Indoor air pollution often makes the air inside homes more unhealthy to breathe than air outdoors. The Environmental Protection Agency estimates that indoor air can be two- to five-times more polluted than the air outdoors. And while the EPA is responsible for cracking down on outdoor pollution -- the smog, ozone and other chemicals that spew from tailpipes and smokestacks -- protecting the air indoors is largely the responsibility of homeowners. Read the original article.