Worst air pollution, worldwide
by annual mean fine particulate matter
1. Ahwaz, Iran
2. Ulaanbaatar, Mongolia
3. Sanandaj, Iran
4. (tie) Ludhiana, India
Quetta, Pakistan
6. Kermanshah, Pakistan
7. Peshawar, Pakistan
8. Gaborone, Botswana
9. Yasouj, Iran
10. Kanpur, India
11. Lahore, Pakistan
12. Delhi, India
13. Karachi, Pakistan
14. Islamabad, Pakistan
15. Lucknow, India
16. Rawalpindi, Pakistan
17. Uromiyeh, Iran
18. Qom, Iran
19. Indore, India
20. Khoramabad, Iran
University of Montana and the National Institute of Pediatrics in
Mexico City, has investigated the neurological effects of the city’s
infamous smog.
In early investigations, Calderón-Garcidueñas dissected
the brains of dogs that had been exposed to air pollution of
Mexico City and compared them with the brains of dogs from
a less-polluted city. She found the Mexico City dogs’ brains
showed increased inflammation and pathology including
amyloid plaques and neurofibrillary tangles, clumps of
proteins that serve as a primary marker for Alzheimer’s disease
in humans (Toxicologic Pathology, 2003).
In follow-up research, Calderón-Garcidueñas turned her
attention to Mexico’s children. In one study, she examined 55
kids from Mexico City and 18 from the less-polluted city of
Polotitlán. Magnetic resonance imagining scans revealed that
the children exposed to urban pollution were significantly
more likely to have brain inflammation and damaged tissue
in the prefrontal cortex. Neuroinflammation, Calderón-Garcidueñas explains, disrupts the blood-brain barrier and is a
key factor in many central nervous system disorders, including
Alzheimer’s disease and Parkinson’s disease. Perhaps more
troubling, though, the differences between the two groups of
children weren’t just anatomical. Compared with kids from
cleaner Polotitlán, the Mexico City children scored lower
on tests of memory, cognition and intelligence (Brain and
Cognition, 2008).
3
6 MONITOR ON PSYCHOLOGY • JULY/AUGUST 2012 Source: World Health Organization, 2003–10, www.who.int/phe/health_topics/outdoorair/databases/en
Brain changes
It’s becoming clearer that air pollution affects the brain, but
plenty of questions remain. Randy Nelson, PhD, a professor
of neuroscience at the Ohio State University, is using mouse
studies to find some answers. With his doctoral student Laura
Fonken and colleagues, he exposed mice to high levels of fine
particulate air pollution five times a week, eight hours a day,
to mimic the exposure a human commuter might receive if
he or she lived in the suburbs and worked in a smoggy city
(Molecular Psychiatry, 2011). After 10 months, they found that
the mice that had been exposed to polluted air took longer
to learn a maze task and made more mistakes than
mice that had not breathed in the pollution.
Nelson also found that the
pollutant-exposed mice
showed signs of the
rodent equivalent
of
