Children exposed to pets and pests have a lower risk of developing asthma.
Researchers at the National Institute of Health followed more than 400 children living in poor neighborhoods, who had at least one parent with asthma, or allergies.
Kids in homes with the most cockroach, mouse and cat allergens were the least likely to have asthma by the age of seven.
The study also found exposure to certain bacteria in house dust seemed to protect children from wheezing.
