Nine-year-old Kathryn Chenaille spent three months living at the Ronald McDonald House in Baltimore after a bone marrow transplant made necessary by her battle with aplastic anemia.

Her immune system was nearly wiped out by the procedure so her family worried about the air she would be breathing in the communal residence. Her father went out and bought for her room a high-powered air purifier that uses a UV filter to kill germs. The family thinks the filter kept Kathryn from getting sick while she was at Ronald McDonald. Now that she is in remission, Kathryn wanted to give something back to the place she left in February -- air purifiers.

Any day now, the Baltimore facility will get 37 purifiers, a gift from a company that makes the Secure Air 1200. When they heard Kathryn's story -- and her goal to bring clean air to other sick kids -- they donated the first batch. Now, Kathryn and her family are trying to raise money to buy air purifiers for Ronald McDonald Houses across the country. With every $45 raised, another room at a Ronald McDonald House will get an air purifier.

"If we could do it all across the country, that'd be great, but that's pretty big so we'll start with Pennsylvania," said Kathryn's mother Carolyn.