This data is scraped from the municipality web page 93.123.36.139. As no API currently exists, it's parsing the charts and calculating the rates with 0.1% precision. The [sofia_airpollution_week.csv] dataset is updated every hour with the latest information. The full dump [sofia_airpollution.csv] is updated every Sunday morning. 

Each entry in the list of pollutants is followed by a marker if the value is valid. An invalid measurement may be caused by a faulty sensor or disturbance in the immediate vicinity of the station. 

The [stations.csv] file lists the types and location of each station. Names are in cyrillic. It will be updated when more stations are added. It is also possible that some are removed. 

The data is provided as is under CC0 and there is not guarantee for uptime. Quality of the data depends solely on what the Environment agency publishes plus the above mentioned margin of error. Attribution would be appreciated.

Questions at Twitter: @yurukov and yurukov@gmail.com