Air Pollution: Who Suffers?

Air pollution is a major environmental threat to human health, causing an estimated 6.7 million premature deaths annually. The World Health Organization (WHO) has developed global air quality guidelines (AQG) to address this issue. These guidelines are not legally binding but provide recommendations and targets for countries to improve air quality and protect public health. They are based on scientific evidence and expert evaluations, offering guidance on thresholds and limits for key air pollutants. WHO also monitors and tracks progress towards reducing air pollution and its health impacts, providing technical support and awareness initiatives to mitigate the risks associated with air pollution exposure.

WHO's Global Air Quality Guidelines (AQGs)

The World Health Organization's (WHO) Global Air Quality Guidelines (AQGs) are a set of evidence-based recommendations of limit values for specific air pollutants. The guidelines are designed to help countries achieve air quality that protects public health. They are not legally binding but can be used as a reference to set legally binding standards and goals for air quality management at the international, national, and local levels.

The AQGs provide guidance on thresholds and limits for key air pollutants that pose health risks, such as particulate matter (PM), ozone (O3), nitrogen dioxide (NO2), and sulfur dioxide (SO2). These pollutants are chosen due to their worldwide importance, but other air pollutants are also recognised as relevant. The guidelines also offer recommendations on good practices for the management of certain types of particulate matter, such as black carbon/elemental carbon, ultrafine particles, and particles originating from sand and dust storms.

The WHO updates the AQGs regularly to ensure their continued relevance and to support a broad range of policy options for air quality management in various parts of the world. The updates take into account new health studies and evidence on the adverse health effects of air pollution. The 2021 update, for example, adjusted almost all the AQG levels downwards, warning that exceeding the new levels is associated with significant risks to health.

The AQGs also include the concept of interim targets, which are "incremental steps in progressive reduction of air pollution". These targets are meant to provide achievable milestones for countries on the path towards ultimately achieving the air quality guidelines. They are particularly relevant for highly polluted areas, allowing for the development of pollution reduction policies within realistic time frames.

The WHO Global Air Quality Guidelines are an important tool in the fight against air pollution, which is one of the biggest environmental threats to human health. By striving to achieve the guideline levels, countries can protect public health and mitigate global climate change.

Air pollution's health impacts

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. According to the World Health Organization (WHO), air pollution is responsible for 6.7 million premature deaths annually, with 4.2 million of these occurring in 2019. The greatest number of these premature deaths occurred in the WHO South-East Asia and Western Pacific Regions, with 89% of premature deaths occurring in low- and middle-income countries.

The main pathway of exposure to air pollution is through the respiratory tract. Pollutants such as ozone, carbon monoxide, nitrogen dioxide, and sulfur dioxide can cause inflammation, oxidative stress, immunosuppression, and mutagenicity in cells throughout the body, impacting the lungs, heart, and brain, among other organs. Fine particulate matter (PM2.5) is of particular concern as it can penetrate deep into the lungs and enter the bloodstream, leading to systemic damage to tissues and cells. PM2.5 accounts for most health effects due to air pollution in the US. Exposure to PM2.5 has been linked to diseases of the cardiovascular and respiratory systems, including stroke, lung cancer, and chronic obstructive pulmonary disease (COPD). In 2019, 68% of outdoor air pollution-related premature deaths were due to ischaemic heart disease and stroke, 14% were due to COPD, 14% were due to acute lower respiratory infections, and 4% were due to lung cancers.

Air pollution has also been associated with developmental delays in children, as well as psychological and behavioural problems, including symptoms of attention deficit hyperactivity disorder (ADHD), anxiety, and depression. Maternal exposure to air pollution is associated with adverse birth outcomes, such as low birth weight, pre-term birth, and small for gestational age births. Exposure to both ozone and particle pollution during pregnancy is associated with an increased risk of premature birth, low birth weight, and stillbirth.

Additionally, air pollution disproportionately affects certain communities, with people of colour and those living in economically disadvantaged communities experiencing higher rates of exposure and health impacts. Practices such as redlining and institutionalized residential segregation have contributed to the disproportionate exposure of these communities to air pollution sources such as power plants, industrial facilities, and highways.

WHO has established global air quality guidelines (AQG) to provide guidance on thresholds and limits for key air pollutants that pose health risks. These guidelines offer interim targets to promote a gradual shift towards lower pollutant concentrations and their associated health benefits. For example, achieving interim target one (35 µg/m3) is estimated to save 300,000 lives worldwide annually. WHO also works to include health-relevant indicators of household and ambient air pollution exposure in the Sustainable Development Goals (SDGs), tracking progress towards reducing deaths and illnesses from air pollution, ensuring access to clean energy, and improving air quality in cities.

Reducing air pollution

Air pollution is a complex mixture of solid particles, liquid droplets, and gases. It can come from many sources, such as household fuel burning, industrial chimneys, traffic exhausts, power generation, open burning of waste, agricultural practices, and desert dust. The World Health Organization (WHO) has identified air pollution as the second highest risk factor for non-communicable diseases, and it is associated with 6.8 million premature deaths annually.

To reduce air pollution, individuals can make changes in their daily lives, such as reducing car usage, using more efficient appliances, and limiting energy consumption. For example, individuals can opt to walk or ride a bike instead of driving, purchase energy-efficient appliances, and turn off electrical items when not in use.

Local governments can also play a significant role in reducing air pollution by passing local ordinances, creating incentives for beneficial behaviors, and promoting and educating residents on best practices. For instance, local governments can offer incentives for residents to switch to electric or hand-powered lawn equipment, as gas-powered lawnmowers lack pollution control devices and contribute to air pollution.

Additionally, national and regional policy-makers can take concerted action to address major sources of outdoor air pollution, such as power generation and industrial practices. The WHO provides global guidance on thresholds and limits for key air pollutants, and the US Environmental Protection Agency (EPA) has implemented regulations to reduce emissions from large industrial facilities and vehicles.

By combining individual actions with local, national, and regional efforts, significant progress can be made in reducing air pollution and improving public health.

Air pollution sources

Air pollution is a complex mixture of solid particles, liquid droplets, and gases. It can come from many sources, both natural and human-generated. Natural sources include wind-blown dust, wildfires, and volcanoes. However, human-generated sources are more common and include household fuel burning, industrial chimneys, traffic exhausts, power generation, open burning of waste, agricultural practices, and desert dust.

Mobile sources, such as cars, buses, planes, trucks, and trains, are a significant contributor to air pollution. In the United States, mobile sources account for more than half of all air pollution, with automobiles being the primary source. Stationary sources, such as power plants, oil refineries, industrial facilities, and factories, emit large amounts of pollution from a single location and are also known as point sources. Area sources, such as agricultural areas, cities, and wood-burning fireplaces, are made up of smaller pollution sources that can have a significant cumulative impact.

Neighborhood sources, such as vehicles, local businesses, heating and cooling equipment, wood fires, and gas-powered yard equipment, are also important contributors to air pollution. Reducing pollution from these sources can be challenging due to their prevalence and number. However, larger-scale efforts, such as federal regulations requiring vehicles and equipment to be more efficient and produce less pollution, have been effective in reducing emissions. For example, the removal of lead from gasoline and the reduction of sulfur in diesel fuel have drastically reduced those pollutants in the air.

Additionally, policies supporting cleaner transport, energy-efficient homes, power generation, industry, and better municipal waste management would significantly reduce outdoor air pollution. Access to clean household energy would also help reduce ambient air pollution in certain regions. The WHO has established several targets to reduce air pollution and its health impacts, including SDG target 3.9.1, which calls for a substantial reduction in deaths and illnesses from air pollution, and SDG target 7.1.2, which aims to ensure access to clean energy in homes.

Air pollution and climate change

Air pollution is a complex mixture of solid particles, liquid droplets, and gases. It can come from many sources, including household fuel burning, industrial chimneys, traffic exhausts, power generation, open burning of waste, agricultural practices, desert dust, and more. According to the World Health Organization (WHO), ambient (outdoor) air pollution caused an estimated 4.2 million premature deaths worldwide in 2019, with 89% of those occurring in low- and middle-income countries.

WHO's Global Air Quality Guidelines (AQG) provide global guidance on thresholds and limits for key air pollutants that pose health risks. These guidelines are developed through a transparent, evidence-based decision-making process and offer interim targets to promote a gradual shift towards lower pollutant concentrations and their associated health benefits. For example, achieving interim target one (35 µg/m3) could save around 300,000 lives annually worldwide.

Climate change can also impact air quality, and certain air pollutants can, in turn, affect climate change. For instance, hot sunny days associated with a warming climate can increase ground-level ozone, a greenhouse gas, in some areas. Ground-level ozone can reduce plant growth and increase people's exposure to allergens like pollen. Regulatory initiatives, partnership programs, and individual actions can help reduce air pollutants and greenhouse gas emissions.

Furthermore, reducing air pollution offers a "win-win" strategy for both health and climate. Lowering ambient and household air pollution can reduce emissions of carbon dioxide (CO2) and short-lived climate pollutants, such as methane and black carbon, contributing to the mitigation of climate change. WHO actively monitors and tracks progress on health indicators related to air pollution, including mortality rates, to inform policies and interventions for improving air quality and public health.

WHO also promotes Sustainable Development Goals (SDGs) related to air pollution, including SDG 3 (good health and well-being), SDG 7 (affordable and clean energy), and SDG 11 (sustainable cities and communities). These goals aim to reduce deaths and illnesses from air pollution, ensure access to clean energy, and improve air quality in cities.

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