects, mites, mold, and bacteria.
VOCs are released from a
wide range of household materials and products including mattresses, cleaning products, dry cleaning, carpeiting, and cosmetics. In a study of 47 homes in the UK,
45 percent of homes were found to have VOC levels that exceed guidelines. One of the most common household VOCs is caused by formaldehyde.
Common household items with formaldehyde — which is known to cause cancer —
include things like composite wood products such as plywood and particleboard, glues and finishes used in furniture, fabrics, wallpaper and paint.
Homes can also have high levels of biological allergens and microorganisms like insects, mites, mold, and bacteria. These have been
linked to asthma and allergies, respiratory infections, fever, digestive problems, and chronic respiratory illness.
Information and awareness campaigns are necessary for informing the public about existing indoor air pollution sources and risks.
Indoor air pollution is not just a challenge for homes but other indoor environments such as schools, public buildings, and offices too. The effects of indoor air pollution are also not equally distributed, with some populations including children, the elderly, low-income individuals, minority groups and indigenous people being
disproportionately impacted. We know that indoor air quality is a pervasive problem, and we know to a large extent the causes of poor indoor air quality. We also know that indoor air pollution is linked to a wide range of health issues.
To improve indoor air quality and improve health we need stricter standards for products and buildings. We also need integrated action plans and policy frameworks for addressing indoor air quality in homes, public buildings, and offices. Third, information and awareness campaigns are necessary for informing the public about existing indoor air pollution sources and risks. And finally, we need to continue efforts towards addressing ambient air pollution. As countries work towards addressing outdoor air pollution, we also have to look inside of buildings to address the many sources and high levels of pollution found within them.
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