The haze weather in B city is mainly caused by pollutants such as fine particles (PM2 5), nitrogen hydrocarbons and respirable particles (PM10)  Statistical research shows that the number of haze weather in B City last year was much lower than that of the previous year, and it was the largest decline since the relevant statistics were available
However, statistical surveys show that public concern and anxiety about the haze weather in City B has greatly increased in the past year
Last year, B City held a large-scale international conference, and temporary measures such as traffic restrictions and construction site stoppage were the main reasons for the decrease in haze weather