Traveling abroad to cities with some of the highest air pollution levels on the planet was associated with decreased lung function among otherwise healthy college students based in and around New York City, researchers reported.
In the first study to examine the respiratory impact of short-term travel to high pollution areas, exposure to indoor particulate mater (PM2.5) in cities with very high pollution levels was associated with acute changes in pulmonary function, as measured by forced expiratory volume (FEV1).
Similar results were seen between outdoor particulate matter monitor concentrations and lung function reductions.
“We show, for the first time, that exposure to increased levels of indoor particulate matter, in cities abroad is associated with statistically significant acute changes in pulmonary function in healthy young adults,” wrote Terry Gordon, PhD, of New York University School of Medicine, and colleagues.
In an interview with MedPage Today, Gordon said the finding of acute lung function decline in healthy young people associated with travel to areas with very high air pollution levels highlights the even higher potential risk to people with elevated cardiovascular or pulmonary risk.
“To me, it is obvious that someone with impaired cardio- or pulmonary health should be aware that when they go to cities in India, for example, or China, with high pollution levels, their health could be adversely affected,” he said.
“There are over a billion international travelers a year and that figure is projected to reach 1.8 billion in the next 10- to 15 years. That is a lot of international travel. This potential risk needs to be on the radar of physicians and their patients.”
Gordon noted that more and more travelers from the U.S. are now visiting areas where air pollution levels are among the highest on earth, including large cities in Asia and Africa.
The final study population included 34 non-smoking, young adults attending colleges in New York City and traveling abroad for academic reasons for at least a week. The participants traveled to either Europe, South Asia, East Asia, or Africa, and the cities visited were categorized as low pollution (PM2.5 concentrations of 0 to 35 μg/m3), medium (36-100 μg/m3), or high (>100 μg/m3).
The study participants were trained to measure and record their lung function and indoor PM exposure levels using a provided portable spirometer and a portable, low-cost PM2.5 sensor (Airbeam HabitatMap, NYC).
Measurements were obtained in the morning and at night daily during the week before travel, the first week after arrival during their stay abroad, and for 1 week after returning home. Each of the participants provided at least 5 days of monitoring during each measuring period.
The researchers used a mixed effects statistical model to study the association between FEV1 and PM2.5 exposure concentrations.
“In some regions, mean indoor PM2.5 concentrations in cities abroad were significantly higher than pre-travel New York concentrations, particularly in cities in South and East Asia. Cities in East Asia, as a group, had the highest (mean ± SD) indoor PM2.5 measurements (73 ± 96 μg/m3 and 95 ± 114 μg/m3 for morning and evening measurements, respectively),” the researchers wrote.
The mixed-effects analysis revealed that travel to a “high” polluted city was associated with a statistically significant mean decrement of 235 ml (95% CI, -365, -112ml) in evening FEV1.
“When further analyzed using the maximum percentage change of FEV1, where maximum change = (minimum FEV1 abroad – mean pre-travel FEV1 /mean FEV1 in pre-travel NY), travel to a highly polluted city was associated with a 6.5% reduction in evening FEV1 compared with the overall population mean,” Gordon and colleagues wrote.
Gordon said a destination’s air quality is not something most people give much thought to before they travel.
The environmental researcher said that even though he has studied the impact of air pollution exposure on health for many years, he too, along with his colleagues, failed to consider the potential risk when they traveled to a conference on air pollution held in Delhi, India.
The conference was held in November, which is a month with notoriously high PM2.5 concentrations in the city of close to 20 million people. “All nine of us started feeling ill,” he said. “One person went to the hospital and another should have. And only one of us was smart enough to bring a (PM2.5 filtering) mask. We just didn’t think about it.”
Funding for the study was provided by the National Institute of Environmental Health Sciences Core Center and the Air and Waste Management Association.