Health Effects of Aerosols - Aerosols: Measurement, Dosimetry, and Health Effects - page 622

2.5

(C.I. = 3.04)

Legend

Adults
All children
Symptomatic and/or
asthmatic children
Range represents 95%
confidence level

2.0

1.5

1

Adults Children

0.5

1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 6 7 8 9 10 11 12 8 13 14 15 16 17 15 16 17 18 15 16 17 18

Total
mortality

Respiratory
mortality

Cardiovascular
mortality

Respiratory
hospital
admissions

COPD or IHD
hospital
admissions

Cough Lower

respiratory
symptoms

Upper
respiratory
symptoms

FIGURE 23.35 RRs of various health outcomes per 50 μg/m 3 increase in PM 10 for adults and children. Each
data point and error bar represents a separate study. (From Federal Register, National ambient air quality
standard for particulate matter, Report No.: 40 CRF Part 50, National Archives and Records Administration,
Washington, DC, December 1996.)

Thus, while the deinitive physiological mechanisms that might underlie the association between
increases in daily cardiovascular mortality with daily increase in PM aerosol are not known deini-
tively, what is known is supportive of the fact that the association is likely to be causal and not
due to some unmeasured confounding factors or some subtle problem with the statistical analysis
approaches that have been employed by epidemiological studies. A similar case can be made for
deaths from chronic lung disease, based on the expected results of the pro-inlammatory properties
of the ambient PM aerosol.

23.6 CONCLUSIONS
This chapter has focused largely on the effects of the nonradioactive, nonoccupational, ambient
PM aerosol and its likely effect on human health. The chapter has been representative, rather than
exhaustive, in its synthesis of current data. Only selected areas related to human health have been
discussed. The most exhaustive review of the material presented herein can be found in the descrip-
tive sections of the most recent public release of the draft document for PM standard being circu-
lated for review by the U.S. EPA [264].
While there is little controversy about the effects of the bioaerosol component of the ambient PM
aerosol on human health, there has been more skepticism about the effects of the anthropogenic com-
ponent of the PM aerosol on human health, as clearly indicated by epidemiological studies. However,
there now appears a suficient body of basic biological and physiological mechanistic research data
that makes it far more likely that the observed associations between the anthropogenic component of
the PM aerosol and human health are causal than are the methodological issues related to epidemio-
logical study designs, statistical analysis, and issues related to exposure measurement error.

REFERENCES

1. Donaldson, K., Beswick, P.H., and Gilmour, P.S., Free radical activity associated with the surface of
particles: A unifying factor in determining biological activity? Toxicol. Lett ., 88, 293-298, 1996.

2. U.S. Environmental Protection Agency (EPA), Air quality criteria for particulate matter—Third external
review draft, EPA 600/P-99/002aC, Report No.: EPA 600/P-99/002aC, Research Triangle Park, NC, 2001.