Answer:
The air pollution in china decreases due to less usage of transportation and shutdown of industries.
Step-by-step explanation:
From December to march, transportation and industrial work is greatly affected due to the corona virus. Due to reduction of activities in both transportation and industries, there is a lot of decrease occurs in the air pollution. We know that smoke produce by vehicles and industries are the main cause of pollution so that's why air pollution decreases between December to march..