CONCLUSIONS
Almost all the values of PM10 at the high-polluted sites (H
area) in Bangkok exceeded the NAAQS. Although PM10
concentration measured by our sampler was 1.5 times the
PCD data, they were well correlated. The higher ratio of
coarse mass to fine mass in outdoor air and the higher
correlation coefficient of PM2.5 and PM2.5-10 in the H area
reflected the automobile sources. The personal exposure
level of police to PM was roughly the same as the atmospheric
PM level measured at the intersection, and the
exposure showed a significantly higher proportion of PM2.5
to PM10 in the H area than in the L area. The annual PM10
level at the roadside from the PCD monitoring data confirmed
the high particulate air pollution found by our
measurement and that automobile exhaust was the main
source of the particulate air pollution.
For future study, we also would emphasize the urgent
necessity to monitor the health effects of air pollution
in highly exposed groups, namely, traffic police, bus
drivers, and motorcycle messengers. Although a standard
method for monitoring air pollution has been implemented,
little information on the relationship between
exposure and chronic health effects has been available.
The existing monitoring procedures and standards may need to be revised to include specific measurement of the
fine particles as PM2.5.