The crossword solutions for the term REDDEN AND CRACK are CHAP, which stands for Controlled Hazardous Air Pollutant. CHAPs are pollutants that are released into the air and can cause harm to human health and the environment. These pollutants are regulated by the Environmental Protection Agency (EPA) in the United States. CHAPs include chemicals such as lead, mercury, and arsenic, as well as particulate matter such as dust and smoke.