Actually I’ve uploaded this plasmoid to kde-apps since about two months ago. The applet does support English and Simplified Chinese. However, the api returns only Chinese strings, which makes this applet looks like Chinese-only.
Thanks for PM25.in’s free API. Now you can check the city’s air quality index (AQI) in mainland China, just in your favourite desktop environment.
The applet is totally open-source and free for everyone. You can check the source code on Git@OSC.