Annual increases in global travel have resulted in more individuals being exposed to varying environmental conditions abroad and, thereby, subject to air pollution related health risks. Individuals who travel abroad may be exposed to varying levels of air pollution within a matter of hours. We wish to consider whether exposure to air pollution could be a significant contributor to the risk of illness and death in travelers, particularly those who travel to highly polluted cities. We report the findings of a study in which the peak expiratory flow (PEF) of a traveler decreased in Shanghai relative to baseline in New York City; the decline in PEF correlated to concentration of particulate matter (PM2.5). We discuss the health implication of these results on global travel.