Countries by PM2.5 air pollution, mean annual exposure (micrograms per cubic meter)

Ranking 2020

Analysis

This metric measures population-weighted exposure to fine particulate air pollution. The World Bank defines it as follows: population-weighted exposure to ambient PM2.5 pollution is defined as the average level of exposure of a nation's population to concentrations of suspended particles measuring less than 2.5 microns in aerodynamic diameter, which are capable of penetrating deep into the respiratory tract and causing severe health damage. Exposure is calculated by weighting mean annual concentrations of PM2.5 by population. The unit is micrograms per cubic meter, and a higher value indicates greater pollution exposure. This dataset covers all 200 countries included in the World Bank World Development Indicators under indicator code EN.ATM.PM25.MC.M3, with data from 2020. All 200 datapoints are classified as official quality, and all fall within the last seven years. The viability checks identified 21 extreme outliers using a three-standard-deviation threshold, and the data spans a range from 4.90 to 85.12, a spread of approximately 1,639 percent.

The top of the ranking is dominated by West African and Gulf states. Niger leads at 85.12 µg/m³ (rank 1), followed by Qatar at 75.66 (rank 2) and Mauritania at 70.82 (rank 3). Senegal (rank 4, 63.74), Bahrain (rank 5, 58.50), Burkina Faso (rank 6, 58.47), and Mali (rank 8, 56.78) all exceed 55 µg/m³. India ranks 19th at 48.39, making it the most populous country in the top 20. Pakistan (rank 25, 43.00) and Bangladesh (rank 26, 42.38) also appear in the upper quarter of the ranking. Gulf states including Kuwait (rank 12, 53.72), Saudi Arabia (rank 13, 53.15), and the United Arab Emirates (rank 33, 36.31) cluster in the upper tier alongside Sub-Saharan and South Asian nations.

The middle of the ranking includes several European and Latin American countries with values between roughly 10 and 25 µg/m³. Bosnia and Herzegovina ranks 61st at 26.60, and North Macedonia ranks 63rd at 26.12. South Africa appears at rank 81 with 23.75, while Chile ranks 85th at 23.28. Poland ranks 114th at 17.96 and Italy ranks 133rd at 14.66. The United States ranks 185th at 7.81, and Canada ranks 191st at 6.57. Among the lowest-ranked countries, Finland (rank 200, 4.90), Iceland (rank 199, 5.11), Sweden (rank 198, 5.64), and Norway (rank 196, 6.06) consistently record the smallest exposure values. The bottom fifth of the ranking is composed almost entirely of Northern European, Pacific island, and North American countries.

This metric captures population-weighted mean annual exposure rather than peak concentrations or localized hotspots, so it may understate pollution burdens in specific urban areas or industrial zones within otherwise lower-ranked countries. The data reflects modeled estimates weighted by population distribution, which means countries with large rural populations may show different values than urban-centric measurements would suggest. The 21 extreme statistical outliers identified in the data may reflect genuine geographic or climatic variation rather than reporting error, but users should interpret the most extreme values with caution. The metric does not capture indoor air pollution or occupational exposure. All 200 countries report from the same reference year of 2020, ensuring cross-country comparability, but year-specific conditions such as drought or unusual dust events could influence single-year figures.

Methodology

Data are drawn from the World Bank World Development Indicators, indicator code EN.ATM.PM25.MC.M3, for the reference year 2020. The metric is defined verbatim in the source as: population-weighted exposure to ambient PM2.5 pollution is defined as the average level of exposure of a nation's population to concentrations of suspended particles measuring less than 2.5 microns in aerodynamic diameter, which are capable of penetrating deep into the respiratory tract and causing severe health damage. Exposure is calculated by weighting mean annual concentrations of PM2.5 by population. The unit is micrograms per cubic meter. The dataset covers 200 countries, all of which have data from within the last seven years, and 100 percent of datapoints are classified as official quality. The ranking is ordered from highest to lowest exposure, so rank 1 (Niger, 85.12) represents the most polluted population-weighted environment and rank 200 (Finland, 4.90) represents the least. The full range spans 4.90 to 85.12 µg/m³, a spread of approximately 1,639 percent. Viability checks flagged 21 extreme outliers at the three-standard-deviation threshold. Average year-over-year change across the dataset is 6.2 percent, well within the 50 percent volatility threshold. The metric excludes indoor air pollution and does not capture sub-national or peak concentration variation.

Sources

• World Bank