Sources Of Pollution: Understanding The Causes

Air pollution is caused by the release of contaminants into the atmosphere, including dust, fumes, gas, mist, odour, smoke or vapour. According to the World Health Organization (WHO), air pollution is responsible for nearly seven million deaths worldwide each year. The burning of fossil fuels is a major contributor to air pollution, with vehicles, power plants and factories releasing harmful chemicals and gases into the atmosphere. Other sources of air pollution include vehicle exhaust, smoke, road dust, industrial emissions, pollen, gas-fuelled yard equipment and household chemicals. Short- and long-term exposure to air pollution can lead to a range of health issues, including respiratory problems, heart disease, stroke, lung cancer and premature death.

Fossil fuels

Fossil fuel combustion emits harmful pollutants, including nitrogen oxides, benzene, formaldehyde, and soot (particulate matter). These emissions have severe health consequences, including early death, heart attacks, respiratory disorders, stroke, and asthma. According to research, fossil fuel pollution caused approximately 8 million deaths in 2018, making it responsible for about one in five deaths worldwide. The impact of this pollution is not limited to physical health; it has also been linked to Alzheimer's disease and absenteeism at school and work.

The extraction and processing of fossil fuels also contribute to environmental degradation. Mining and drilling activities disrupt and pollute ecosystems, leading to habitat destruction and displacement of wildlife. Coal mining, for example, involves removing entire layers of soil and rock, uprooting natural habitats. Oil spills and leaks during extraction or transportation can contaminate drinking water sources and devastate freshwater or ocean ecosystems.

Furthermore, the wastewater generated from drilling, fracking, and mining operations is often laden with heavy metals, radioactive materials, and other toxic pollutants. Improper storage of this wastewater can result in leaks or overflows that contaminate waterways and aquifers. Additionally, the burning of fossil fuels releases nitrogen oxides, contributing to smog and acid rain formation.

To address these issues, a transition to cleaner energy sources, such as renewables like wind and solar power, is imperative. Improving energy efficiency and implementing regulations to reduce emissions are crucial steps toward mitigating the environmental and health impacts of fossil fuel use.

Industrial emissions

The natural gas, plastic, chemical, electric generation, and waste disposal industries can generate hazardous waste that requires proper disposal. However, the disposal process can sometimes create significant air pollution. For example, waste incineration is a major source of air pollution and climate change. Additionally, the release of volatile organic compounds (VOCs) and volatile inorganic compounds (VICs) from industrial processes can cause odour issues and negatively impact the safety and occupational health of employees.

To address these issues, governments have imposed strict environmental regulations, directing polluting activities to implement efficient gas toxic waste management procedures. Various techniques, such as physicochemical and biological waste gas treatment methods, are used to control air emissions. The European Union (EU), for instance, has set rules tackling industrial pollution through the industrial emissions directive, aiming to prevent and reduce pollution from large industrial plants. The directive covers over 50,000 plants in the EU that are responsible for emitting 20% of all air and water pollutants and 40% of greenhouse gas emissions.

Vehicle exhaust

The harmful substances emitted by vehicles include:

• Carbon dioxide (CO2) – a greenhouse gas that contributes to climate change.
• Carbon monoxide (CO) – an invisible, toxic gas that results from incomplete fuel combustion.
• Nitrogen oxides (NOx) – highly reactive gases produced during any combustion process that can contribute to smog.
• Sulfur dioxide (SO2) – a colourless gas that occurs naturally in crude oil and forms acids when burned, leading to engine corrosion and smog.
• Hydrocarbons (HC) – unburnt fuel that escapes from exhausts and evaporates from fuel tanks and nozzles.
• Benzene (C6H6) – a carcinogenic substance found naturally in petrol and diesel in small quantities.
• Particulates – airborne particles of black soot and metal emitted by diesel engines.

The health problems linked to pollutants from cars include allergies, skin irritation, heart disease, respiratory problems such as asthma, and lung cancer. Long-term exposure to diesel exhaust fumes may also increase the risk of lung cancer. Those living in densely populated urban areas are most at risk of developing health problems linked to pollution.

To reduce exhaust emissions, car manufacturers are improving engine and exhaust system design, and catalytic converters and particulate filters are now standard on all new petrol and diesel cars. Many cities have also introduced clean air zones to discourage the most polluting vehicles from entering.

Poor air quality indoors

Inadequate Ventilation:

Inadequate ventilation can increase indoor air pollution by trapping pollutants inside a building. This can happen in homes designed to minimise outdoor air infiltration or during weather conditions that reduce natural ventilation through open doors and windows.

Fuel-Burning Appliances:

Cooking stoves, furnaces, and water heaters that use fuel can emit harmful pollutants. Improperly adjusted appliances, such as gas stoves, can emit higher levels of carbon monoxide.

Building Materials and Furnishings:

Certain building materials and furnishings can release pollutants. For example, deteriorated asbestos-containing insulation, wet carpets, and pressed wood products can contribute to indoor air pollution.

Household Products:

Cleaning supplies, personal care products, and hobby-related items can be sources of indoor air pollution. Some release pollutants continuously, while others release them intermittently during use.

Outdoor Sources:

Outdoor air pollutants, such as radon, pesticides, and general outdoor air pollution, can enter buildings through open doors and windows or even on shoes, clothing, and pets.

Moisture and Mould:

Excessive moisture indoors can promote the growth of mould, dust mites, cockroaches, bacteria, and viruses, which can negatively impact health.

Volatile Organic Compounds (VOCs):

Scents and chemicals, both natural and synthetic, can be found indoors and may be harmful to health. Some common sources include air fresheners, cleaning supplies, and household chemicals.

The effects of poor indoor air quality can range from immediate reactions such as eye, nose, and throat irritation to more severe long-term health issues like respiratory diseases, heart disease, and cancer. It is important to identify and address sources of indoor air pollution to improve air quality and reduce potential health risks.

Wildfires

The gases released by wildfires, such as carbon dioxide and carbon monoxide, are significant contributors to air pollution and climate change. Carbon dioxide, a greenhouse gas, traps heat in the Earth's atmosphere, leading to global warming. On the other hand, carbon monoxide is a poisonous gas that can be incredibly harmful to human health when inhaled in high concentrations.

Wildfire smoke is a complex mixture that can contain volatile organic compounds (VOCs). These chemicals can have short-term and long-term health effects, ranging from eye, nose, and throat irritation to more severe problems like damage to the liver, kidneys, and central nervous system. Additionally, the intense heat generated by wildfires can cause the release of heavy metal pollutants from the soil, such as mercury, which can then be transported through the air and deposited in other areas, leading to environmental contamination.

The impact of wildfire smoke extends beyond air pollution. It can affect cloud formation and precipitation, resulting in thicker and more persistent clouds and potential changes in rainfall patterns. Smoke particles can also alter the amount and distribution of solar radiation reaching the Earth's surface, leading to changes in temperature and atmospheric stability, which, in turn, can influence weather systems and storm behaviour.

The health risks associated with wildfire smoke are significant. A 2024 study of the Marshall Fire in Boulder, Colorado, found that smoke and ash inside homes, even after the fire had cleared, caused symptoms such as headaches, coughing, sneezing, sore throat, and watery eyes. These symptoms persisted for up to six months after the fire, and about a third of those surveyed still reported symptoms two years later.

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