If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Main content

Pollution and human health

It can be difficult to establish a cause and effect between pollutants and human health issues because humans experience exposure to a variety of chemicals and pollutants. Mesothelioma is a type of cancer caused mainly by exposure to asbestos. Created by Khan Academy.

Want to join the conversation?

Video transcript

- [Narrator] Hey there friends, all of my life, I've struggled with asthma. And normally it doesn't bother me too much, but when it's really cold outside, or if I've worked out really hard, my asthma symptoms get worse. When this happens, or in other words, when I get an asthma attack, the airways in my lungs become inflamed and swollen. And then also start to narrow and fill with mucus, making it harder and harder for me to breathe normally. However, it's not just the cold and CrossFit that trigger my asthma, but it's also air pollution. If I'm running around outside, or even just walking in areas where there's a lot of traffic and cars driving around, my asthma will flare up immediately. But why? Well today, we're going to learn about the connections between pollution and human health. This figure illustrates the three main sources of pollution in our surrounding environment, namely air, water, and soil pollution. Exposure to these pollutants can in turn lead to a variety of health issues and diseases. And today we're going to focus on air pollution in particular. Toxic gases, particulate matter, and chemicals released into the air can cause a variety of health issues, including respiratory and cardiovascular illnesses, as well as headaches, fatigue, cancer, nausea, and skin irritation. Yet doctors and researchers are still learning about the connections between pollutants in our environment and human health issues, mainly because we humans collectively experienced different levels of exposure to a variety of pollutants and toxins. So in short, it can be really hard to pin down the exact cause of certain diseases because pollutants and toxins can enter our bodies from the air, water and soil, as shown by this figure, which indicates the many anthropogenic sources, that is to say sources caused by human activities, of air, land, and water pollution. If we take a closer look of air pollutants in particular, we see a cluster of industrial facilities releasing chlorofluorocarbons, CFCs, which are anthropogenic compounds that contribute to ozone depletion in the stratosphere. We also see nitrous oxides and sulfur dioxide, which can contribute to air pollution as well as acid rain, and carbon dioxide, which is a common greenhouse gas. So how do these common air pollutants affect human health? One of them or well-studied connections between air pollution and human health is the link between asbestos and mesothelioma. Many studies have shown that the repeated act of inhaling or accidentally swallowing asbestos is the most common cause of mesothelioma, which is a type of cancer that develops the lining of the lungs and sometimes in the abdomen and heart as well. It might be a little difficult to see in this chest x-ray, but this area is circled in orange shows affected lung tissue where mesothelioma has started to spread. Normally the lung tissue should appear fairly transparent in x-rays, but it becomes opaque when mesothelioma is present. Asbestos is a naturally occurring mineral composed of millions of fibers which bind together to create a light yet virtually indestructible material. The fiber structure of asbestos makes it a really effective electrical insulator, and it's also heat resistant. So it was widely used in construction and fireproofing. When I was growing up, my parents actually had asbestos in their ceiling. And I also remembered that both my elementary school and middle school, which were built in the late 1970s, had gymnasiums with asbestos ceilings. But as public health awareness about the dangers of asbestos has grown, the business of asbestos removal has also grown. Although asbestos isn't commonly used anymore in construction, some consumer products can still contain trace amounts of asbestos, such as roofing materials. And sometimes when you're watching TV, you might see ads for asbestos abatement, which is the safe containment and removal of asbestos by professionals. The link between exposure to asbestos and mesothelioma has been heavily studied. And in turn, asbestos use has greatly declined over time. Unfortunately though, symptoms or signs of mesothelioma may not appear until 20 or 50 years later or more after exposure to asbestos with initial symptoms, including shortness of breath and chest pain. However, over time, as we can see in the lower part of this figure, asbestosis exposure can result in damage to and cancer of the pleura, which are membranes that cover the lungs and the inside of the surrounding chest walls. These pleura, and even the diaphragm, which helps you breathe, can become scarred, damaged, and hardened from asbestos. And of course, mesothelioma can develop too. What's even worse though is that mesothelioma is generally resistant to radiation and chemotherapy treatments. So long-term survival and cures are exceedingly rare. But mesothelioma can be diagnosed and treated early through regular cancer screenings and blood tests for those who may be most vulnerable to this cancer. That is to say folks who have had exposure to asbestos through their work like miners, factory workers, insulation, installers, and construction workers. So take a breath, take a sip of water. These are simple things that we take for granted each day, yet pollution can threaten these basic aspects of our lives. When my asthma starts to act up, I become acutely aware of just how much pollution affects my day-to-day health. And thanks to regulatory legislation like the Clean Air Act and the Clean Water Act in the United States, we have longer and healthier lives here. But this isn't the case everywhere, nor is it the case for everyone. So do your part and help to ensure safe air and water for all.