Air Pollution: A Threat To Our Planet

Air pollution is a mix of hazardous substances from both human-made and natural sources that contaminate the indoor or outdoor environment. It is a major threat to global health and prosperity, causing more than 6.5 million deaths each year globally. The burning of fossil fuels, vehicle emissions, industrial processes, waste management, and agriculture are some of the primary sources of air pollution. Particulate matter, ozone, nitrogen dioxide, and carbon monoxide are among the pollutants that contribute to respiratory diseases, heart problems, and lung cancer. Addressing air pollution through policies, sustainable practices, and cleaner technologies is crucial for protecting public health and mitigating its impact on the planet.

Natural sources of air pollution

Some natural sources of air pollution are organic compounds from plants, sea salt, suspended soils, and dust. For instance, dust from the Sahara can be transported over long distances by wind. Wind can also move other air pollutants before they cause harmful impacts.

Another natural source of air pollution is methane, which is released in large quantities by livestock such as cows and sheep. Methane is a colourless gas produced in the stomachs of these animals when bacteria break down the food they eat. Livestock is the biggest source of methane worldwide, and it is the second most important greenhouse gas, which can cause climate change.

Human-made sources of air pollution

Air pollution is a mix of hazardous substances from both human-made and natural sources. The human-made sources of air pollution are varied and numerous, with vehicles, industrial activities, and residential energy use being some of the most significant contributors.

Vehicles

Road traffic is a major source of air pollution, with cars, vans, buses, and lorries releasing pollutants from their exhausts when burning fuel. Larger vehicles with bigger engines tend to release more pollution. The pollutants emitted by vehicles include nitrogen oxides, carbon monoxide, ground-level ozone, various forms of carbon, and fine particulate matter, which can have serious health impacts, especially on vulnerable individuals.

Industrial Activities

Factories and industrial processes emit a range of pollutants, including sulfur dioxide, nitrogen oxides, particulate matter, and volatile organic compounds. The combustion of fossil fuels, such as coal, gasoline, or natural gas, in power plants, refineries, and industrial boilers also contributes to the release of pollutants, including smog and soot.

Residential Energy Use

Residential energy use for cooking and heating contributes to air pollution, particularly in households that use polluting open fires or simple stoves fuelled by kerosene, biomass (wood, animal dung, and crop waste), or coal. The combustion of these fuels releases harmful chemicals and gases, impacting the health of those exposed.

Other Human-Made Sources

Other human-made sources of air pollution include power generation, agriculture/waste incineration, chemical production, and certain industrial activities such as pulp and paper production, and the manufacturing of phosphatic fertilizers, which release pollutants like hydrogen sulfide, hydrogen fluoride, and chlorine into the atmosphere.

Health risks of air pollution

Air pollution is the presence of contaminants in the atmosphere, such as dust, fumes, gas, mist, odour, smoke or vapour, in quantities that can be harmful to human health. The health impact of air pollution exposure depends on the duration and concentration of exposure, as well as the health status of the affected populations.

Air pollution has been associated with oxidative stress and inflammation in human cells, which can lay the foundation for chronic diseases and cancer. The International Agency for Research on Cancer of the World Health Organization (WHO) has classified air pollution as a human carcinogen. Studies have established that short-term exposure to higher levels of outdoor air pollution is associated with reduced lung function, asthma, cardiac problems, emergency department visits, and hospital admissions. Mortality rates related to air pollution are also a concern, with exposure to the air pollutant PM2.5 linked to an increased risk of death.

Fine particulate matter, such as PM2.5, can impair blood vessel function and speed up calcification in arteries. It can also penetrate deep into the lungs, enter the bloodstream, and travel to organs, causing systemic damage to tissues and cells. This can lead to a range of diseases, including stroke, heart disease, chronic obstructive pulmonary disease (COPD), and cancer. Children are particularly vulnerable to the health risks of air pollution, with higher pollution levels increasing short-term respiratory infections and the likelihood of developing asthma and bronchitis symptoms in adulthood. Living in communities with higher pollution levels can also cause lung damage and cognitive and emotional problems in children.

Pregnant women are also more susceptible to the health impacts of air pollution, with exposure to TRAP increasing the risk of dangerous changes in blood pressure, known as hypertensive disorders, which are a leading cause of pre-term birth, low birth weight, and maternal and fetal illness and death. Air pollution has also been linked to an increased risk of diabetes, cognitive impairment, neurological diseases, and adverse pregnancy outcomes.

Additionally, psychosocial stress, such as poverty, racial/ethnic discrimination, and residency status, can amplify the harmful effects of air pollution. Research has shown that people of colour are more likely to be exposed to air pollution and suffer greater health harm. This is often due to systemic racism, practices such as redlining, and the impaired ability of many people of colour to build wealth and relocate to safer areas.

Overall, air pollution poses a significant risk to human health, impacting nearly every organ in the body and increasing the likelihood of various diseases and premature death.

Air pollution in cities

Air pollution is a familiar environmental health hazard. It is a major threat to global health and prosperity, causing more than 6.5 million deaths each year worldwide. Air pollution is responsible for respiratory disease, cardiovascular disease, neurological damage, cancer, and death. It is caused by burning fossil fuels for industry, construction, transportation, and heating, as well as nuclear weapons, toxic gases, germ warfare, and rocketry. The burning of fuels to produce electricity also contributes to air pollution.

Cities are hotspots for poor air quality. Urban areas are particularly vulnerable to air pollution due to several factors, including population growth, changes in land use, economic opening-up, new trading partners, and political change. Urban population growth is driven by migration from rural areas and a higher birth rate within the cities themselves, particularly in developing countries. This growth leads to increased emissions of air pollutants from various sources, such as motor traffic, industry, and power plants.

The type and level of air pollution vary among cities. Cities in high-income regions generally have lower levels of PM2.5 pollution, while cities in South Asia, East Asia, Southeast Asia, West Sub-Saharan Africa, and Andean and Central Latin America have higher levels of PM2.5 exposures. Almost all people living in large cities are breathing high levels of NO2, with 81 out of 103 cities exceeding the global average. However, it is important to note that local policies and interventions have improved air quality in some cities, while pollution has worsened in others.

Transportation is a significant source of air pollution in cities, with diesel-fuelled vehicles and congestion contributing to poor air quality. The focus on the movement of cars during urban planning and the recent increase in home deliveries have exacerbated congestion problems. Additionally, wildfires and bonfires contribute to outdoor carbon monoxide (CO) levels, further impacting air quality in cities.

Addressing air pollution in cities requires a coordinated approach that includes improving mobility, enhancing public transport, and promoting sustainable urban development. Well-planned transport systems, walkable streets, and the creation of green spaces are essential steps towards cleaner air in urban areas. Initiatives such as the Clean Air Fund's Breathe Cities partnership aim to support cities in reducing air pollution and climate emissions.

Strategies to reduce air pollution

Air pollution is a mix of hazardous substances from both human-made and natural sources. It is a major threat to global health and prosperity, causing more than 6.5 million deaths each year globally. Strategies to reduce air pollution include:

Sustainable land use

This involves promoting sustainable practices in land use, such as implementing policies that support cleaner energy sources, sustainable agriculture, and waste management practices. For example, using cleaner fuels and improving waste management practices can reduce the amount of harmful pollutants released into the atmosphere.

Cleaner household energy and transport

Encouraging the use of cleaner household energy sources, such as promoting the use of electric vehicles, cleaner fuels, and improving the energy efficiency of homes and buildings. This can reduce emissions from vehicles and power generation, which are major sources of air pollution.

Industrial process improvements

Industries can adopt less polluting processes, improve the efficiency of their operations, and use less toxic raw materials or fuels. For example, using mechanical collectors, wet scrubbers, fabric filters, and electrostatic precipitators can help control and reduce emissions.

Emission controls and economic incentives

Implementing emission controls on vehicles and industrial sources, as well as economic incentives such as emissions trading, banking, and caps, can help reduce emissions and provide financial motivation for polluters to reduce their impact.

Public involvement and compliance

Developing control strategies with public input and implementing compliance and enforcement programs can help ensure that regulations are effective and widely accepted. Early consultation with the public can streamline implementation and reduce future challenges.

Health sector interventions

The World Health Organization (WHO) promotes interventions and initiatives for healthy sectoral policies, including energy, transport, housing, and urban development. By addressing key risks associated with air pollution, such as providing guidance on healthy indoor and outdoor air quality standards, the health sector can play a crucial role in mitigating the health impacts of air pollution.

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