The document discusses the harms and unnecessity of duct cleaning services. It claims that duct cleanings are a scam and can actually make asthma and indoor air quality worse. Preventative measures like regularly changing furnace filters and having the AC coil checked are better alternatives. The EPA and studies have found uncertainty around the benefits of duct cleaning in most cases. Companies that offer duct cleaning services prey on consumers and the document advises readers to leave their ducts alone and not fall for deceptive "before and after" photos used in marketing.