Is Acid Rain Dangerous? Acid Rain Effects on Humans and Our Environment

Fact checked by Olga Sadouskaya, MD
Clinical Pharmacologist, Chief Medical Officer

When you think of acid rain, what comes to mind? Dead plants, burning skin, and corroded metal? That’s what we see on TV, but is it the real deal? Let’s break down the effects of acid rain on humans and the environment, and answer the question — is acid rain actually dangerous?

Causes of acid rain

All rainwater is slightly acidic, but certain chemicals can increase its acidity, making it harmful to the environment. Acid rain occurs when sulfur dioxide (SO2) and nitrogen oxides (NOX) mix with water, oxygen, and other chemicals in the atmosphere, forming sulfuric and nitric acids, which then fall to the ground in the form of acid rain.

The sulfur dioxides and nitrogen oxides required to form acid rain can be released through natural processes like volcanic eruptions, but their primary sources are man-made. Some examples include:

  • Coal and oil burning to generate electricity;
  • Exhausts from traffic;
  • Exhausts from industries and heavy equipment.

Although these gasses often originate in urban areas, they can be spread over long distances by the wind. So acid rain can be a problem for everyone, not just for those living in big cities.

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Where does acid rain occur?

Acid rains are pretty common worldwide, especially in densely populated areas with developed infrastructure and industries, like the North-Eastern part of the United States, Eastern Europe, China, and India. In Europe during the 1970s and 1980s, one area was particularly affected by acid rain: the so-called "Black Triangle" covered parts of Germany, Poland, and the Czech Republic. To this day, you can still see entire forests that are dead or dying as the result of acid rains.

Dying forests as a result of acid rain effects of trees

How does acid rain affect the environment?

The sulfur dioxides and nitrogen oxides in acid rain change the pH level of water and soil, making them more acidic, affecting plants, fish, and other wildlife. While some plants and animals can tolerate a certain amount of acidic water, the more acid is introduced to the ecosystem, the more damaging it becomes. Generally, the young of the species are more sensitive to the changing pH. Some fish eggs, for example, cannot hatch at lower pH.

Dying trees with brown leaves are also common in areas affected by acid rains.

This happens because acid rain removes necessary nutrients from the soil, making the trees weak and unable to absorb sunlight or tolerate cold temperatures. Acid rain has a great impact on the ecosystem and can leave whole lakes, rivers, and forests devoid of life.

What can acid rain damage?

Although acid rains have a greater impact on vegetation and wildlife, they can also damage buildings and man-made structures. This often happens due to so-called ‘dry deposition’. When dust particles become acidic, they can land on buildings, statues, monuments, and other surfaces, corroding metal, damaging stone, and making paint wear out more quickly.

Acid rain and dry deposition in urban areas can lead to an increase in building maintenance costs. Another concern is the loss of historical monuments: natural stone decay combined with acidic dust and air pollution can lead to the loss of intricate details on older statues, monuments, and buildings.

Stone statues damaged by acid rain

How does acid rain affect humans?

Acid rain sounds scary, and you might be wondering what it can do to your body. Fortunately, it has no direct effects on human health — walking in acid rain is no more harmful than walking in normal rain. It’s not acidic enough to burn or hurt your skin, either.

At higher altitudes, however, acid rain can create a thick, acidic fog that may irritate the eyes and nose.

The main health risks of acidic rains come from the chemicals that cause them — sulfur dioxide and nitrous oxides. When they are airborne, they can get into your lungs and increase the risk of respiratory conditions like asthma, bronchitis, and emphysema. Some studies have also found a link between these pollutants and increased risk and severity of heart disease.

How to protect yourself from acid rain

Fortunately, acid rains have become less frequent thanks to several environmental regulations. For example, in North America, the Canada-United States Air Quality Agreement of 1991 helped reduce harmful industrial practices that could lead to acid rain.

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Still, if you live in an area that can be affected by acid rain, you want to be prepared. The best way to protect yourself from the effects of acid rain is to check the forecast and air quality index. It may be best to stay indoors on days with high air pollution levels if you have asthma or other respiratory conditions. Consider getting an air purifier and regularly change the filters to ensure the air in your home is clean. If you’re going outside, you don’t need any special gear to protect you from the acid rain — your usual raincoat, umbrella, and boots should do the trick.

Key takeaways

Acid rain is usually caused by industrial pollutants, so it’s more common in urban areas and industrial centers. Fortunately, in recent years acid rains have become less frequent thanks to several environmental regulations. Still, acid rains can be harmful to the environment. The chemicals in acid rains affect the ecosystem, especially plants and aquatic life. In cities, acidic dust and rainwater can damage buildings and corrode metal.

Although acid rain has no direct effects on humans, it usually brings along a higher concentration of air pollutants. This can trigger an array of respiratory conditions, so it’s best to stay indoors and invest in an air purifier to protect yourself from the effects of acid rain.

August 1, 2022