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

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AIR QUALITY GUIDELINES
2005 (136). Daily measurements of five pollutants (PM10, ozone, nitrogen dioxide,
carbon monoxide and sulfur dioxide) were available from January 1993
to August 2000. The mean daily 1-hour maximum nitrogen dioxide value was
45.9 ppb. Detailed measurements of PM were available for 24 months. Visits for
asthma, COPD, upper respiratory infections and pneumonia were evaluated.
Considering an a priori three-day lag (lag 0–2), PM10, ozone, nitrogen dioxide
and carbon monoxide were associated with all respiratory admissions and with
upper respiratory infections. The effect for 20 ppb 1-hour nitrogen dioxide was
1.6% (95% CI 0.6–2.7) for all respiratory conditions and 1.9% (95% CI 0.6–3.1)
for upper respiratory infections. Visits for COPD were associated only with
1-hour nitrogen dioxide (3.5% per 20 ppb, 95% CI 0.6–6.5) and carbon monoxide.
For asthma, a stronger effect was detected considering distributed lag models
(lags 0–13 days), with PM10, nitrogen dioxide (4.7% for 20 ppb, 95% CI 1.1–8.5)
and carbon monoxide showing a statistically significant effect. Paediatric asthma
visits (ages 2–18 years) showed a strong association only with nitrogen dioxide
(2.7% per 20 ppb, 95% CI 0.5–5.0). In multi-pollutant models, the nitrogen dioxide
effects were attenuated when PM10, nitrogen dioxide and carbon monoxide
were considered simultaneously. However, the effect of nitrogen dioxide on
emergency visits for asthma was not attenuated in multi-pollutant models, while
the estimates for the other pollutants suggested a weak association or none at all.
Observations are also available on nitrogen dioxide and hospital admissions
for cardiovascular diseases. In the studies by Polonieski et al. (148) (myocardial
infarction), Burnett et al. (149) (all cardiovascular admissions), Burnett et al.
(150) (ischaemic heart disease, heart failure), Atkinson et al. (151) (all cardiovascular),
Wong e al. (152) (all cardiovascular, heart failure) and D’Ippoliti et al.
(153) (myocardial infarction), a statistically significant effect was found for nitrogen
dioxide. In some of these studies, the effect estimates were moderated and
sometimes became non-significant when the investigators controlled for particle
concentrations. In the studies by Schwartz (154) (all cardiovascular) and Morris
et al. (155) (heart failure), no effect of nitrogen dioxide was found.
Two recent large American studies evaluated nitrogen dioxide and other pollutants
and their relationship with hospital admissions for ischemic heart disease
(156) and visits to emergency departments for cardiovascular problems (134).
Mann et al. (156) examined whether admissions for ischemic heart disease were
associated with air pollutants in subjects with and without secondary diagnoses
of arrhythmia or congestive heart failure, using a large data set of members of a
large health maintenance organization who resided in the South Coast Air Basin
of California from 1988 to 1995. Daily variations in carbon monoxide, nitrogen
dioxide, ozone and PM10 were considered. Carbon monoxide and nitrogen dioxide
(mean 37.2 ppb, interquartile range 3.7–138) were both associated with admissions,
with the greatest effects for carbon monoxide. PM10 was not associated
with hospital admissions in this study but particle concentrations were available