Air Pollution May Directly Cause Year-Round Runny Noses, According to a Mouse Study

Sinuses of mice that inhaled polluted air. The sinus surface is breached as seen by the reduction in proteins that hold the cells together, such as E-cadherin (red).

Credit: Ramanathan lab

The new findings, published in the American Journal of Respiratory Cell and Molecular Biology, have broad implications for the health and well-being of people who live in large cities and industrial areas with polluted air, particularly in the developing world.

“In the U.S., regulations have kept a lot of air pollution in check, but in places like New Delhi, Cairo or Beijing, where people heat their houses with wood-burning stoves, and factories release pollutants into the air, our study suggests people are at higher risk of developing chronic sinus problems,” says Murray Ramanathan, M.D., associate professor of otolaryngology – head and neck surgery at the Johns Hopkins University School of Medicine.

According to the Centers for Disease Control and Prevention, more than 29 million people in the U.S. or more than 12 percent of adults have a chronic sinusitis diagnosis. Chronic sinusitis can cause congestion, pain and pressure in the face, and a stuffy, drippy nose.

Numerous studies have reported significant social implications of chronic sinonasal disease, including depression, lost productivity and chronic fatigue.

To see how pollution may directly affect the biology of the upper airways, the researchers exposed 38 eight-week-old male mice to either filtered air or concentrated Baltimore air with particles measuring 2.5 micrometers or less, which excludes most allergens, like dust and pollen. The aerosolized particles, although concentrated, were 30 to 60 percent lower than the average concentrations of particles of a similar size in cities like New Delhi, Cairo and Beijing.

Nineteen mice breathed in filtered air, and 19 breathed polluted air for 6 hours per day, 5 days a week for 16 weeks.

The researchers used water to flush out the noses and sinuses of the mice, and then looked at the inflammatory and other cells in the flushed-out fluid under a microscope.

They saw many more white blood cells that signal inflammation, including macrophages, neutrophils and eosinophils, in the mice that breathed in the polluted air compared with those that breathed in filtered air. For example, the mice that breathed in the polluted air had almost four times as many macrophages than mice that breathed filtered air.