What Is Indoor Air Pollution? - Definition, Sources & Effects

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Lesson Transcript
Instructor: Sarah Friedl

Sarah has two Master's, one in Zoology and one in GIS, a Bachelor's in Biology, and has taught college level Physical Science and Biology.

In this video lesson, you will learn the harmful effects of indoor air pollution. You will also gain an understanding of the sources of indoor air pollution, and how they differ between developed and developing nations.

Indoor Air Pollution

When you think of air pollution, you probably think of things like smog, power plants and emissions from cars and trucks. Those are all examples of outdoor air pollution, but air indoors can be polluted, too. Pollutants are any harmful contaminants in the air; therefore, indoor air pollution is when pollutants from things such as gases and particles contaminate the air indoors.

Indoor air pollution is a very real and dangerous thing because indoor air is far more concentrated with pollutants than outdoor air. It's estimated that 2.2 million deaths each year are due to indoor air pollution (compared to 500,000 deaths from outdoor air pollution). There are many sources of indoor air pollution, but they are different for developed and developing nations. We'll first look at developing nations to see how indoor air becomes polluted in these locations. Then, we'll explore what causes indoor air pollution in developed countries.

Indoor Air in Developing Countries

Indoor air pollution has a far greater impact on developing countries than it does on developed ones because fuel, such as wood, charcoal and animal dung, is burned inside homes for cooking and heating. Rarely is there proper ventilation to allow the pollutants to escape, so residents of these homes end up breathing in carbon monoxide and other dangerous contaminants.

Indoor air pollutants from indoor fuel burning lead to serious human health problems, such as pneumonia, bronchitis, cancer, heart disease and asthma. And, since more than half of the population of developing nations has no other method for cooking and heating, it's not surprising that indoor air pollution from indoor fuel burning kills 1.6 million people each year.

Indoor Air in Developed Countries

Consider this: The average American spends about 90% of their lives indoors. Put this with what you now know about how polluted indoor air can be and that creates a dangerous situation! For developed nations, such as the U.S., the two most dangerous indoor air pollutants are tobacco smoke and radon.

Even if you are not a smoker, secondhand smoke can cause many of the same health problems as directly inhaling from cigarettes - things like lung cancer, emphysema, asthma and heart disease. Even if inhaling secondhand, you are still taking in over 4,000 chemicals, a large number of which are carcinogens, or cancer-causing chemicals.

Radon gas is also harmful indoors, and it is the second-leading cause of lung cancer in the U.S. (tobacco smoke is the first). Radon gas is a radioactive gas that comes from the natural breakdown of uranium in soil, rock and water. When the uranium breaks down, the radon gas seeps up and can get into buildings. Radon is especially dangerous because it is both colorless and odorless, which makes it impossible to detect without special testing equipment.

In addition to tobacco and radon, volatile organic compounds (or VOCs) create a variety of pollutants in indoor air. VOCs are carbon-containing compounds that are released by pretty much anything you can imagine - perfume, paint, plastic, household cleaners, adhesives, furniture, carpet, paper…even that nice 'new car smell' is really just the smell of toxic chemicals being released!

The good thing about VOCs is that, while we really are surrounded by them, their release into the air is pretty minimal. The problem, though, is that when they are indoors they tend to be found in higher concentrations than if these small amounts were released into open space. Living things can also create indoor air pollution. Things like dust mites, pet dander, mold, mildew and airborne bacteria are all living creatures that cause human health problems by polluting indoor air. Their effects may be as benign as triggering allergies or may be as dangerous as causing infectious diseases.

Sometimes indoor air pollution causes health issues, but the source of the pollution is unknown. When this happens, it's called sick building syndrome. Sick building syndrome is tricky because people display health problems that are attributed to spending time in the building, but the exact cause of the illness (or the illness itself) isn't identifiable.

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