Secondary pollution refers to the re-contamination of the environment after the pollutants are discharged from the pollution source into the environment, and new pollutants are generated under the action of physical, chemical or biological factors. which of the following are secondary pollutions? ['Harmful compounds in automobile exhaust, photochemical reactions under the action of sunlight, generate a variety of strong oxidants, mainly ozone, endanger human health.', 'During the decoration of the house, the construction machinery emits a strong noise, which seriously affects the rest and life of the surrounding residents.', 'Pesticides remain in cotton and hemp fibers. Although the residual amount is small after being made into clothing, frequent contact with the skin can also cause harm to the human body.', 'People smoked second-hand smoke in public places.']