Below is information on the current background air quality in some of Europe's major cities based on data taken from http://www.airqualitynow.eu and recorded at 7:55 am GMT May 14.  City Quality Amsterdam  Very good [21] Berlin  Very good [18] Brussels  N/A Krakow  Moderate [51] Oslo  Very good [16] Prague  Very good [16] London  Very good [20] Madrid  Good [38] Paris  Good [27] Stockholm  Good [25] Zurich  Very good [20] Legend

Below is information on the current background air quality in some of North America's major cities based on data taken from http://www.airnow.gov recorded at 13:00 pm GMT on May 13. 

Below is information on the current background air quality in some of Europe's major cities based on data taken from http://www.airqualitynow.eu and recorded at 8:25 am GMT May 13.  City Quality Amsterdam  Very good [19] Berlin  Good [25] Brussels  N/A Krakow  Very good [16] Oslo  Good [29] Prague  Very good [18] London  Very good [11] Madrid  Good [43] Paris  Very good [23] Stockholm  Good [33] Zurich  Very good [21] Legend

Below is information on the current background air quality in some of North America's major cities based on data taken from http://www.airnow.gov recorded at 13:10 pm GMT on May 10.