On March 31, the National Health and Family Planning Commission announced: “Shanghai and Anhui Provinces have found three cases of human infection with H7N9 bird flu. Two patients in Shanghai have died and one patient in Anhui is in serious condition”. When the news came out, the whole country shook.

As the number of cases continues to increase, some citizens talk about the "avian" discoloration. As a result, after the PM2.5, protective masks rekindled the explosion.

Dust masks are usually used to block dust or exhaust gas and cannot filter out germs. To cope with the flu, we should choose to use a surgical mask because the mask has a filter in the middle that can block particles of 5 microns (one millionth of a micrometer) or more.