Effects of fresh and aged traffic-related particles on breathing pattern, cellular responses, and oxidative stress

Air pollution is comprised of a complex mixture of gaseous and particulate pollutants emitted from multiple sources. During transport in the atmosphere, emissions undergo photochemical reactions, which may change their toxicity. Toxicological and epidemiological studies have linked vehicular emissions to respiratory and cardiovascular health effects. The aim of this study was to investigate the toxicity of primary and secondary traffic particles. Male Sprague–Dawley rats were exposed to either filtered air (control group) or one of three types of atmospheres: fresh primary particles from a major traffic tunnel plenum (P); secondary organic aerosol formed from photochemical oxidation of primary tunnel gases after filtration of primary particles (SOA); or photochemically aged primary particles plus secondary organic aerosols (P + SOA). In each exposure, 80–90 % of pollutant gases were removed using a non-selective denuder. Animals were exposed for 5 h per day, with varying number of days of exposure. Outcomes included: breathing pattern, broncho-alveolar lavage (BAL), complete blood count, and in vivo chemiluminescence (IVCL). Consistent mass concentration (approximately 50 μg/m3) was achieved for all exposures. Respiratory data showed many changes with each exposure type. All exposures produced decreases in tidal volume, minute volume, inspiratory and expiratory flows. There were mild inflammatory changes in BAL, with increased neutrophils for the SOA and P + SOA exposures and lymphocytes for the P and P + SOA exposure, with no changes in any test exposure for total protein, β-NAG or IVCL. All exposures produced changes compared to filtered air. Exposures containing particles (P and P + SOA) had stronger effects than SOA.