Air pollution. It’s a term that brings to mind beaten-up cars belching out black exhaust fumes and factory chimneys releasing plumes of noxious smoke into the atmosphere.
Outdoor air pollution, predominantly caused by the burning of fossil fuels, dominates headlines and government policy. And yet increasingly, when it comes to health, it’s indoor air pollution – and the quality of the air inside our homes, workplaces and schools – that’s the key concern.
Studies conducted by the US Environmental Protection Agency (1) claim that indoor air can, in fact, contain higher concentrations of toxins than outdoor air – even in the most smog-ridden urban areas. For many people; especially the most vulnerable members of society such as children, the elderly and the sick, who tend to spend more time inside, this means that the health risks associated with poor air quality could, surprisingly, be more severe indoors than out.
The exponential growth in the number of health complaints and chronic diseases that are exacerbated or caused by indoor air pollution, from asthma to allergies and even mental health conditions, has led to the creation of a new umbrella label of ‘Building Related Illnesses’. Similarly, ‘Sick Building Syndrome’ (2) is now a recognised condition, comprising of various symptoms that appear to be directly linked to time spent in a building. Poor communities are often hit the hardest due to badly designed and ventilated housing and densely populated, pollution-heavy settings.
The issue is further compounded by the amount of time we now spend indoors: a staggering 87%, according to research. (3) Sociologist W.R. Ott sums the situation up succinctly, (4) when he states that “we are basically an indoor species”.
Given that we now spend so much time inside, the quality of the air we breathe within our indoor environments is of paramount importance. Understanding what the various indoor pollutants are, and how we might be affected by them, is the first step in finding ways to reduce air contamination and increase air purity.
The 5 main sources of indoor air pollution to be aware of, and the problems they can cause:
1. Toxic fumes released by everyday household products.
It might seem hard to believe, but the chemicals released (5) from the objects and products found in our homes, offices and schools can rival traffic exhaust as a source of air contamination. Known as ‘volatile organic compounds’, or VOCs for short, these invisible gases are emitted by a huge array (numbering in the thousands) of everyday indoor items, including:
new furniture or carpets
cleaning products and disinfectants
paints, paint strippers, varnishes and other solvents
aerosol sprays and air fresheners
pesticides like flea treatments or moth repellants
stored fuels and car care products
Concentrations of VOCs are thought (6) to be up to ten times higher indoors than outdoors, with certain activities – such as paint stripping – found to emit levels 1,000 times greater than “background outdoor levels”.
As with all pollutants, health impacts will of course vary depending on how often and for how long a person is exposed to these toxic gases, but reported symptoms range from headaches and dizziness to allergic skin reactions and even damage to the central nervous system. Even so, there have been relatively few studies into the severity of the risk posed, or any real protective standards set.
According to the United States Environmental Protection Agency, “no federally enforceable standards have been set for VOCs in non-industrial settings”, and “not much is known about what health effects occur from the levels of organics usually found in homes” – with the onus falling on the consumer to take care in their handling and disposing of toxic substances.
2. Allergens such as dust mites, pet dander and pollen.
Allergies are on the up across the world, with allergy now (7) the most common chronic disease in Europe – leading to growing concerns that we are in the midst of an allergy epidemic. Asthma diagnosis rates have also been increasing. A 2017 estimate (8) put the total number of asthma sufferers at 300 million, with this figure set to rise to 400 million over the next 5 years.
Allergens (9) like pollen, dust mites and pet dander can easily build up in indoor environments, making life extremely uncomfortable for allergic individuals and causing hard-to-ignore symptoms such as wheezing, sneezing, running eyes and difficulty breathing – sometimes triggering asthma attacks. Though too small to see, dust mites are found in mattresses, pillows and carpets, where they feed on human skin flakes. Both dust mite bodies and dust mite faeces are recognised allergens.
Our beloved pets also pose a problem, with animal hair and dander causing allergic reactions and compromising indoor air quality. Whilst mainly seasonal, once in your home, pollen particles can linger all year long; causing allergy sufferers prolonged discomfort. Pets can unwittingly traipse traces of pollen into living spaces, or airborne particles can be carried in via open windows or on our clothes.
3. Mould and fungus, caused by humid or damp conditions.
Often visible on bathroom tiles or damp walls with peeling paint, mould can grow (10) on almost any surface - especially where moisture or condensation has collected - and usually gives off a distinct, musty smell. The problem lies in the fact that some molds that grow in water-damaged buildings are toxic to humans, (11) and have been associated with an increased risk of disease. When scientists from Texas studied (12) patients who had been exposed to toxic mold in their homes, they found symptoms ranging from breathing difficulties to short-term memory loss and problems with balance and coordination.
Another paper (13) concluded that “toxic mold causes significant problems in exposed individuals”. Damp and condensation have even been linked to (14) emotional and behavioral problems in young children. Other experts have, however, questioned the accuracy of some such studies, saying “close examination of the literature reveals a confusing picture”, and that supportive evidence is not “well-substantiated”. On the whole though, it seems right to be aware of the potential harm that mouldy or damp living environments can cause, particularly if you’re already trying to manage respiratory conditions or allergies.
4. Outdoor pollution coming in from outside.
Outdoor air pollution, such as noxious traffic fumes, can flow into a building (15) through windows, doors, vents and any other openings, and is especially relevant to those living in towns and cities. Dangerous contaminants and pathogens, like radon, asbestos, formaldehyde and lead can enter in a similar way - travelling from the outside in. Numerous studies (16) have highlighted the health hazards associated with outdoor air pollution, linking it with conditions ranging from dementia (17) to cancer (18) and even depression. (19)
Looking at the link between air pollution and mental health, scientists (20) found that children living in the most polluted areas at age 12 were three to four times more likely to have depression by 18, compared with those living in the least polluted areas. Supporting this link, research (21) just published in PLOS Biology Journal found that countries in the bottom seventh for air quality had a 27% higher rate of bipolar disorder than those with best air quality. Such worrying evidence led the UK government to admit (22) that “air pollution continues to shorten lives, harm our children and reduce quality of life”.
Whilst outdoor air pollution – particularly for those living in traffic-ridden, urban areas – can be detrimental to indoor air quality, this does need to be weighed up against the significant benefits of ventilation (using open windows, for example), which helps to reduce (23) any accumulated levels of pollutants originating from objects or products used indoors.
5. Smoke from tobacco, cooking and fireplaces.
Whilst not a constant source of contamination (as cookers are not on all the time and people only smoke intermittently), it’s worth considering the amount of smoke in your home – particularly if you are, or live with, a tobacco smoker. Tobacco smoke contains thousands of chemicals – more than 70 of which can cause cancer, (24) and many of which irritate the lungs and airways. All of the same adverse health impacts that apply to tobacco smoke outdoors, apply inside your home – but even more so, given that you are boxed into a confined space.
Secondhand tobacco smoke has been shown to contain tiny particles that can harm (25) the lungs, and is classed as a human carcinogen by the National Toxicology Programme. In fact, when scientists from University College London published a paper (26) looking at air quality and its associations with behavioural problems in early childhood, they found that secondhand smoke exposure in the home was a consistent risk factor in emotional, conduct and hyperactivity problems in young children.
Tobacco smoke indoors, and tobacco smoke residue (chemicals that stick to surfaces and dust for months after the smoke is gone) are also widely acknowledged to be triggers for allergies and asthma; (27) causing wheezing, coughing and asthma attacks.
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(1) https://www.epa.gov/indoor-air-quality-iaq/volatile-organic-compounds-impact-indoor-air-quality (2) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2796751/ (3) https://www.ncbi.nlm.nih.gov/pubmed/11477521 (4) https://indoor.lbl.gov/sites/all/files/lbnl-47713.pdf (5) https://www.epa.gov/indoor-air-quality-iaq/volatile-organic-compounds-impact-indoor-air-quality (6) https://www.epa.gov/indoor-air-quality-iaq/volatile-organic-compounds-impact-indoor-air-quality (7) https://www.allergyuk.org/information-and-advice/statistics (8) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5219738/#CR1 (9) https://www.aafa.org/allergic-asthma/ (10) https://www.biolab.co.uk/docs/mycotoxins_ds.pdf (11) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC145304/ (12) https://www.tandfonline.com/doi/abs/10.1080/00039896.2003.11879140 (13) https://www.tandfonline.com/doi/abs/10.3200/AEOH.58.8.452-463 (14) https://www.ncbi.nlm.nih.gov/pubmed/30987624 (15) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2796751/ (16) https://www.theguardian.com/society/2019/aug/20/growing-up-in-air-polluted-areas-linked-to-mental-health-issues (17) https://bmjopen.bmj.com/content/8/9/e022404 (18) https://www.theguardian.com/environment/2013/oct/17/air-pollution-causes-cancer-world-health-organisation-who (19) https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3000353 (20) https://www.sciencedirect.com/science/article/pii/S016517811830800X (21) https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3000353 (22) https://www.gov.uk/government/news/government-launches-world-leading-plan-to-tackle-air-pollution (23) https://www.cpsc.gov/Safety-Education/Safety-Guides/Home/The-Inside-Story-A-Guide-to-Indoor-Air-Quality/ (24) https://www.aafa.org/secondhand-smoke-environmental-tobacco-asthma/ (25) https://newsinhealth.nih.gov/2018/09/breathe-easier (26) https://www.ncbi.nlm.nih.gov/pubmed/30987624 (27) https://www.aafa.org/secondhand-smoke-environmental-tobacco-asthma/ .au/