Air Quality Index
This plug-in gets the air quality information from http://aqicn.org. Through your IP address the next nearby sensor station will be discovered.
If you encounter that a value stays to zero, it means the sensor station doesn't support that value.
Besides the air pollution level the plug-in also states a cautionary statement. Both states can be used to let nymea notify you about the pollution level and inform you what precautions should be taken.
More about the different Air Quality Levels: https://www.airnow.gov/index.cfm?action=aqibasics.aqi