Scientists warn that on 4 September, Sunday, dangerously close to Earth will fly asteroid 2016 QA2. The dimensions of this space flying object – within 50 metres – considerably larger than the Chelyabinsk meteorite". Thus, if the collision happens, the troubles QA2-2016 (sometimes it is referred to and so) can do much more, and it's not only the broken glass.
The probability of collision, if you talk calmly and mathematically, is not so big, but it is. The problem here is more psychological, the probability increases significantly already in the minds of earthlings, given the risks posed by the clash.
Astronomers warn that at such a scale, even if the asteroid would disintegrate in the atmosphere and partly burn, on the Ground collision may create great trouble.
On the other hand, somehow, but in humans there is an understanding and awareness of the likelihood and the great danger of collision with such objects. Therefore, there is a warning system about such universal disasters. If so, 48 hours prior to the collision is calculated, at least roughly, the impact area of the asteroid, the optimists can say that it flies by. However, the danger exists and it should not be forgotten.
Source: http://universe-tss.su/main/klimat/41417-asteroid-mozhet-stolknutsya-s-zemley-4-sentyabrya.html