Cockroaches are more than just unpleasant house guests — they could be affecting the air we breathe.
A new study from North Carolina State University has found that homes with more cockroaches also have higher levels of allergens and bacterial toxins known as endotoxins.
The good news is that when pest control successfully eliminates cockroaches, these harmful substances drop sharply, improving overall indoor air quality.
Endotoxins are small pieces of bacterial cell walls that are released when bacteria die. They can cause allergic reactions and inflammation when inhaled. Because cockroaches eat almost anything — from leftover food to garbage — they carry many types of bacteria in their gut.
As they move around, they shed droppings full of endotoxins and allergens into the environment. While humans and pets also produce small amounts of endotoxins, the researchers found that most of the endotoxins in infeste…
“Endotoxins are important to human health because breathing them in can trigger allergic reactions,” said Dr. Coby Schal, the Blanton J. Whitmire Distinguished Professor of Entomology at NC State and one of the lead authors of the study.
“Earlier studies in U.S. homes found that endotoxin levels are much higher where cockroaches are present. The problem tends to be worse in low-income and multi-family housing, where infestations are more common.”
The research team conducted their study in multi-unit apartment buildings in Raleigh, North Carolina. They measured both the number of cockroaches and the amount of allergens and endotoxins in each apartment. Before starting any pest control treatment, they collected samples of both airborne and settled dust to establish a baseline.
The results showed a clear link between infestation levels and air contamination. Apartments with heavy infestations had much higher amounts of endotoxins, and interestingly, female cockroaches produced about twice as much endotoxin as males.
“Female cockroaches eat more than males, so their droppings contain higher amounts of endotoxin,” explained Madhavi Kakumanu, an NC State research scholar and co-author of the study. Kitchens had the highest readings, since they provide easy access to food sources for cockroaches.
To test whether pest control could improve indoor air quality, researchers divided the infested apartments into two groups: one received professional extermination, and the other did not. They also included a third group of apartments that had no infestations as a control. Dust and insect samples were collected again after three and six months.
The results were dramatic. Apartments that were successfully cleared of cockroaches showed a sharp drop in both allergen and endotoxin levels. In contrast, untreated apartments stayed contaminated.
“When you eliminate cockroaches, you eliminate their allergens,” said Schal. “Just reducing the number of cockroaches isn’t enough — even a few remaining insects can keep producing large amounts of allergens. Complete elimination is what makes the real difference.”
Kakumanu added that the study also found evidence that both allergens and endotoxins can become airborne, meaning that residents can inhale them without realizing it. This could help explain why cockroach infestations are strongly linked to asthma and other respiratory issues, especially in children.
The researchers now plan to study how cockroach allergens and endotoxins might work together to worsen asthma symptoms. “We suspect that asthma can become more severe because of the combined effects of these two substances,” Schal said. “Our next step is to test this idea in animal models.”
The study was published in *The Journal of Allergy and Clinical Immunology: Global* and involved collaboration between scientists at NC State, the University of Kentucky, and the University of Toronto.
This research provides powerful evidence that controlling cockroach infestations is not just about getting rid of pests — it’s about improving public health.
By reducing the allergens and bacterial toxins in homes, pest control can make a meaningful difference in breathing quality, especially in high-risk communities. For families struggling with asthma or allergies, a clean, pest-free home could literally be a breath of fresh air.
If you care about lung health, please read studies about marijuana’s effects on lung health, and why some non-smokers get lung disease and some heavy smokers do not.
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The study is published in Journal of Allergy and Clinical Immunology: Global.
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