A free app for Android, by insdio.

The widget shows the real-time AQI for more than 60 countries worldwide, with the data sources varying depending on the city. For example, the US Embassy PM2.5 data is used for Shanghai, Beijing, Chengdu, and Guangzhou, while the China Ministry Environment Pollution Department PM10 data is used for all other cities in China.

To install the widget, Android 4.0 (Ice Cream Sandwich) users should select the “All Apps” icon, then the widget tab, and click on the “Air Quality” widget. For other versions below 4.0, users should long-press in an empty area on the default home screen, select “Widgets”, and then “Air Quality”. The overall AQI, PM2.5, and PM10 measurements are updated every hour.