How air pollution is destroying our health
Air quality monitoring → Air quality monitoring in low- and middle-income countries needs to be strengthened, especially in areas close to hospitals, schools, and workplaces. Low-cost sensors and other new technologies can expand air quality monitoring and forecasting to areas that are currently underserved. New protocols and standards are needed to guide the effective use and interpretation of data produced by low-cost sensors in citizen science and other applications.
WHO data show that almost all of the global population (99%) breathe air that exceeds WHO guideline limits and contains high levels of pollutants, with low- and middle-income countries (LMIC) suffering from the highest exposures.
Ambient (outdoor) air pollution in both cities and rural areas is causing fine particulate matter which results in strokes, heart diseases, lung cancer, and acute and chronic respiratory diseases.
Additionally, around 2.6 billion people are exposed to dangerous levels of household air pollution from using polluting open fires or simple stoves for cooking fuelled by kerosene, biomass (wood, animal dung and crop waste) and coal.
First Global Conference on Air Pollution and Health
To rally the world towards major commitments to fight this problem, WHO and partners convened the first Global Conference on Air Pollution and Health in Geneva on 29 October – 1 November 2018. The conference raised awareness of this growing public health challenge and shared information and tools on the health risks of air pollution and its interventions.
This conference showcased some of WHO’s work on air pollution, including the findings of its Global Platform on Air Quality and Health. This platform, whose diverse membership includes researchers, civil society, UN agencies and other partner institutions, reviewed the data on air quality and health. For example, the platform worked on techniques to more accurately attribute air pollution coming from different sources of pollution. Ongoing work includes improving estimates of air quality by combining the data from various air quality monitoring networks, atmospheric modelling and satellite remote sensing.
Health impacts of air pollution
There are two main types of air pollution: ambient air pollution (outdoor pollution) and household air pollution (indoor air pollution). Ambient air pollution is a major environmental health problem affecting everyone in low-, middle-, and high-income countries as its source – combustion of fossil fuel – is ubiquitous. Household air pollution is mainly caused by the use of solid fuels (such as wood, crop wastes, charcoal, coal and dung) and kerosene in open fires and inefficient stoves. Most of these people are poor and live in low- and middle-income countries.
Exposure to smoke from cooking fires causes 3.2 million premature deaths each year, mostly in low- and middle-income countries, where polluting fuels and technologies are used every day, particularly at home for cooking, heating and lighting. Women and children, who tend to spend more time indoors, are affected the most. LMIC also suffer the greatest from exposure ambient air pollution with 3.68 million premature deaths each year, which is almost 8 times the mortality rates in high income countries (0.47 million).
The main pollutants are:
- particulate matter, a mix of solid and liquid droplets, with larger particles (PM10) arising from pollen, sea spray and wind-blown dust from erosion, agricultural spaces, roadways and mining operations, while finer particles (PM2.5) can be derived from primary sources (for example combustion of fuels in power generation facilities, industries or vehicles) and secondary sources (for example chemical reactions between gases)
- nitrogen dioxide (NO2), a gas from combustion of fuels in processes such as those used for furnaces, gas stoves, transportation, industry and power generation;
- sulfur dioxide, another gas mainly from the combustion of fossil fuels for domestic heating, industries and power generation; and
- ozone at ground level, caused by a chemical reaction of gases, such as NO2, in the presence of sunlight. The pollutant that is most commonly monitored by regulatory frameworks and for which a lot of evidence of adverse health impact is available is particulate matter followed by nitrogen dioxide.
How air pollution affects our body
Particles with a diameter of 10 microns or less (≤ PM10) can penetrate and lodge deep inside the lungs, causing irritation, inflammation and damaging the lining of the respiratory tract. Smaller, more health-damaging particles with a diameter of 2.5 microns or less (≤ PM2.5 – 60 of them make up the width of a human hair) can penetrate the lung barrier and enter the blood system, affecting all major organs of the body. These pollutants increase the risk of heart and respiratory diseases, as well as lung cancer and strokes.
Ozone is a major factor in causing asthma (or making it worse), and nitrogen dioxide and sulfur dioxide can also cause asthma, bronchial symptoms, lung inflammation and reduced lung function.
In 2021 WHO updated the Global Air Quality Guidelines, which recommend the maximum safe level for PM2.5 annual average concentration of 5 μg/m3 or less. The guidelines provide evidence of the damage air pollution inflicts on human health, at even lower concentrations than previously understood. The updated guidelines provide recommendations on air quality guideline levels as well as interim targets for six key air pollutants. They also offer qualitative statements on good practices for the management of certain types of particulate matter (PM), for example, black carbon/elemental carbon, ultrafine particles, and particles originating from sand and dust storms, for which there is insufficient quantitative evidence to derive AQG levels.
Air pollution has a disastrous effect on children; there were more than 5 million deaths of children under the age of 5 years. More than 27% of those deaths – 1.7 million – were attributable to environmental factors, with air pollution foremost among them. Globally, lower respiratory infections are the second leading cause of death for children under 5 years. Every year, 442 000 children (as of 2022) younger than 5 years die prematurely from breathing polluted air. Evidence suggests that air pollution could also harm children before they are born (reduced birth weight) through their mothers' exposure. There is emerging evidence linking air pollution exposure to cancer, neurodevelopmental and metabolic diseases in children.
As well as affecting our health, pollutants in the air are also causing long-term environmental damage by driving climate change, itself a major threat to health and well-being.
Already in 2018, the UN Intergovernmental Panel on Climate Change warned that coal-fired electricity must end by 2050 if we are to limit global warming rises to 1.5 °C. If not, we may see a major climate crisis in just 20 years.
Affordable strategies exist to reduce emissions from energy, transport, waste management, housing and industrial sectors. These interventions often carry other benefits like reduced traffic and noise, increased physical activity and better land use – all of which contribute to improving health and well-being. WHO also supports cities with the data, tools and capacity to select, implement and track clean and healthy policies at the city level. Better air quality will benefit all of us, everywhere.
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