Presented By: Yisi Liu, University of Washington

Background: Modern mobility can include mixtures of transportation options, which potentially impact pollution exposures and health.
Objectives: To investigate variations in traffic-related air pollution (TRAP) exposures in different transportation modes and related cardiopulmonary health effects in Chengdu, China.
Methods: This was a randomized double-blind crossover intervention trial. Each of the twenty-one eligible subjects enrolled into the study completed eight two-hour trips on script route between November and December in 2019. Subjects travelled with each of the four modes (walking, bus, subway and car) twice, where they used effective masks once, and another one with sham masks. The order of the two masks was randomized and double-blind. Each trip was separated by at least one day. During the travelling, personal ultrafine particles (UFP), PM2.5, black carbon (BC) and noise levels were monitored using portable sensors. Blood pressure, fractional exhaled nitric oxide (FeNO) and spirometry were measured right before and after each trip.
Results: Mean age of the 21 subjects was 27.4 years; 15 were female and 6 were male. Walking exposed subjects to the highest median PM2.5 levels, while taking a bus had the highest average PM2.5, BC and UFP concentrations. During the transportation, per 1ug/m3 increase in BC, FeNO increased 2.0 ppb (95%CI: 0.2, 3.0). Increased PM2.5 concentrations and lung-deposited surface area of UFP were associated with decreased forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC). Compared to travelling with sham masks, people wearing effective masks had higher FEV1/FVC ratios (0.75%, 95% CI: 0.1% -- 1.4%).
Conclusion: Results from this study suggest that TRAP had adverse effects on respiratory health among healthy young adults. The Intervention of using face masks could prevent the adverse effects of TRAP on respiratory system.

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