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 8:50 am GMT May 28.  City Quality Amsterdam  Good [28] Berlin  Very good [20] Brussels  N/A Krakow  N/A Oslo  Very good [24] Prague  Very good [18] London  Very good [24] Madrid  Good [27] Paris  Good [30] Stockholm  Good [37] Zurich  Good [35] Legend

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 9:00 am GMT May 27.  City Quality Amsterdam  Very good [23] Berlin  Very good [14] Brussels  N/A Krakow  N/A Oslo  Good [25] Prague  Very good [16] London  Good [36] Madrid  Good [32] Paris  Good [52] Stockholm  Good [44] Zurich  Good [25] Legend

SEOUL, May 27 (Yonhap) -- The Seoul Metropolitan Government said Monday it will equip heavy vehicles with dust reduction devices and introduce a warning system against ultrafine particles as part of efforts to clean up the air and promote public health. As nano-sized matter, smaller than 2.5 micrometers, ultrafine particles originate from different natural and man-made sources such as fires and diesel exhaust. As the particulate matter penetrates deep within the lungs, it is believed to cause adverse health effects such as respiratory problems and cardiovascular disorders.

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 1:00 pm GMT on May 24.