Fine particulate matter, temperature, and lung function in healthy adults: findings from the HVNR study

Both ambient particulate air pollution and temperature alterations have been associated with adverse human health effects, but the interactive effect of ambient particulate and temperature on human health remains uncertain. The present study investigated the effects of ambient particulate matter with an aerodynamic diameter⩽2.5 μm (PM2.5) and temperature on human lung function simultaneously in a panel of 21 healthy university students from the Healthy Volunteer Natural Relocation (HVNR) study in the context of suburban/urban air pollution in Beijing, China. Each study subject used an electronic diary meter to record peak expiratory flow (PEF) and forced expiratory volume in 1s (FEV1) twice a day for 6 months in three periods before and after relocating from a suburban area to an urban area with changing ambient PM2.5 and temperature levels in Beijing. Hourly-averaged environmental data were obtained from central air-monitoring sites. Exposure effects were estimated using generalized linear mixed models controlling for potential confounders. Study subjects provided 6494 daily measurements on PEF and 6460 daily measurements on FEV1 over the study. PM2.5 was associated with reductions in evening PEF and morning/evening FEV1 whereas temperature was associated with reductions in morning PEF. The estimated PM2.5 effects on evening PEF and morning/evening FEV1 in the presence of high temperature were generally stronger than those in the presence of low temperature, and the estimated temperature effects on morning/evening PEF and morning FEV1 in the presence of high PM2.5 were also generally stronger than those in the presence of low PM2.5. For example, there were a 2.47% (95% confidence interval: -4.24, -0.69) reduction and a 0.78% (95% confidence interval: -1.59, 0.03) reduction in evening PEF associated with an interquartile range increase (78.7 μg/m(3)) in PM2.5 at 4-d moving average in the presence of high temperature (⩾21.6 °C) and low temperature (<21.6 °C), respectively. Our findings suggest that ambient particulate and temperature may interact synergistically to cause adverse respiratory health effects.