10月31日午後、微小粒子状物質「PM2.5」が、大気汚染が深刻な中国から日本の広範囲にわたって飛来する可能性が出てきた。九州大学応用力学研究所によると、PM2.5を含む微粒子は、31日午後に近畿から関東全域へ広がると予測されている。
PM2.5は大気中に浮遊している2.5μm（1μmは1mmの千分の1）以下の小さな粒子で髪の毛の太さの1/30程度と非常に小さい。そのため、肺の奥深くまで入りやすく、ぜんそくなどを引き起こす危険性があるとされており、研究が行われている。世界保健機関（WHO）の専門機関は今月17日、PM2.5などの大気汚染物質による発がんリスクを最高レベルに分類したと発表。国際社会が早急に対策をとるように求めている。
日本気象協会は、飛来は明日・明後日も続く見込みと報じており、外出などの際は、マスクやメガネなどで鼻や目をガードするなどの対策を考えたほうが良さそうだと、注意を促している。
PM2.5の飛来はあす・あさってと続く
PM2.5は広範囲に飛んでくる予測となっています。対策として、マスクやメガネなどで鼻や目をガードすることを心がけてもよさそうです。PM2.5の飛来しやすい状況はあす・あさってと続く見込みです。
（tenki.jp「PM2.5が広範囲に飛来か」より。2013/10/31 07:56）
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