title: Neurobehavioral effects of ambient air pollution on cognitive performance in US adults.
abstract: BACKGROUND
  In vivo animal experiments demonstrate neurotoxicity of exposures to particulate matter (PM) and ozone, but only one small epidemiological study had linked ambient air pollution with central nervous system (CNS) functions in children.
  
  
  OBJECTIVE
  To examine the neurobehavioral effects associated with long-term exposure to ambient PM and ozone in adults.
  
  
  METHODS
  We conducted a secondary analysis of the Neurobehavioral Evaluation System-2 (NES2) data (including a simple reaction time test [SRTT] measuring motor response speed to a visual stimulus; a symbol-digit substitution test [SDST] for coding ability; and a serial-digit learning test [SDLT] for attention and short-term memory) from 1764 adult participants (aged 37.5+/-10.9 years) of the Third National Health and Nutrition Examination Survey in 1988-1991. Based on ambient PM(10) (PM with aerodynamic diameter <10microm) and ozone data from the EPA Aerometric Information Retrieval System database, estimated annual exposure prior to the examination were aggregated at the centroid of each census-block group of geocoded residences, using distance-weighted averages from all monitors in the residing and adjoining counties. Generalized linear models were constructed to examine the associations, adjusting for potential confounders.
  
  
  RESULTS
  In age- and sex-adjusted models, PM(10) predicted reduced CNS functions, but the association disappeared after adjustment for sociodemographic factors. There were consistent associations between ozone and reduced performance in NES2. In models adjusting for demographics, socioeconomic status, lifestyle, household and neighborhood characteristics, and cardiovascular risk factors, ozone predicted high scores in SDST and SDLT, but not in SRTT. Each 10-ppb increase in annual ozone was associated with increased SDST and SDLT scores by 0.16 (95%CI: 0.01, 0.23) and 0.56 (95%CI: 0.07, 1.05), equivalent to 3.5 and 5.3 years of aging-related decline in cognitive performance.
  
  
  CONCLUSIONS
  Our study provides the first epidemiological data supporting the adverse neurobehavioral effects of ambient air pollutants in adults.
authors.affiliation: Department of Epidemiology, UNC-School of Public Health, Chapel Hill, NC 27599-7435, USA. jcchen@unc.edu
authors.forename: Jiu-Chiuan
authors.initials: JC
authors.lastname: Chen
authors.forename: Joel
authors.initials: J
authors.lastname: Schwartz
mesh_terms: D000328:Adult; D000397:Air Pollution / Q000009:adverse effects*; D003071:Cognition / Q000187:drug effects* / Q000502:physiology; D005260:Female; D006306:Health Surveys; D006801:Humans; D008297:Male; D008875:Middle Aged; D052638:Particulate Matter / Q000009:adverse effects*; D011597:Psychomotor Performance / Q000187:drug effects* / Q000502:physiology; D014481:United States / Q000453:epidemiology; D055815:Young Adult
chemical_list: D052638:Particulate Matter