Particulate matter, metal components, and lung function in a highly exposed population

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Background: Exposure to ambient particulate matter (PM) has been associated with reduced lung function and other respiratory diseases. However, the contribution of PM elemental components to respiratory effects remains largely unknown. Aims: To evaluate in a highly-exposed population in Beijing, China, whether exposure to PMand its elemental componentsaffects lung function. Methods: The Beijing Truck-Driver Air Pollution Study conducted shortly before the 2008 Olympic Games (June 15-July 27, 2008) included 60 truck drivers and 60 office workers. On 2 days separated by 1-2 weeks, personal PM2.5 was measured gravimetrically during work hoursusing portable monitors. Eight selected element components (i.e. potassium (K), sulfur (S), iron (Fe), silicon (Si), aluminium (Al), zinc (Zn), calcium (Ca) and titanium (Ti)) were measured by XRF PANanalytical Epsilon 5 analyzer. We measured 5 lung function indicators using EasyOne ultrasonic spirometer, including forced expiratory volume in one second (FEV1), forced vital capacity (FVC), FEV1/FVC, forced expiratory flow 25%-75% (FEF 25-75%), and peak expiratory flow (PFF). We examined the associations of exposures (PM2.5 and 8 components) with the indicators in mixed-effect models adjusted for confounding factors. Results:Mean personal PM2.5 was 126.8 µg/m3 in drivers and 94.6 µg/m3 in office workers (p<0.001). Mean levels of 8 elements in drivers were higher than that in office workers (p<0.001). We did not observe significant differences in the 5 indicators between drivers and office workers. In all subjects, FEV1 was negatively associated with concentrations of Si (-8.5%, 95%CI:-14.8; -2.2, p=0.025), Al (-7.7%, 95%CI:-14.3; -1.2, p=0.037), Ca (-5.1%, 95%CI:-8.6; -1.7, p=0.025), and Ti (-7.2%, 95%CI:-13.2; -1.3, p=0.037). These associations were weaker and non-significant in office workers, but stronger and significant in drivers. Conclusion: Concentrations of Si, Al, Ca, and Ti in particles were associated with decreased lung function. This may indicate an effect of road dust.