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

SULFUR DIOXIDE
Table 1. Estimated total (non-accidental) mortality expressed as percentage excess
deaths (95% CI in parentheses) per 50-μg/m 3 increase in sulfur dioxide reported in
recent multi-city time series studies and meta-analyses
Study
APHEA 1 (17),
12 European cities
APHEA 1 (19,20),
12 European cities,
using natural splines
rather than sine/
cosine to adjust for
temporal trends
EMECAM (21)
(GAM study),
13 Spanish cities
NMMAPS (22,23),
90 largest US cities
Stieb et al.
meta-analyses
(24,25)
Estimate
Western Europe: 2.9% (2.3–4.6) at the
best lag between 0 and 3 days for each
city
Central and eastern Europe: 0.9%
(0.2–1.5)
Western Europe: 2.6% (2.1–3.1)
Central and eastern Europe: 0.7%
(0.0–1.4)
2.5% (0.3–4.9), average of lag 0
and 1 days.
1.1% (0.5, 1.7) at lag 1 day
Non-GAM:
Single pollutant (29 studies): 1.7%
(1.2–2.3)
With co-pollutant(s) (10 studies): 1.6%
(0.6–2.5)
GAM:
Single pollutant (17 studies): 2.0%
(1.3–2.6)
With co-pollutant(s) (11 studies): 1.6%
(0.8–2.4)
Comment
The effects of sulfur dioxide
and PM were “mutually
independent”
pollutants. In two-pollutant models with PM indices, sulfur dioxide remained
more strongly associated with mortality than the PM indices. However, the authors
stated that “the persistence of the sulfur dioxide effect was interpreted as artefact,
because the sulfur dioxide concentration was much below levels at which
effects are usually expected”.
Wichmann et al. (38) noted that that the relative risk associated with sulfur
dioxide was rising as the concentrations in Germany declined through the 1980s
and 1990s, which they concluded was counterintuitive. They also noted that an
examination by Buringh et al. (40) of a nine-year time series study of the whole
Dutch population during a period of declining sulfur dioxide concentrations
came to a similar conclusion. These analyses clearly indicate that caution must
be exercised when considering whether low concentrations of sulfur dioxide
405
Restricting data range below
150 or 200 μg/m 3 increased
sulfur dioxide risk estimates
Adding co-pollutants reduced
the estimate by ~20% and
widened confidence bands