Saying “It’s not a problem” may seem to make life easier because if something is not a problem we can ignore it. That would be fine if it were true that “What you don’t know can’t hurt you.”

For a long time smoke from fires and engine exhaust was not considered a problem, so nothing was done to reduce the chemical emissions. Once people came to realize that the smog was hurting our health through asthma and other diseases, they started finding ways to improve the situation.