I know most of you don't care about air polution bc you just never need to worry about it. But I m Chinese and live in north China (Tianjin University) with my children.There are only 3-4 days in a year that the PM2.5 is below 20. For the 80% days in a year,the PM2.5 is higher than 100 while the AV in US,CA,AUS,EU are around 20-25 μg/m³. PM2.5 can be a kind of fatal particle to destory your breathing system,especially the lung. The breathing system can not block PM2.5 particle because it's too tiny. Once the partical enter your lung,it'll never leave,and impossible to be discomposed/transformed as well. I don't know what to do,so can't help posting today's local PM2.5 and air quality index figures: PM2.5: Average number:381μg/m³, but from 160 to 470 μg/m³ in different area in the city of Tianjin. PM10: From 188-607μg/m³,no average number available. Air quality index:384 Lever: DANGEROUS Would you mind post yours local Index below.