Although for most people the term "air pollution" conjures up such images as smog hovering over a city or black smoke pouring into the sky out of heavy industrial buildings, the fact is that air pollution is an indoor phenomenon as well, and one that can affect unsuspecting people while they work, when they go out to eat or find entertainment, and even when they are in their homes. And though it is very easy to fail to notice it compared to more visible or dramatic threats to our well-being, indoor air pollution can pose serious health risks when we are exposed to too much of it.
2.7% of the entire global burden of disease is caused by exposure to indoor air pollutants - World Health Organization
The World Health Organization claims that 2.7% of the entire global burden of disease is caused by exposure to indoor air pollutants. This seems even worse when we consider how easy it is to take certain steps to reduce indoor pollution, such as not smoking, maintaining proper ventilation, and using an air filter.
What causes this too-often overlooked phenomenon? There are many causes of air pollution in homes, workplaces, and elsewhere. These sources are very diverse and sometimes pose different kinds and degrees of health risks. To gain a fuller understanding of the magnitude of the problem, it will perhaps be helpful to examine some of causes of air pollution inside buildings.
According to the U.S. Consumer Product Safety Commission and the Environmental Protection Agency, indoor air pollution primarily results from "sources that release gases or particles into the air." These can include fairly common household combustion sources such as fireplaces and those chemicals that are used in indoor cooking, such as the gas in a gas oven. Other chemicals are released by building materials, most infamously asbestos, but also paint, certain types of pressed wood used to make furniture, and even wet carpets. Household cleaning or personal grooming products are other common ways that we introduce chemicals into our environment without giving the matter much thought. Heating and air conditioning devices can also contribute to indoor air pollution, as can humidifiers.
The consumption of tobacco while indoors also contributes to air pollution. As if the health problems that directly result from smoking were not enough, we must also consider the threat posed as a result of consuming tobacco products inside. Sadly, the health detriments of smoking do not stop when the cigarette (or cigar, or pipe) goes out. Exposure to second-hand smoke that has built up inside a home or business where smoking has occurred is highly dangerous.
For example, the EPA estimates that second-hand smoke is responsible for causing or worsening asthma symptoms for up to a million children every year, as well as causing respiratory infections that annually send thousands of children to the hospital and affect hundreds of thousands more. Among adults, second-hand smoke can cause problems like lung cancer and heart disease. These facts make smoking in a confined area a very risky proposition, especially when one considers how easily it can be avoided.
Other sources of air pollution are the various life forms we unwillingly share our buildings with. These include pests, mold, bacteria, and plants. Cockroaches and dust mites, for instance, are not undesirable just because they are ugly and germ-ridden. They also leave behind allergens wherever they go. These allergens settle onto surfaces such as the floor or furniture. Although they do not stay floating in our indoor atmospheres for long, when we vacuum or dust, we stir these particles up and release them once again into the air, where we, or those we share our living or working space with, can inhale them. According to the American Lung Association, this debris can trigger allergic reactions and asthma attacks, and may even be responsible for causing asthma to develop among the very young.
Nor do air pollutants come only from unwelcome "guests" like mites and roaches. Unfortunately, pets too cause similar problems by leaving dander behind them. In fact, the ALA points out, many of the harmful substances released by dogs and cats are lighter in weight than those released by the pests discussed above. This means that they are constantly floating in the air and do not need to be stirred up by human activity. Inhaling this matter can cause irritation of the respiratory system, rashes, and lung damage.
As might be expected, poor ventilation and filtration will greatly exacerbate the pollution caused by indoor air pollutants by trapping them inside. A poorly ventilated fireplace, for example, or an air conditioning unit whose owner does not regularly replace its filter as directed by the manufacturer, can become seriously detrimental to the air quality of a home. The air inside will become saturated with chemicals, such as carbon monoxide or nitrogen dioxide, that can irritate the eyes or throat, and that are capable of causing serious health problems, including bronchitis and lung cancer.
So far we have discussed common causes of indoor air pollution that originate from within the building itself. On top of these indoor sources, however, outdoor air pollutants can easily find their way inside as well. Most of the usual outdoor air pollutants can end up causing pollution indoors as well. Outside air will infiltrate an enclosed space through many avenues: open doors and windows are obvious examples, but even small cracks in walls, floors, and ceilings let outside substances in. Fans and other ventilation systems stir up the air, which moves from room to room as well as from the outside in.
These are only some of the more common causes of indoor air pollution. Some of them, such as smoking, can be remedied through simple means, but others are best combated through the use of an air purifier, which removes toxins from the air before they reach your lungs.
Air purifiers can help with some of these problems (i.e. pollen, some tobacco smoke, some airborne mold & bacteria particles) but are not a total solution. Removing pollutants at the source wherever possible and giving your home proper ventilation are the best solutions.