WHO Air Quality Guideline
Guideline set by the World Health Organization for exposure to fine particle (PM2.5), based on evidence of the health effects of long-term exposure to PM2.5. The guideline is set at an annual average PM2.5 concentration of 10 µg/m3 (based on data averaged over one year).
WHO Interim Targets
Three interim air quality targets (IT) set by the World Health Organization for annual average fine particle (PM2.5) concentrations (based on data averaged over one year): IT-1 ≤ 35 µg/m3; IT-2 ≤ 25 µg/m3; and IT-3 ≤ 15 µg/m3.
Groupings of countries used by the World Health Organization: African region (AFRO), European region (EURO), Region of the Americas (PAHO), South-East Asia Region (SEARO), Western Pacific Region (WPRO), and Eastern Mediterranean Region (EMRO).
Groupings of countries used by the World Bank: South Asia, East Asia and Pacific, Europe and Central Asia, Latin America and Caribbean, Middle East and North Africa, Sub-Saharan Africa. See World Bank.