C40 Cities Air quality data explorer

The C40 Cities data explorer compares to the World Health Organization’s (WHO) health-based Air Quality Guideline (AQG) and/or its interim targets, and to that of other cities. The explorer uses data on ambient levels of fine particulate matter (PM2.5). The WHO AQG stipulates that annual average PM2.5 should not exceed 5 μg/m3. Interim targets are recommended as near-term goals for cities a long way from meeting the AQG.