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

NITROGEN DIOXIDE
Nitrogen dioxide
unit (mean)
Annual averages,
categories of quartiles
10 μg/m 3 (modelled 10year
average)
Modelled (range 1.5–28
ppb)
10 μg/m3 (range 12–61
μg/m3 ; after exclusion
(18 areas) range 12–32
μg/m3 )
30 μg/m3 (range of
annual averages
14.7–67.2 μg/m3 )
Increment not given
(mean (SD) 1980: 27.9
ppb (9.2 ppb))
Nitrogen dioxide
effect estimate
(95% CI)
No estimate for
continuous exposure
given
1.10 (0.97–1.23)
adjusted
No estimate for
continuous exposure
given
24 areas: 0.97 (0.85–
1.10)
18 areas: 1.48 (1.05–
2.06), both adjusted
1.25 (0.42–3.72)
adjusted
Estimates only reported
as figure
Comments
365
Range of nitrogen dioxide exposure is not
reported. A relative risk estimate of 2.7 (95%
CI 0.9–8.5) was found for total cancer at
nitrogen dioxide concentrations of 50 μg/m3 or higher compared to 39 μg/m3 or lower.
At 80 μg/m3 the relative risk was 3.8 (95% CI
1.2–12.1).
Full range of exposure not reported. Results
were robust against consideration of sulfur
dioxide concentrations. There might be a
suggestion of a threshold at around
30 μg/m3 nitrogen dioxide.
Nitrogen dioxide and benzene were
modelled based on a validated model
at residential address for pregnancy and
childhood. Exposure is expressed per 1000
ppb-person-days. No overall increased risk
observed, but malignant lymphomas were
increased in association with exposure
to nitrogen dioxide and benzene during
pregnancy. Risk increases across quartiles
and positive test for trend.
No validation of cancer cases; no association
with other correlated pollutants and lung
cancer observed.
Only 60 cases were identified; no
validation of cancer cases. Estimates are
for background and local concentrations
combined.
No association observed for nitrogen
dioxide but observed for PM2.5. Neither
increments nor size of effects are reported.
Asthma, respiratory disorders and atopy
A large number of studies have assessed the association between respiratory morbidity
in adults and children, assessing nitrogen dioxide concentrations on an
area level, at the children’s school or at home. Studies include measurements of
nitrogen dioxide or modelled nitrogen dioxide concentrations. Both cross-sectional
and cohort studies have been conducted. In the text below, special attention
is paid to the cohort studies, as they could be regarded to be the most reliable
basis for setting air quality guidelines.