Environmental Pollution Education

What Are the Natural Causes of Environmental Pollution?

There are both natural occurring and human-caused sources of environmental pollution.

This article will help explain the natural causes of environmental pollution.

In this article, we’ll answer:

What Is Natural Pollution?

Pollution is a broad term that includes substances or energy released into the environment that cause harm. You may think of pollution as being only a human activity (anthropogenic). However, pollutants can also come from natural sources, such as the ash and gases released into the air during wildfires or volcanic eruptions. 

What Are Some Causes Of Natural Pollution?

Volcanic Activity

Volcanoes can release pollutants to the air in the form of gases and ash. 

The major components of volcanic gas are: 

  • water vapor 
  • carbon dioxide 
  • sulphur dioxide 
  • potentially hydrogen sulphide and halides 

Harmless water vapor is the largest component of volcanic gas, however, the other gaseous and ash components can cause harm to humans, livestock, agricultural land and water sources. Volcanic sulphur dioxide emissions (volcanic smog, also known as vog) reduce air quality locally causing concern for public health, and will even alter the global climate if the eruption is large enough. 

Carbon dioxide is a greenhouse gas released from active volcanoes, however, context is important – the Earth’s volcanic activity contributes less than 1% of the amount of carbon dioxide produced by human activities. 

Contamination of water is another potential harm associated with volcanic activity. Plumes of gas and ash can significantly alter rainwater chemistry, creating acid rain and depositing other elements created during the eruption. Some soils will leach elements, such as selenium, when contacted by acid rain, which have the potential to contaminate groundwater. 

Further to this, volcanic ash may be coated with toxic hydrogen halides that can also be poisonous to drinking water supplies. Water that collects in active volcanic craters may accumulate dissolved gases and minerals. Kawah Ijen, a crater lake in East Java, carries high loads of sulphur, ammonia, phosphates and metals (such as Cl, F, Fe, Cu, Pb, Zn, Al), and has an extremely low pH (<0.3).  The lake contaminates a nearby stream that causes harm to downstream agricultural lands.

Ash particulates from volcanic eruptions may have far-reaching impacts through atmospheric transport. A volcanic eruption in Iceland in 2010 caused an ash plume that traveled over Europe, prompting airplanes to be grounded due to concerns over how ash damages airplane engines. 

Wildfires

Naturally occurring wildfires are primarily started by lightning strikes and are another source of harmful gases and ash. In the western US, wildfires contribute significantly to atmospheric pollution by the creation of nitrogen oxides, carbon dioxide, carbon monoxide and ozone. 

Runoff from wildfire burn areas in Mediterreanean Europe has been shown to reduce the activity of stream invertebrates that shred detritus and are important to ecosystem function. Wildfires also create particulate air pollution in the form of ash that are damaging to human health. 

Though wildfires can be harmful, there are some species that have evolved to rely on natural wildfires, or the resulting succession of the forest, for their life cycles.

Oil Seeps

The fossil fuels that humans gather from geological sources also naturally leak out of the earth in certain locations, called seeps. 

The largest and most well studied oil seep is the Coal Oil Point Seep of California, where petroleum and gases bubble to the surface of the ocean from a source 1500m below the seafloor. This seep is estimated to have been active for as many as 500,000 years, creating oil slicks that are visible on the surface of the ocean and oil deposits that wash up on beaches in the form of tar balls. This seep also releases methane and reactive organic gases (ROGs) like propane and butane that are precursors to the pollutant ozone. 

Why Should You Care About Natural Pollution?

Not only is it scientifically fascinating to learn about the destructive forces of nature and the resilience of life on Earth, it is also highly informative. These events further our understanding of how to mitigate similar anthropogenic pollutants, as well as how to manage public health.

Studying natural sources of pollution may lead to finding resilient local populations, or discovery of organisms that may lead to solutions to mitigate anthropogenic pollution. For example, marine microbial communities associated with oceanic oil seeps are known to be capable of biologically degrading many (though not all) hydrocarbon compounds. There have also been recent discoveries in natural ocean hydrocarbon cycling that may lead to advances in responding to oil spills. 

Understanding air pollution from both natural and anthropogenic sources is important for public health. By studying the atmospheric contributions of natural events like wildfires and volcanoes, we are better prepared to respond effectively. 

You can educate yourself on the latest science related to sources of indoor and outdoor pollution that you may be exposed to in your area using guides made by the Environmental Protection Agency (EPA). Tools like AirNow also enable you to explore and track your real-time air quality index.

The Feedback Loop

Some natural sources of pollution are becoming more common and extreme due to climate change. Human sources of air pollution (smog, soot, and other hazardous compounds from gas and coal combustion) are the major contributing factor to climate change and they also create a feedback loop that further accelerates climate change. 

Climate change is in turn making some natural events, like wildfires, more frequent or severe.  Although wildfires can occur naturally, climate change is leading to extended droughts that lengthen the fire season and increase the severity of wildfires. It is estimated that human contribution to climate change has doubled the amount of forest fire area in the western US since 1984.

Airborne pollen allergens is another example of the interaction between climate change and natural pollutants. The rising carbon dioxide level in the atmosphere and increasingly warmer temperatures related to climate change act together to extend the pollen production season, range, and the load of pollen allergens such as ragweed.

What Can You Do About It?

Some natural pollution sources, such as volcanoes and petroleum seeps, will happen on their own cycles regardless of our actions. However, we can address the interaction between human driven climate change and natural events.

We should all use best practises to minimize the occurrence of human ignited wildfires. In the US, only about 45% of wildfires are known to be initiated from natural causes, while the rest are human-related or unknown in origin. The most common human ignition sources of wildfires are equipment, campfires, smoking, railroads, and arson. 

It’s important to always check with the appropriate local authorities about fire risks before Having any campfires, abide by any active fire restrictions, and use safe practises during drought or wildfire season in fire prone areas. 

More generally, doing our part to reduce the use and burning of fossil fuels that contribute to climate change involves: 

  • Cutting our energy demands – think reducing building heating and cooling demands, appliances, and driving less miles. 
  • Use or demand renewable energies where and when we can from our energy providers
  • Support decarbonizing fuels and net-zero carbon energy wherever possible
  • Buy local foods whenever possible, which don’t require as much transportation energy to reach you

If you are interested in learning about other ways to reduce your carbon footprint, check out the EPA carbon footprint calculator.

Team Writer

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