CINCINNATI, Dec. 2 (UPI) -- Combined exposure to traffic outside and dust indoors may greatly increase the harm to children's lungs, U.S. researchers said.
Researchers at the University of Cincinnati said exposure to high levels of air pollution from traffic and of indoor dust -- in particular endotoxin released by bacteria found in dust -- caused 36 percent of the children to demonstrate persistent wheezing at age 3.
Endotoxin, a component of bacteria thought to trigger an immune response in humans, was measured from dust samples collected prior to age 1. Only 11 percent of children exposed to low levels of both traffic and dust experienced wheezing. Wheezing at age 3, is an early warning sign of asthma and other pulmonary conditions.
Eighteen percent of children exposed to low levels of indoor endotoxin and high levels of traffic-related particles experienced persistent wheezing. Endotoxin exposure alone appeared to have little effect.
"There is a clear synergistic effect from co-exposure to traffic-related particles and endotoxin above and beyond what you would see with a single exposure that can be connected to persistent wheezing by age 3," lead author Patrick Ryan said in a statement.