Air Pollution's Human Cost: Global Estimates

Air pollution is a pressing global issue, threatening the health of millions worldwide. The World Health Organization (WHO) estimates that 6 million deaths per year are linked to exposure to outdoor air pollution, with an additional 11.6% of global deaths associated with indoor air pollution. In total, air pollution is responsible for 7 million premature deaths annually. The organization has developed a strategy to raise awareness of the risks of air pollution and promote solutions to mitigate these risks. WHO's air quality model reveals that 92% of the world's population lives in areas where air quality levels exceed the recommended guidelines.

The health impact of air pollution

Air pollution is a major threat to health across the globe. According to the World Health Organization (WHO), almost the entire global population (99%) is exposed to air pollution levels that put them at increased risk of diseases including heart disease, stroke, chronic obstructive pulmonary disease, cancer, pneumonia, and acute respiratory infections. In 2019, WHO estimated that about 68% of outdoor air pollution-related premature deaths were due to ischaemic heart disease and stroke, 14% were due to chronic obstructive pulmonary disease, 14% to acute lower respiratory infections, and 4% of deaths were due to lung cancers.

The health impacts of air pollution are far-reaching and affect people in both indoor and outdoor environments. Indoor air pollution, caused by household combustion devices, can be just as deadly as outdoor air pollution. In 2012, an estimated 6.5 million deaths worldwide were associated with indoor and outdoor air pollution combined, with nearly 90% of these deaths occurring in low- and middle-income countries. The major sources of indoor air pollution include the use of polluting open fires or simple stoves for cooking fuelled by kerosene, biomass (wood, animal dung, and crop waste), and coal.

Outdoor air pollution, also known as ambient air pollution, is caused by residential energy use for cooking and heating, vehicles, power generation, agriculture/waste incineration, and industry. In 2019, outdoor air pollution was estimated to have caused 4.2 million premature deaths worldwide, with 89% of those deaths occurring in low- and middle-income countries. The greatest number of premature deaths due to outdoor air pollution was reported in the WHO South-East Asia and Western Pacific Regions.

The health impacts of air pollution are not limited to mortality but also include morbidity and reduced quality of life. Air pollution is a major risk factor for many of the leading causes of death, including heart disease, stroke, lower respiratory infections, lung cancer, diabetes, and chronic obstructive pulmonary disease (COPD). It is also one of the main contributors to the global disease burden, reducing life expectancy and causing people to live with poor health.

Addressing air pollution is crucial for protecting public health and mitigating climate change. WHO has developed and implemented strategies to raise awareness about the risks of air pollution and promote interventions for healthy sectoral policies, such as sustainable transport, clean household energy solutions, renewable energies, and improved waste management. These policies not only reduce air pollution but also offer climate benefits by lowering greenhouse gas emissions.

Air pollution and climate change

Air pollution is a major threat to health across the globe. According to the World Health Organization (WHO), 99% of the global population is exposed to air pollution levels that put them at increased risk of heart disease, stroke, chronic obstructive pulmonary disease, cancer, pneumonia, and other diseases. In 2019, outdoor air pollution was estimated to have caused 4.2 million premature deaths worldwide, with 89% of those deaths occurring in low- and middle-income countries.

Climate change can also affect air quality, and certain air pollutants can influence climate change. For example, hot sunny days associated with a warming climate can increase ground-level ozone, which is a greenhouse gas that contributes to climate change by trapping heat in the atmosphere. Regulatory initiatives, partnership programs, and individual actions can help reduce air pollutants that harm human health and contribute to climate change. For instance, providing access to affordable clean household energy solutions for cooking, heating, and lighting can reduce indoor air pollution. Similarly, shifting to clean modes of power generation, such as renewable combustion-free power sources, can reduce outdoor air pollution.

The effects of climate change on air quality vary by region. In many areas of the United States, climate change is expected to worsen harmful ground-level ozone, increase exposure to allergens like pollen, and contribute to overall poorer air quality. Extreme weather events associated with climate change, such as flooding and storm surges, can also lead to damp indoor conditions that promote the growth of harmful pollutants like mold and bacteria. Wildfires, which are becoming more frequent and severe due to climate change, release smoke that lowers air quality and harms human health.

Addressing air pollution is crucial for both public health and climate change mitigation. Most policies aimed at reducing air pollution offer co-benefits for health and climate. Lower levels of air pollution improve cardiovascular and respiratory health, while also reducing emissions of carbon dioxide (CO2) and short-lived climate pollutants like black carbon and methane. Black carbon, a component of fine particulate matter, is one of the largest contributors to global warming after CO2. Therefore, tackling air pollution not only improves public health but also helps to mitigate climate change in the near and long term.

Air pollution and income levels

Air pollution is a major threat to health across the globe. According to the World Health Organization (WHO), almost everyone on Earth (99%) is exposed to air pollution levels that put them at increased risk of heart disease, stroke, chronic obstructive pulmonary disease, cancer, pneumonia, and more. WHO estimates that in 2019, outdoor air pollution caused 4.2 million premature deaths worldwide, with 89% of those deaths occurring in low- and middle-income countries.

People living in low- and middle-income countries are typically more vulnerable to air pollution due to higher levels of exposure and a higher prevalence of diseases negatively affected by air pollution, such as asthma. Additionally, within these countries, certain populations are even more vulnerable, including those living in slums or near busy roads, lacking access to clean cooking fuels, or working in certain occupations.

Several factors related to income levels contribute to air pollution and its health impacts. For example, in lower-income neighbourhoods, residents may have limited access to clean and reliable sources of energy for cooking, heating, and lighting. They may rely on traditional fuels like wood or dung and inefficient cooking stoves, which contribute to indoor air pollution. This situation particularly affects women and children, who often spend more time in the kitchen or polluted living spaces and bear the health burdens of household air pollution.

Income-associated differences in mortality rates have also been observed. Studies have found that people with lower incomes and higher exposure to particulate pollution face an increased risk of non-accidental deaths. Furthermore, areas with higher unemployment rates and higher usage of public transportation have been linked to greater risks of premature death from air pollution.

Addressing air pollution is crucial for protecting public health, especially in low- and middle-income countries. Implementing policies and investments that support cleaner transport, energy-efficient homes, improved waste management, and access to clean household energy can significantly reduce outdoor air pollution sources. Additionally, promoting clean technologies in industries and improving energy efficiency in urban planning can help mitigate air pollution and its health impacts across income levels.

Air pollution and energy sources

The World Health Organization (WHO) estimates that in 2019, approximately 4.2 million premature deaths worldwide were caused by ambient (outdoor) air pollution. The majority of these deaths 89% occurred in low- and middle-income countries, with the highest numbers in the WHO South-East Asia and Western Pacific Regions. According to WHO, outdoor air pollution is caused primarily by exposure to fine particulate matter, which leads to cardiovascular and respiratory diseases, and cancers.

WHO also monitors indoor air pollution, which is often caused by cooking, heating, and lighting sources. In 2014, WHO issued guidelines for clean fuels and technologies for household use, aiming to reduce the health risks associated with indoor air pollution.

Energy sources play a significant role in air pollution. Oil, for example, accounts for 37% of global energy consumption and is a major contributor to air pollution during the refining process, which releases volatile organic hydrocarbons and toxic emissions. Similarly, the extraction of other fossil fuels, such as tar sands and oil shale, through strip mining has severe environmental impacts, releasing carbon dioxide, methane, and other air pollutants.

On the other hand, renewable energy sources have been shown to reduce air pollution. Solar power, for instance, releases no carbon emissions or air pollutants, although the manufacturing of photovoltaic (PV) cells can generate hazardous waste. Hydropower is another clean and renewable source of energy as it does not directly produce pollutants, and the source of power is regenerated.

To address the issue of air pollution, the transition to cleaner energy sources and technologies is crucial. This includes promoting access to affordable clean household energy solutions, shifting to clean modes of power generation, improving waste management, and adopting renewable and combustion-free power sources such as solar and wind energy. These measures not only reduce air pollution but also contribute to protecting public health and promoting carbon neutrality.

Air pollution and mortality rates

Air pollution is a major environmental risk to health, and almost all of the global population (99%) are exposed to air pollution levels that put them at increased risk for diseases including heart disease, stroke, chronic obstructive pulmonary disease, cancer, pneumonia, and respiratory disease. According to the World Health Organization (WHO), air pollution kills an estimated seven million people worldwide every year, with 9 out of 10 people breathing air containing high levels of pollutants.

WHO monitors the exposure levels and health impacts (i.e., deaths, DALYs) of air pollution at the national, regional, and global levels from both ambient (outdoor) and household air pollution. In 2019, WHO estimated that outdoor air pollution caused 4.2 million premature deaths worldwide, with 89% of those deaths occurring in low- and middle-income countries. The greatest number of premature deaths were in the WHO South-East Asia and Western Pacific Regions.

The main sources of outdoor air pollution include residential energy for cooking and heating, vehicles, power generation, agriculture/waste incineration, and industry. Household combustion devices, motor vehicles, industrial facilities, and forest fires are also common sources of air pollution. Pollutants of major health concern include particulate matter, carbon monoxide, ozone, nitrogen dioxide, and sulfur dioxide.

WHO has developed and implemented strategies to raise awareness of the risks of air pollution and to promote interventions and initiatives for healthy sectoral policies. These include policies supporting sustainable land use, cleaner household energy and transport, energy-efficient housing, improved waste management, and the use of clean technologies.

Despite the high number of deaths attributed to air pollution, there is evidence that death rates from air pollution are declining. Data scientist Hannah Ritchie argues that we are approaching "peak pollution deaths" globally. The implementation of environmental regulations and the development of low-pollution technologies have contributed to significant reductions in air pollution in many countries. For example, in the UK, emissions of local air pollutants are just a fraction of what they were in the past, with nitrous oxides down by 76% and carbon monoxide down by 90%.

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