Pertubuhan Sains & Kesejahteraan
Science & Wellness Organisation
(PPM-013-05-16022012)
Special Consultative Status with the United Nations Economic and Social Council
Global Air Pollution Exposure
A WHO-Based Assessment of Air Pollution and Health Risk
Clean air is something most people assume they have. Yet across every region of the world, national air quality standards for fine particulate matter, nitrogen dioxide, sulfur dioxide, and carbon monoxide sit above the World Health Organization’s Air Quality Guidelines (AQGs), the internationally recognized, health-based benchmark for air quality.
This analysis is based on the World Health Organization’s Air Quality Guidelines (AQGs) as its reference point, as they represent the most robust health-based benchmark for air quality, developed through systematic scientific review of the evidence linking air pollution to disease. The data presented here draw on the WHO Air Quality Standards Database (Version 2.1, 2025 update), compiled in collaboration with the Swiss Tropical and Public Health Institute. The objective of this analysis is to raise public awareness of the scale of global exposure to air pollution, enabling individuals, communities, and organisations to better understand and respond to this public health challenge.
4
Major pollutants examined
100+
Countries reflected across the data
100%
Of countries shown exceed the WHO guideline
Fine Particulate Matter (PM2.5)
PM2.5 refers to airborne particles with a diameter of less than 2.5 micrometres, small enough to penetrate deep into the lungs and enter the bloodstream. It is one of the most extensively studied air pollutants due to its strong association with cardiovascular and respiratory disease, and is considered among the most harmful pollutants to long-term health. The World Health Organization Air Quality Guideline (AQG) for annual exposure is 5 μg/m³.
Annual average PM2.5 concentrations in all countries shown exceed the World Health Organization Air Quality Guideline (AQG) of 5 μg/m³, indicating widespread exposure to elevated levels of fine particulate matter. The exposure gap is global in scale. In North America, national standards are approximately twice the WHO guideline, while in parts of Asia they reach seven to eight times higher. In all cases, this indicates that populations may be exposed to PM2.5 concentrations associated with increased health risk, even where air quality is considered compliant with national standards. Fine particulate matter therefore represents a global public health concern, not one confined to any single region.
Nitrogen Dioxide (NO₂)
NO₂ is primarily produced by vehicle engines, power plants, and other combustion sources, making it especially prevalent in densely populated urban areas. Long-term exposure is associated with reduced lung function and increased susceptibility to respiratory infections, particularly among children. The World Health Organization Air Quality Guideline (AQG) for annual exposure is 10 μg/m³.
Annual average NO₂ concentrations in all countries shown exceed the WHO Air Quality Guideline (AQG) of 10 μg/m³, indicating persistent exposure to elevated levels of nitrogen dioxide. The exposure gap is particularly pronounced across the Americas, where national standards are frequently up to ten times higher than the WHO guideline, and in parts of Southeast Asia, where they reach nearly 30 times higher. This disparity indicates a substantial difference between national regulatory limits and health-based guideline levels, allowing exposure to concentrations associated with long-term respiratory impacts to remain within compliance frameworks.
Sulfur Dioxide (SO₂)
SO₂ is released mainly from the burning of fossil fuels containing sulfur, including coal-fired power generation and industrial processes. Short-term exposure can cause airway constriction and exacerbate asthma, particularly among children and older adults. The World Health Organization Air Quality Guideline (AQG) for 24-hour exposure is 40 μg/m³.
24-hour average SO2 concentrations in all countries shown exceed the WHO Air Quality Guideline (AQG) of 40 μg/m³, highlighting widespread exposure to unhealthy levels of sulfur dioxide. The gap is most extreme across parts of the Middle East and Southeast Asia, where national standards are nine to ten times higher than the WHO Air Quality Guideline (AQG). This indicates that short-term spikes in sulfur dioxide concentrations above WHO-recommended levels may occur without being classified as exceedances under national regulatory frameworks.
Carbon Monoxide (CO)
CO is a colorless, odorless gas produced by incomplete combustion, most commonly from vehicle exhaust. At elevated concentrations, it interferes with the blood's ability to carry oxygen, posing increased risk to individuals with cardiovascular conditions. The World Health Organization Air Quality Guideline (AQG) for 24-hour exposure is 4 mg/m³ (4,000 μg/m³).
24-hour average CO concentrations in all countries shown exceed the WHO Air Quality Guideline (AQG) of 4 mg/m³, highlighting widespread exposure to unhealthy levels of carbon monoxide. In the most affected locations, national standards are nearly three times higher than the WHO guideline, allowing concentrations associated with increased cardiovascular risk to occur within regulatory limits for prolonged periods.
Why Awareness Matters
The pattern across all four pollutants is consistent and global: in country after country, the air people breathe contains pollutant concentrations above the World Health Organization Air Quality Guidelines (AQGs). This is not a localized issue affecting a limited number of regions; it spans continents, income levels, and climates. Fine particulate matter, nitrogen dioxide, sulfur dioxide, and carbon monoxide together represent a global public health challenge affecting billions of people, often without their awareness.
This is the rationale for the Global Clean Air Campaign: to support public health by making exposure more visible. Large populations are exposed to air pollution associated with increased risks of cardiovascular disease, stroke, respiratory illness, and premature mortality, often without clear awareness of these risks due to the invisible and odourless nature of many pollutants, and their limited presence in everyday public discourse. Awareness is a foundational step in public health protection, enabling individuals and communities to better understand and respond to environmental health risks.
Using the World Health Organization Air Quality Guidelines, the most robust, health-based reference framework available, air pollution is presented as a measurable and understandable public health issue. The objective is to improve understanding of the scale of global exposure, supporting more informed decision-making and public health responses.
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Air pollution is one of the leading environmental risk factors for disease and premature mortality globally, yet it remains under-recognised in public awareness.
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Understanding exposure patterns supports individuals, families, and communities in making informed health-protective decisions.
Public awareness is essential for translating scientific evidence into action, including stronger public health advocacy and support for cleaner air policies.
Get Involved
The Global Clean Air Campaign is established to raise awareness of air pollution exposure and support collective action to protect public health and prevent disease. Together, this effort aims to strengthen awareness and create meaningful impact within communities worldwide.
Contribute to cleaner air and healthier communities by participating as a volunteer.