Air Pollution: Understanding The Toxic Air We Breathe

Air pollution is a significant environmental health hazard that affects both indoor and outdoor environments. It is caused by the presence of harmful substances in the air, including solid and liquid particles, gases, and chemical, physical, or biological agents. These pollutants can be released into the atmosphere through human activities, such as burning fossil fuels, industrial processes, transportation, and agriculture, as well as natural sources like wildfires, dust storms, and volcanic eruptions. The contamination of the air by these pollutants has detrimental effects on human health, contributing to respiratory diseases, cardiovascular issues, and even premature deaths. Addressing air pollution through interventions, policies, and sustainable practices is crucial to mitigate its impact on global health and the environment.

Natural sources of air pollution

While most harmful air pollution is caused by human activity, natural sources of air pollution are varied and include wildfires, sandstorms, sea spray, volcanoes, vegetation, decomposition, lightning, radon gas, and methane. These natural sources release pollutants that affect air quality and can pose health risks and contribute to climate change.

Wildfires

Wildfires are one of the largest sources of black carbon, which is very harmful to human health and the environment. Black carbon, or soot, can lead to lung and heart disease and premature death. It reduces sunlight, impacts plant ecosystems, and absorbs solar heat, contributing to global warming at a rate up to 1,500 times greater than that of CO2. Wildfire air pollutants can cause a range of adverse health effects, including difficulty breathing, an increased risk of asthma, heart failure, and premature death. While wildfires can be a natural phenomenon, largely human-driven global warming has exacerbated their frequency and intensity.

Volcanoes

Volcanoes emit massive amounts of sulphur dioxide, hydrogen sulfide, radon, sulfuric acid, hydrogen, carbon monoxide, hydrogen chloride, hydrogen fluoride, and helium into the atmosphere. Large amounts of harmful gases and smoke are released, which can increase background pollution levels for years, even in areas far away from the original source. Volcanoes used to be the main source of atmospheric sulphur dioxide.

Vegetation

Organic compounds from plants can be a source of air pollution. In dry regions lacking vegetation, such as deserts, high winds can lift sand and dust particles into the air, causing storms of particulate matter.

Livestock

Animals like cows and sheep release large amounts of methane through belching and flatulence. Methane is a colourless gas produced in their stomachs when bacteria break down the food they eat. Livestock is the biggest source of methane worldwide. Methane is the second most important greenhouse gas, which can cause climate change.

Other Natural Sources

Other natural sources of air pollution include sandstorms, sea spray, decomposition, lightning, and radon gas. Additionally, air pollution can be caused by the wind, which can move air pollutants short or long distances before they cause harmful impacts.

Fossil fuels and industry

Fossil fuels are a major contributor to air pollution. When fossil fuels are burned, they release large amounts of carbon dioxide, a greenhouse gas, into the air. This contributes to global warming and climate change. In fact, fossil fuels are currently the source of around 80% of the world's energy. Fossil fuel emissions must be halved within the next decade if global warming is to be limited to 1.5°C above pre-industrial levels.

The combustion of fossil fuels releases harmful pollutants, including particulate matter, carbon monoxide, ozone, nitrogen dioxide, and sulfur dioxide. These pollutants have significant health impacts, causing respiratory and other diseases. Exposure to fine particulate matter, or PM 2.5, from burning fossil fuels has been linked to approximately 8.7 million deaths globally in 2018, with some sources stating this number is even higher. This accounts for about one in five deaths worldwide, making it the leading cause of premature deaths. The health impacts of fossil fuel pollution disproportionately affect low-income communities and communities of color, with higher exposures to particulate matter pollution.

In addition to the health risks, air pollution from fossil fuels has environmental consequences. It contributes to the formation of smog and acid rain, which can damage crops, forests, and harm wildlife. Furthermore, the extraction, transportation, and refining of fossil fuels can lead to oil spills, which have devastating effects on ecosystems, shorelines, and communities.

To address the issue of air pollution from fossil fuels, businesses and governments must take action. Businesses can reduce nutrient pollution by managing and reducing emissions, increasing energy efficiency, and buying renewable energy. Governments can implement policies to support sustainable land use, cleaner energy and transport, energy-efficient housing, and better waste management. Additionally, transitioning from fossil fuels to renewable energy sources can provide immediate health benefits and reduce the number of premature deaths attributed to air pollution.

Health risks

Air pollution is the presence of one or more contaminants in the atmosphere, such as dust, fumes, gas, mist, odour, smoke or vapour, in quantities that can be harmful to human health. It is the single largest environmental health risk in Europe and the fourth-largest risk factor for early death globally.

Fine particulate matter (PM2.5) is the air pollutant driving the most significant health problems and premature mortality. In 2021, 97% of the urban population was exposed to concentrations of fine particulate matter above the health-based guideline level set by the World Health Organization (WHO). In 2020, approximately 238,000 premature deaths were attributable to PM2.5 in the 27 EU Member States.

Both short- and long-term exposure to air pollution can lead to a wide range of diseases, including stroke, chronic obstructive pulmonary disease, trachea, bronchus and lung cancers, aggravated asthma and lower respiratory infections. The International Agency for Research on Cancer has classified air pollution, in particular PM2.5, as a leading cause of cancer. Other health risks associated with air pollution include oxidative stress, inflammation, immunosuppression, and mutagenicity in cells throughout the body, impacting the lungs, heart, and brain, among other organs.

Children, the elderly, and pregnant women are more susceptible to air pollution-related diseases. Genetics, comorbidities, nutrition, and sociodemographic factors also impact an individual's susceptibility. Air pollution is associated with adverse pregnancy outcomes, such as low birth weight, pre-term birth, and small for gestational age births. It may also affect neurological development in children, increasing the risk of cognitive and emotional problems later in adolescence.

In addition, socioeconomic factors play a significant role in air pollution exposure and health risks. Historically, racist zoning policies and discriminatory lending practices have resulted in polluting industries and highways being located closer to low-income neighbourhoods and communities of colour, leading to disproportionate health impacts on these communities. Lower socio-economic status is linked to increased exposure to air pollution, with poorer individuals facing higher levels of pollution from living near busy roads or industrial areas.

Air pollution in cities

Air pollution is the contamination of the indoor or outdoor environment by any chemical, physical, or biological agent that modifies the natural characteristics of the atmosphere. It is a mix of hazardous substances from both human-made and natural sources. Air pollution is now the world's fourth-largest risk factor for early death, causing around 7 million premature deaths annually.

Cities are hotspots for poor air quality. Urban areas are particularly affected by two main pollutants: ambient (outdoor) fine particle air pollution (PM2.5) and nitrogen dioxide (NO2). PM2.5 is composed of chemicals such as sulfates, nitrates, carbon, or mineral dust. Because of their size—2.5 micrograms or smaller—these particles can easily enter the lungs and, in some cases, the bloodstream, causing serious health problems. NO2 is also linked to asthma symptoms and the development of asthma in children. Cities in South Asia, East Asia, Southeast Asia, West Sub-Saharan Africa, and Andean and Central Latin America have the highest levels of PM2.5 exposures. Almost all people living in large cities are breathing high levels of NO2.

The primary sources of human-made air pollution in cities are vehicle emissions, fuel oils, and natural gas used to heat homes, as well as by-products of manufacturing and power generation. Transportation accounts for about half of the emissions in cities, with diesel-fuelled vehicles being a significant contributor. Urban population growth and changes in land use due to increasing urban areas have also led to higher emissions of air pollutants.

Local policies and initiatives have helped improve air quality in some cities. For example, the Clean Air Fund's Breathe Cities initiative supports cities worldwide in cutting air pollution and climate emissions. In the UK, the creation of Clean Air Zones in several cities has the potential to save millions of lives. The World Health Organization (WHO) also provides technical support and guidance to its member states to address the health risks associated with air pollution.

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 worldwide. The World Health Organization (WHO) reports that 99% of people breathe air that exceeds its guideline limits for pollutants. Strategies to reduce air pollution include:

Sustainable Land Use

Implementing policies that support sustainable land use can help to reduce air pollution. This includes initiatives such as cleaner household energy sources, sustainable transport systems, energy-efficient housing, and improved municipal waste management.

Pollution Prevention

Pollution prevention approaches aim to reduce, eliminate, or prevent pollution at its source. This can be achieved by using less toxic raw materials or fuels, adopting less polluting industrial processes, and improving the efficiency of production processes. For example, using cleaner fuels and implementing emission controls on vehicles can help to reduce transportation emissions.

Regulatory Measures

Emission reduction regulations have been shown to positively impact air quality. Regulatory measures such as economic incentives, including emissions trading and caps, can be implemented to encourage the adoption of cleaner technologies and reduce pollution levels.

Control Strategies

Developing and implementing control strategies is essential for achieving air quality goals. This includes identifying priority pollutants, determining control measures, and establishing implementation plans. Public involvement in the development of control strategies can help streamline implementation and ensure the inclusion of relevant factors such as ambient air quality conditions, meteorological conditions, and noise levels.

Health Initiatives

WHO promotes interventions and initiatives for healthy sectoral policies, including energy, transport, housing, and urban development. These initiatives aim to address the key risks associated with air pollution and contribute to achieving health co-benefits from climate change mitigation policies.

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