The percentage of population exposed to levels exceeding UN World Health Organization (WHO) guidelines of PM2.5 are derived from estimates of annual concentrations of very fine particulates produced by the Global Burden of Disease (GBD) study, an international scientific effort led by the Institute for Health Metrics and Evaluation at the University of Washington. The percentage of population exposed to ambient concentrations of PM2.5 that exceed the WHO guideline value is defined as the portion of a country’s population living in places where mean annual concentrations of PM2.5 are greater than 10 micrograms per m³, the guideline value recommended by the World Health Organization as the lower end of the range of concentrations over which adverse health effects due to PM2.5 exposure have been observed. Estimates of annual concentrations are generated by combining data from atmospheric chemistry transport models, satellite observations of aerosols in the atmosphere, and ground-level monitoring of particulates. Overlaying PM2.5 estimates with gridded population data, the percent of a nation's people that lives in areas where PM2.5 concentrations exceed recommended levels is calculated by summing the population for grid cells where PM2.5 concentrations are beyond a threshold value, in this case 10 micrograms per m², and then dividing by total population. These data were collected globally at the country level from 1990, 1995, 2000, 2005, and 2010-2015. Resource Watch shows only a subset of the data set. For access to the full data set and additional information, see the Learn More link.
PM2.5 air pollution, population exposed to levels exceeding WHO guideline value (% of total)
Pollutant concentrations are sensitive to local conditions, and even monitoring sites in the same city may register different levels. Direct monitoring of PM2.5 is still rare in most parts of the world, and measurement protocols and standards are not the same for all countries. These data should be considered as only a general indication of air quality, intended to inform cross-country comparisons of the health risks due to particulate matter pollution. The guideline set by the World Health Organization (WHO) for PM2.5 is that annual mean concentrations should not exceed 10 micrograms per m², representing the lower range over which adverse health effects have been observed. The WHO has also recommended guideline values for emissions of PM2.5 from burning fuels in households.
(1) Brauer, M. et al. 2016, for the Global Burden of Disease Study 2015. Accessed through Resource Watch, (date). www.resourcewatch.org.
(2) World Bank Group. 2015. "PM2.5 Air Pollution, Population Exposed to Levels Exceeding WHO Guideline Value (% of Total)." http://data.worldbank.org/indicator/EN.ATM.PM25.MC.ZS. Accessed through Resource Watch, (date). www.resourcewatch.org.
1990, 1995, 2000, 2005, 2010-2015
Annual (varies based on survey coverage)