In recent years, smog weather has occurred frequently, seriously endangering people's health. The following measures are ineffective in preventing smog weather: (1) Sprinkle water on the construction

In recent years, smog weather has occurred frequently, seriously endangering people's health. The following measures are ineffective in preventing smog weather: (1) Sprinkle water on the construction site regularly. A. Sprinkle water regularly on the construction site to reduce dust and effectively prevent haze weather;

B, automobile exhaust contains smoke and dust produced by insufficient fuel combustion, which will produce particles with a diameter of less than or equal to 2.5 microns, so it can cause the increase of PM2.5 in the atmosphere and produce haze weather, so it cannot prevent haze;

C. Reducing the combustion of fossil fuels will reduce harmful gases such as CO, SO2 and dust, thus reducing PM2.5 in the atmosphere, so it can prevent smog;

D. Banning burning straw will reduce the emission of air pollutants, so it can prevent smog.

So choose B.