Natural Pollution: Is Nature Ever Truly Polluted?

Natural sources of pollution include wind-blown dust, wildfires, and volcanoes. Natural sources can be significant but do not usually create ongoing pollution problems like other source types. For example, wind-blown dust, wildfires, and volcanic ash are all considered natural sources of air pollution. Similarly, dirt, topsoil, or silt from fields or construction sites can run off into waterways, harming fish and wildlife habitats.

Forest fires

Natural sources of pollution include wind-blown dust, wildfires, and volcanoes. Natural sources of pollution can be significant but do not usually create ongoing pollution problems. However, wildfires are becoming larger and more frequent during the summer months in the United States and Canada, due in part to climate change. Warmer temperatures and persistent drought conditions make it easy for fires to start and quickly spread out of control.

The smoke from forest fires can travel thousands of miles, affecting air quality in distant regions. For example, smoke from fires in northern Canada has reached as far as North Dakota, South Dakota, Minnesota, and Iowa. During an air quality alert, it is recommended that people limit their time spent outdoors and reduce activities that contribute to air pollution, such as outdoor burning and unnecessary vehicle trips.

The impact of forest fires on air quality and human health underlines the importance of taking wildfire threats seriously and being prepared. Climate change is contributing to the increasing frequency and intensity of wildfires, with higher temperatures and earlier snowmelt creating drier conditions that prolong the wildfire season.

Volcanic activity

Volcanic eruptions release a variety of gases, including water vapour (H2O), carbon dioxide (CO2), sulphur dioxide (SO2), hydrogen sulfide (H2S), carbon monoxide (CO), hydrogen chloride (HCl), and hydrogen fluoride (HF). This combination of outgassed particles can have detrimental effects on the environment and human health.

For example, the respiratory systems of humans and animals can be severely damaged by exposure to sulphur dioxide and hydrogen fluoride. Additionally, the introduction of sulphur dioxide into water vapour in the atmosphere causes acid rain on a global scale. Sulphur dioxide also reacts with other atmospheric aerosols and can produce sulphuric acid (H2SO4), which has a cooling effect on the climate.

Volcanic carbon dioxide emissions, a greenhouse gas, have the potential to promote global warming. While human activities produce significantly more carbon dioxide than volcanic eruptions, very large volcanic eruptions can inject substantial amounts of carbon dioxide into the atmosphere.

Volcanic ash clouds can reach extremely high temperatures, up to around 1,000°C, and move at high speeds of about 700 km/h. These clouds can extend up to 50 km into the atmosphere and cause respiratory issues, eye irritation, and skin irritation in humans.

Wind-blown dust

Dust clouds crossing roadways are a huge safety hazard for drivers, causing numerous crashes, some fatal, when drivers are blinded by the sudden loss of visibility. Dust can also contaminate crops, compromising organic agricultural practices, and spread plant and animal pathogens into areas far downwind. As dust is often comprised of small particles, about 50 microns or smaller in diameter, it can be deposited directly in the human lungs through the respiratory tract, causing respiratory diseases, and can also be absorbed into the bloodstream, causing other organ diseases.

Hundreds of studies show dust’s connection to respiratory diseases, such as asthma and bronchitis, as well as cardiovascular disease. Dust storms can also carry viruses and toxic pollutants, such as heavy metals, bacteria, and poisonous minerals, which are then inhaled by people, causing severe health effects. The impacts of dust storms on human health are closely related to the fine particles they carry.

Wildfires

Natural Causes of Wildfires

Human Causes of Wildfires

However, human activity is the primary cause of wildfires, with human carelessness being the biggest contributing factor. This includes unattended campfires, discarded cigarettes, equipment malfunctions, and arson. For example, the Ham Lake fire in 2007, which burned down hundreds of properties and 75,000 acres of forest, was caused by an unattended campfire. In 2017 in the US, forest fires caused by discarded cigarette butts resulted in $6 billion in property damage. Arson is also a significant factor, with real estate speculation, building land reclamation, and pasture management being possible motives. According to a report, there were 52,260 intentional fires in the US between 2014 and 2018, resulting in an estimated 400 civilian deaths and $815 million in property damage annually.

Impact of Climate Change

Climate change has also played a critical role in increasing the frequency and intensity of wildfires. It contributes to longer drought periods, higher temperatures, and drier vegetation, creating ideal conditions for wildfires to ignite and spread rapidly. Research shows that in some types of forests, an average annual temperature increase of 1 degree Celsius can increase the median burned area per year by up to 600%. Additionally, the spread of insects like the mountain pine beetle, which weaken or kill trees, further adds fuel to the fire.

While wildfires can occur naturally, human activity and climate change have significantly increased their occurrence and severity. Understanding the causes of wildfires is crucial for public safety, environmental conservation, and forest management. By fostering a deeper understanding of these phenomena, we can develop more effective management and mitigation strategies to protect our planet and communities from their destructive power.

Radon gas

Radon is a naturally occurring, radioactive gas that is produced by the natural radioactive decay of uranium, which is found in all rocks and soils. It can also be found in water. Radon is a major contributor to the ionizing radiation dose received by the general population and is an important source of ionizing radiation of natural origin. It is one of the leading causes of lung cancer, accounting for an estimated 3% to 14% of all lung cancers in a country, depending on the national average radon level and smoking prevalence.

Radon is a colourless, odourless, and tasteless gas that can easily go unnoticed by occupants of buildings. It enters buildings through cracks in the floors or at floor-wall junctions, gaps around pipes or cables, and drains or spaces around foundations. The concentration of radon in buildings depends on various factors, including local geology, the routes available for radon to enter the building, radon exhalation from building materials, and the rate of exchange between indoor and outdoor air.

Radon levels are typically higher indoors and in areas with minimal ventilation, such as mines, caves, and water treatment facilities. Residential buildings, schools, and offices can have radon levels ranging from 10 Bq/m3 to more than 10,000 Bq/m3. The risk of lung cancer increases by about 16% for every 100 Bq/m3 increase in long-term average radon concentration.

To reduce radon levels in indoor settings, various corrective actions can be taken. These include increasing under-floor ventilation, installing radon sump systems, sealing floors and walls, and improving building ventilation. Preventing radon accumulation in newly constructed buildings is now included in many national building codes.

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