Although human population studies have linked air pollution to chronic inflammation of nasal and sinus tissues, direct biological and molecular evidence for cause and effect has been scant. Now, Johns Hopkins researchers report that experiments in mice continually exposed to dirty air have revealed that direct biological effect.
New findings have broad implications for the health
Researchers have long known that smog, ash and other particulates from industrial smokestacks and other sources that pollute air quality exacerbate and raise rates of asthma symptoms, but had little evidence of similar damage from those pollutants to the upper respiratory system. The new findings, published in the American Journal of Respiratory Cell and Molecular Biology, have broad implications for the health and wellbeing of people who live in large cities and industrial areas with polluted air, particularly in the developing world.
In India people are at higher risk of developing chronic sinus problems
“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.
Researchers exposed 38 eight-week-old male mice
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.
Researchers saw many more white blood cells that signal inflammation
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.