The Visibility app is an experimental Android app that gauges just how polluted the air outside is. By simply taking a picture and uploading it to the app's database, you can know if the air outside is safe to breathe or not.
The Visibility app is currently an experimental one, and it's free to download. The more people who download and upload the Visibility app, the quicker the developers and the users will know if the information on air quality that it is giving is legitimate or not. Click the links to learn more.