During the 15 days from New Year's Eve to Lantern Festival , Beijing was affected  by haze  .Do you know what the haze is ? Today I will introduce it to you . Haze is air pollution  in which is mixed up with dust, smoke and other dry particles (,),and it covers  our blue sky ,so we can't see sunny days. It often happens in winter and spring. The haze brings much trouble  to people's lives. On the road many traffic accidents  happened because people can not see clearly. The haze is _ to our health. People also have to go to see the doctor because of the poisonous  air caused by the haze. As students, we must tell our friends and family members to go to work or school with the public traffic, such as the bus and the underground and BRT .Also we should plant more trees and develop green and energy to reduce  the haze. According to me, I will go to school by bike or on foot, and I won't throw the waste  anywhere . It may take about 20 years to solve the problems caused by the haze .I believe the environment will get better and better and haze weather will vanish completely with the help of new technology. When does it often happen ?
Summer and autumn Winter and summer Winter and spring All year round