Are tumbleweeds of cat hair blowing through your halls? Is dust caked on your ceiling fan blades? And what about those bed sheets? Washed them lately?

Indoor allergens aren’t always so easy to spot, but a new study shows about half of U-S homes have higher levels of at least three of these sneeze inducers. And for asthma sufferers, indoor allergens are more than just annoying… they can trigger asthma attacks.

But scientists from the National Institute of Environmental Health Sciences and the University of Iowa found that keeping indoor allergens like dust mites and pet hair in check can help keep breathing trouble at bay.

Experts say understanding the role indoor allergens play in asthma is key because people spend more time inside than out.

More than twenty-two-million people in the United States have asthma. Allergens and common irritants such as smoke often trigger swelling in the airways, making it difficult for someone with asthma to breathe.

Some of the most common indoor allergens that affect asthma are pet dander, cockroaches and dust mites. Having dogs or cats not only spreads pet dander in a house but also increases the number of dust mites, which feed off dead skin cells. Aside from getting rid of pets altogether, experts say keeping pets out of your bedroom and vacuuming at least twice a week can diminish pet-related allergen levels in your home.

Regular cleaning also helps keep allergen levels down.

You know what that means… time to gun down those tumbleweeds.