Air Quality Guidelines Global Update 2005 - World Health ...

PARTICULATE MATTER
Reference Population Follow-up Findings
Filleul
et al.
(301)
14 284 adults
who resided
in 24 areas in
7 French cities
when enrolled
in the PAARC
survey in 1974
25 years
incorporating exposure at the population level but with individual covariate data,
have been termed “semi-ecological”. Data from two of the studies, CPS II and the
Harvard Six Cities Study, have been independently re-analysed (248).
In general, the studies show a positive association between PM indicators and
total and cause-specific mortality, including cardiovascular diseases and lung
cancer. In the major studies, the findings are statistically significant and robust to
control for confounding, although the possibility of some confounding remains.
Morbidity
Overview
A wide range of morbidity indicators has been investigated in epidemiological
studies (Box 1 and Fig. 3); the populations have included infants, children, adults,
and various groups considered susceptible to PM. The outcomes include clinical
indicators such as hospital admission numbers and counts of visits to emergency
departments or clinics, symptom status in persons with underlying chronic heart
or lung disease, level of pulmonary function, and various biomarkers. The design
approaches include time series studies, “panel studies” or short-term cohort
studies of susceptible groups, and cross-sectional studies. Risk for acute events,
including myocardial infarction and stroke, has been assessed using the casecrossover
design. In this design, the individual is the unit of analysis and exposures
are compared in the “case” period during which the event of interest took
place and in one or more event-free “control” periods. As for mortality, the literature
on morbidity indicators in relation to PM is also substantial. The USEPA
criteria document (3) provides a summary through to 2004. Selected elements of
the evidence are considered in this chapter. This evidence is complementary to
the information on mortality, as it covers the full range of adverse health effects
from changes in biomarkers to clinical disease. Nevertheless, the recommendations
for specific guideline values are largely based on the mortality findings.
Reproductive outcomes
The developing fetus has long been considered at potentially increased risk from
exposures during critical periods of development. Maternal smoking is causally
associated with a number of adverse effects on reproduction, including increased
risk of miscarriage and a reduction of birth weight that averages approximately
263
Adjusted risk ratios (95% CI) for total
suspended particulates, BS, nitrogen dioxide,
and nitric oxide for non-accidental mortality
were 1.05 (1.02–1.08), 1.07 (1.03–1.10), 1.14
(1.03–1.25) and 1.11 (1.05–1.17) for 10 μg/m 3 ,
respectively.