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

SULFUR DIOXIDE
regressions, also found that nitrogen dioxide was an important effect modifier
of PM (i.e. the cities with higher nitrogen dioxide levels showed larger PM risk
estimates) in total mortality (26,27) and in elderly mortality (28). While they did
not report numerical data, the results imply that the difference in sulfur dioxide
levels across cities did not alter the PM risk estimates. The median levels of sulfur
dioxide in these 29 cities ranged from 4 μg/m 3 (Stockholm) to 49 μg/m 3 (Cracow).
A Spanish multi-city study (EMECAM) analysed short-term associations between
mortality and sulfur dioxide and PM in 13 Spanish cities (21). Note that
this was a GAM study that has not been re-analysed. The study examined both
24-hour average and daily 1-hour maximum sulfur dioxide levels. The median
levels of sulfur dioxide in these 13 cities ranged from 8 μg/m 3 (Seville) to 45 μg/
m 3 (Oviedo). The results indicated that the estimated mortality risks for the 24hour
average sulfur dioxide were greatly reduced when two-pollutant models
with PM were performed, but the estimates for 1-hour maximum sulfur dioxide
were not attenuated by PM. The authors concluded that peak rather than daily
average concentrations of sulfur dioxide were related to mortality.
The largest American multi-city mortality study, the National Morbidity,
Mortality, and Air Pollution Study (NMMAPS), while its main focus was on PM