We all know that pollution is bad for the planet and our health. But what is it, and what can we do to keep the environment healthy?

Pollution occurs when the environment is altered by the release of natural or human-produced elements. These elements can be either physical matter or intangible matter. Pollution lowers the quality of the land, water, and air, and can even cause physical harm to humans, animals, and plants.

Pollution can be natural. For example, wildfires release ash and smoke that harm air quality. However, most of the pollution that causes the greatest amounts of harm is manmade, and comes from industrial processes, transportation, agriculture, and energy production.

Although all of the examples of manmade sources of pollution also create services and products that humans need, the damage that the pollution causes could seriously endanger us in the long term. We need to drive cars to travel long distances quickly and safely, but cars are responsible for the pollution that comes from the release of exhaust. We need electricity to power all of the devices we need to work, communicate, and even store food, but coal-powered plants create emissions that pollute the atmosphere. Even living, eating, sleeping, and using the bathroom creates waste and garbage that pollutes waterways and soil.

Every living creature on Earth needs clean air and water to survive and function. If we continually pollute our air and water, we limit these precious resources and we make ourselves vulnerable to illness and early death. It is extremely important that we do everything we can to minimize pollution, but first we must know how pollution occurs.

Air Pollution

Pollution in the air can sometimes get so bad that it’s actually visible. When you see a truck on the freeway with smoke coming out of the exhaust pipe, or big factories and industrial plants with huge exhaust chimneys pouring fumes into the air, you’re seeing pollution occur before your eyes. You might have even noticed that you can’t see the mountains or buildings on the horizon through the thick layer of smog on some days. While most of the pollution in the air cannot always be seen, it’s still very dangerous.

Regions where the air is most polluted often have higher rates of respiratory illnesses among the people who live there. These illnesses include asthma, bronchitis, and even lung cancer.

The type of air pollution can sometimes be exceptionally dangerous. Although most people who live in places with high amounts of air pollution can become sick after many years, sometimes the poison in the air is so toxic it causes immediate illness and sometimes death. People in a small town in Pennsylvania in 1948 became extremely sick from a poisonous cloud from the nearby industrial plants. Nearly 40 people died in less than a week from the pollution. In Bhopal, India, toxic gas released from a local pesticide manufacturing plant killed nearly 10,000 people in only a few days. Hundreds of thousands of other people became extremely sick and suffered from permanent medical conditions.

Water Pollution

Pollution in the water supply isn’t always easy to spot. Sometimes, polluted water is discolored and cloudy, and sometimes it’s perfectly clear. Sometimes, polluted water tastes bad, and sometimes it tastes fine. This is because the harmful chemicals and particulates can’t necessarily be detected without performing scientific analysis.

When water has been polluted, it’s not safe to drink, but it’s also not safe to swim in or bathe in. According to reports from UNICEF, approximately 6,000 children die from waterborne illnesses every day. Not only are these deaths caused by drinking the water, they are also caused by eating the fish that live in polluted water.

Although sometimes water pollution occurs naturally, many water sources are polluted due to human behaviors. The chemicals used in factories are sometimes dumped into local rivers and streams. Even if they are not deliberately poured into the waterways, sometimes they seep into the groundwater inadvertently. Not only do the chemicals that seep into the waterways pollute them directly, some chemicals can also encourage the growth of harmful algae and bacteria that kills the aquatic fish and plants. When this occurs in a particular waterway, it is sometimes referred to a “dead zone,” because the water is no longer able to support life.

Soil/Land Pollution

The pollutants that harm the air and water are also harmful to the soil and land. When the soil has become contaminated by harmful chemicals, it causes harm to the local plants and animals, and even the people living in the region. When fruits and vegetables are grown in contaminated soil, they become dangerous for people and animals to eat.

Sometimes, the materials we use to grow our food actually harm the land we use to grow it. When we overuse chemical pesticides and fertilizers, they cause lasting damage to the local ecosystem. These chemicals don’t remain in the fields in which they were applied — they can be carried by the wind into neighboring communities and harm the people, animals, and plants that live there.

One of the most dangerous pesticides was called dichlorodiphenyltrichloroethane, or DDT for short. It was widely used to kill the mosquitoes that carried malaria in regions throughout Asia, but it was later found to cause cancer in people. The product also killed many species of birds, rendering them almost extinct. Although DDT was banned in the United States and in many other countries, it is still used to kill malaria-spreading mosquitoes.