Air Quality Standards National Coverage for Criteria Pollutants Across the World

Air pollution is a major environmental health risk, contributing to millions of premature deaths each year. A primary tool for combating this crisis is the use of national air quality standards, limits on air pollution set by countries to protect their citizens. This report, based on a database (Link to Source) compiled by the World Health Organization (WHO) and the Swiss Tropical and Public Health Institute (Swiss TPH), provides an overview of the regulatory landscape.

This analysis counts, for each of the 251 countries and territories, how many of the six WHO-comparable criteria pollutants have national standards using WHO-aligned averaging times (1 year, 24 hours, 8 hours, 1 hour, 15 minutes, 10 minutes). Standards based on other averaging times are excluded from the WHO dataset, even if they exist nationally. For example, the U.S. regulates SO₂ with a 3-year average of the 99th percentile of 1-hour daily maximums, which is not captured here—so its total is 5 pollutants instead of 6. The analysis focuses on whether standards exist, not on their stringency.

For e.g. If India’s count is 6, it indicates that national standards exist for all six criteria pollutants, with averaging times aligned to WHO guidance. In this analysis, a country is considered to have a standard for a pollutant even if it specifies only a single averaging time (e.g., 24 hours); multiple averaging times are beneficial but not required for a country to qualify as having a standard for that pollutant.

Criteria Pollutants:

• Particulate Matter (PM2.5, PM10): Tiny particles from vehicles and industry that penetrate deep into the lungs and bloodstream, causing heart, lung, and neurological diseases. PM2.5 is especially harmful.
• Nitrogen Dioxide (NO2): A reddish-brown gas from vehicles and power plants; irritates airways, worsens asthma, and reduces lung function.
• Sulfur Dioxide (SO2): From burning coal and oil; causes acid rain and immediate breathing issues by constricting airways.
• Ozone (O3): At ground level, forms smog via sunlight-driven reactions; triggers asthma, chest pain, and reduced lung function.
• Carbon Monoxide (CO): Odorless gas from incomplete combustion; blocks oxygen in blood, leading to dizziness, confusion, or death.

The Findings

The analysis shows a clear global divide in air quality standards.

• 79 countries (31.5%) have national standards for all six WHO-comparable pollutants, reflecting a strong regulatory commitment.
• 114 countries and territories (45%), mostly in Africa, have not set a single standard—leaving large populations unprotected.
• 58 countries fall in between, with partial coverage. Some use methods not captured by the WHO dataset—for example, the U.S. regulates SO₂ using a 3-year average of the 99th percentile of daily 1-hour peaks, which is outside the WHO’s standard averaging times. Hence, the U.S. count here is 5 rather than 6.

WHO Guidelines vs. National Standards: A Deeper Look

WHO guidelines are science-based, advisory limits for pollutant concentrations below which health risks are minimal. They are not legally binding but serve as a benchmark for countries.

National standards, by contrast, are legally set limits shaped by health priorities, economics, and politics. Hence, they often diverge from WHO guidance—even under the same averaging times.

Example (annual average PM2.5):

• Norway & Israel: 5 µg/m³ (WHO-aligned)
• U.S.: 9 µg/m³
• India: 40 µg/m³
• Algeria: 80 µg/m³
• Similar variation exists for other pollutants.

Furthermore, enforcement differs widely:

• U.S.: NAAQS under the Clean Air Act; binding with federal oversight.
• EU: Binding Air Quality Directives; enforceable via European Court of Justice.
• China: Strict GB 3095 standards; officials face political consequences for non-compliance.
• India: NAAQS legally notified but weakly enforced; closer to guidelines in practice.
• Many LMICs: Legal on paper but function as guidelines due to weak capacity.

Takeaway: Setting a standard is just step one. Real impact depends on alignment with WHO levels and, above all, strength of enforcement.

Conclusion

This analysis shows a stark divide: 79 countries have adopted WHO-aligned air quality standards, while 114 have none—leaving billions without basic legal protection. Even where standards exist, they vary greatly in stringency and enforcement, from Norway and Israel’s strict limits to much weaker thresholds in India and Algeria.

Closing these gaps is critical, but governments and funders cannot act alone. Individuals bear a powerful responsibility too—by supporting clean air initiatives, raising awareness, and holding leaders accountable. Clean air is not a privilege; it is a human right, and securing it depends on the choices and actions we all take today.