This is a geographical supplement: there are 6 foggy days in 65438+February. The horizontal axis of the statistical chart of material 2 is 1, 2, 3, 4, 5 from left to right.

(1) temperate monsoon climate, hot and rainy in summer and cold and dry in winter.

(2) Winter and spring are more than summer and autumn.

(3) Dust brought by winter wind; Waste from automobile exhaust; Burning coal in winter releases dust; Industrial waste gas; Dust pollution in construction sites, etc.