The effects of traffic-related air pollution on cognitive functions and behavior in humans : a systematic review

Abstract

Objective To investigate whether traffic pollutants have any effect on human cognitive functions and behavior by performing a systematic review on existing research studies. Methods Research articles were identified through four databases – CINAHL Plus, Academic Search Premier and MEDLINE via EBSCOhost and Pubmed using the online electronic resources of the libraries of the Hong Kong University. A total of 119 articles from Pubmed and 86 articles from EBSCOhost were identified, and 72 and 64 studies after limits were applied. The studies used a variety of measures to assess the effects of traffic-related air pollution and cognitive functions and behaviors in both children and adults. Results There were 19 articles in total in the systematic review – 13 on children (aged from 1- 17 years) and six on adults (aged from 26 - 83.5 years). Data were employed from nine different countries. Although there were some discrepancies in the results, there was evidence of the effects of traffic-related air pollution on the brain. Conclusions The causal relationship between traffic-related air pollution and cognitive decline cannot be clearly determined. The systematic review however, generated evidence to support the hypothesis that traffic-related air pollution may affect cognitive development in children, increase risks of behavioral disorders in both children and adults, and increase the rate of cognitive decline in older adults. As a result, this systematic review suggests that the research findings have important implications in the development of public health policy and practice.