When will underwear dry outside?

It is not suitable to hang clothes outside at night. Pollutants (usually in the air) usually spread as the sun rises in the morning. Before 9 o'clock in the morning, pollutants are concentrated near the ground. In order to prevent pollutants from entering clothes, clothes had better be dried after 9 am. After 6 pm, the sun began to weaken and pollutants began to concentrate near the ground, so you should put away your clothes before 6 pm, so don't take them out in the sun at night, because they can't be exposed to the sun and can't play a bactericidal role.