Psychological Impact of Vehicle Exhaust Exposure: Insights from an Animal Model

Air pollution resulting from exhaust emissions of vehicles has risen in the recent years, reportedly causing major adverse effects on the heart, lungs and the brain. Though respiratory and cardiovascular effects of these emissions are well identified, psychological and neurobiological complications of prolonged exposure to vehicle emissions remain unknown. Pro-oxidants are considered as major constituents of vehicle emissions. This is important considering causal link between oxidative stress and behavioral and cognitive impairments. We hypothesized that prolonged exposure to pro-oxidants in vehicle emissions result in behavioral and cognitive deficits. We developed a simulated vehicle exhaust exposure model in rats. The model used a simulated mixture of vehicle exhaust that comprised of pro-oxidant constituents of exhaust, namely, carbon dioxide (13%), carbon monoxide (0.68%) and nitrogen dioxide (1000 ppm) in air. Rats were exposed either to a high (1:10 dilution) or low (~1:1000 dilution) physiologically relevant dose of simulated mixture in air for two weeks in separate experiments followed by a comprehensive behavioral and cognitive analysis. We observed that prolonged exposure to pro-oxidants in vehicle exhaust increased anxiety-and depression-like behavior as well as led to impaired memory in rats. This is important preclinical evidence, particularly relevant to human population exposed to high vehicular traffic.