Black Carbon Air Pollution may Lower IQ

Joel D. Schwartz, Ph.D.
Harvard School of Public Health
NIEHS Grants R01ES015172, P30ES000002, and T32ES007142

Children who live in neighborhoods with heavily polluted by automobile traffic have lower IQs. They also score worse on other intelligence and memory tests than children in healthier environments according to a new study by NIEHS supported researchers and the Harvard School of Public Health. These findings raise additional concerns about the health of children living in generally poor urban environments near transportation corridors or heavy industry.

The respiratory and cardiovascular effects of air pollution are well documented; however the possible neurodegenerative effects of air pollution have been largely unexplored. The Harvard group’s results show dramatic differences in the 202 children they examined. These kids ranged in age from eight to eleven years and were from the Boston, MA area. The more heavily exposed children were to black carbon, the lower their scores on several intelligence tests. For example, the average IQ of the most heavily exposed children was 3.4 points less than children with low exposure. When the researchers adjusted for the effects of parents’ education, birth weight, and exposure to tobacco smoke, the associations remained. The effects were roughly equivalent to those seen in children whose mothers smoked ten cigarettes per day while pregnant.

The researchers speculate that the harmful effects may be caused by the inflammatory and oxidative effects of the black carbon particles. These findings suggest additional research is warranted to investigate the effects of air pollution on the development of intelligence in children and on cognitive decline for people of all ages.

Citation: Suglia SF, Gryparis A, Wright RO, Schwartz J, Wright RJ. Association of black carbon with cognition among children in a prospective birth cohort study. Am J Epidemiol. 2008 Feb 1;167(3):280-6.