Indoor air pollutants| Atmospheric pollution| AP Environmental science| Khan Academy

Let's talk about indoor air pollution. I remember when I first heard about indoor air pollution in my AP Environmental Science class, I was a little confused. When I used to think of pollution, I would think of images like this or this. But pollution is often invisible, and it isn't just restricted to the outdoors. Indoor air pollutants can lead to serious health conditions and even death. But there are ways to identify and prevent indoor air pollution.

Let's take a look at an example. This is Ava, and let's say Ava, like many other people in the world, spends the majority of her time indoors. She works, sleeps, cooks, and eats in her home, and lately she's been experiencing headaches and she's been coughing. A possible culprit is indoor air pollution. So where could the indoor air pollution be coming from? Let's take a look at Ava's house.

Indoor air pollution can come from many different kinds of sources, both human-made and natural. Ava's furniture, paneling, and carpets could be releasing volatile organic compounds, which are often written down as VOCs. They basically include substances that form gases at room temperature, like formaldehyde. Formaldehyde is used as an adhesive in building materials and upholstery, and it can get into the air. This is the same stuff that is used to embalm and preserve dead bodies. In other words, it's not pleasant to breathe in.

The United States Environmental Protection Agency says that formaldehyde is one of the four most dangerous air pollutants in the country. Formaldehyde can make you dizzy and nauseated, and if you're exposed to enough of it, it can kill you. Indoor air pollutants can also come from Ava's house itself in the form of particulates, which are teeny tiny particles so small that they can stay suspended in the air. They can be really dangerous because they can travel deep into the lungs and damage cells. One such particulate is asbestos. It's actually, in my opinion, a really cool substance; it's an electrical insulator, and it's fireproof and acid-proof.

There was a time when many houses were being built with asbestos in its building insulation, flooring, and roofing. It's actually a natural material that's mined, and it has light, fluffy fibers that can be woven into cloth. To me, it always looks like unicorn hair, but really, it's more like evil unicorn hair. Each fiber can break into microscopic pieces that could scar your lungs and lead to lung cancer and other lung diseases.

Particulates in Ava's house could also be coming from the paint. Lead paint in Ava's house could begin to chip away and could suspend small particles in the air. These particles could cause lead poisoning, which can cause headaches and nerve and brain damage. The use of lead and asbestos has been restricted by many governments around the world, but these materials can still be found in older buildings.

Another way indoor air can become polluted is through combustion, which is to say burning stuff. Combustion can cause a wide variety of pollutants that can irritate lungs, including carbon monoxide, nitrogen oxides, sulfur dioxide, and particulates. One way that carbon monoxide can build up inside a building is from a poorly maintained furnace. Carbon monoxide molecules have a secret weapon: they can trick the proteins in your blood into thinking they're oxygen. This can cause asphyxiation, which is when the body cannot get enough oxygen, and it can be deadly.

Ava should make sure that her furnace is well maintained and serviced regularly. Combustion-related air pollution doesn't just come from furnaces, though. In less economically developed countries, families sometimes use open fires for heating and cooking. People often burn wood, peat, and even coal inside homes without the necessary ventilation to circulate and dilute the pollutants in the air. Combustion-related air pollution can also come from poorly ventilated fireplaces and tobacco smoke.

So what could Ava do to reduce combustion-related air pollution? Well, she could open the windows, and she could use fans to mix the smoke and pollution with outside air. Ava should also install a carbon monoxide detector to make sure that the air is safe. A carbon monoxide detector could also detect leaks from natural gas stoves or heaters.

It's also possible that Ava's house has natural pollutants, like mold, dust, or even radon. Mold is a type of microscopic fungus that's always floating around in the air, and breathing it in can cause itchy eyes, runny noses, and it can trigger asthma attacks. Molds love moisture, so when the air is really humid, there will be more mold spores, which is good for the molds but bad for us.

What areas of the house tend to have the most moisture? The bathrooms and the kitchen. So these areas especially need to have windows that can be opened or air fans that can draw moisture and the molds out of the house. Another kind of natural indoor air pollutant is radon, which is a radioactive noble gas. It's produced by the natural decay of radioactive rocks in the ground.

Let's say that Ava's basement has some cracks in the foundation in the walls. That would mean that when radon seeps upward through the soil, it could enter these cracks and be stuck inside Ava's house. Breathing in too much radon could damage lung tissue and even lead to lung cancer. Depending on where the house is built, some places like Ava's house are more likely to have radon than others. Ava can prevent radon exposure by sealing up the cracks in the foundation of her house and by ventilating her basement.

Some indoor air pollution requires professional remediation to get rid of asbestos, for example. An accredited asbestos abatement specialist basically shows up in a biohazard suit like this; that's how dangerous it is. For other situations, there is a simple solution to Ava's problem: ventilation. Ava could open windows on the opposing sides of her home just a crack. The outdoor air would flow in, dilute the indoor air pollutants, and carry them out of the house. This natural ventilation allows the air to circulate and reduces the buildup of indoor air pollutants.

There are a lot of ways that indoor air pollutants could sneak into Ava's house—from nature, from combustion, and from human-made items. Being aware of these sources can help Ava make sure that the air inside her house is fresh, clean, and healthy.