Air pollution
and its impact on health:
Comparing findings in China with findings in
Europe and the USA
Kristin Aunan, CICERO
CCICED, October 29, 2007, Beijing
16 of the 20 most polluted cities in the
world are Chinese
What are the health benefits of abating air pollution?
Delhi
Mexico City
Rio de Janeiro
NO2
Los Angeles
SO2
New York
TSP
Tokyo
Shanghai
Lanzhou
Taiyuan
Guangzhou
Beijing
0
100
200
300
400
mg/m
Policy
option
Emission
Exposure
500
600
700
800
3
Exposure
response
Physical
benefit
Valuation
Monetary
benefit
2
Deaths from diseases associated with
air pollution exposure are frequent in
China (2002)
Annual deaths per 100,000 people. Source: WHO, 2004
3
Why should there be differences
between d-r coefficients across
countries?
• Differences in
composition of air
pollution
• Demographic factors,
e.g. age distribution
• Health status and socioeconomic conditions
• Access to health
services
4
.. differences may (misleadingly)
be due to
• Confounding factors
(e.g. exposure to
indoor air pollution)
• Conversion factors
between different
PM fractions (e.g.
TSP to PM10)
• Classification of
disease (ICD 9, ICD
10)
5
Dose-response for acute all-cause
mortality (time-series studies): Very
good agreement across regions
Percent change in health outcome per 1 mg/m3
USA
USA
(NMMAPS)
Harvard 6 cities
Reanalysis
Reanalysis
0.04-0.06
0.02-0.03
0.07
0.03-0.06
No evidence
Not included
End-point
China (meta-analysis)
Europe (APHEA II)
(air pollutant)
Aunan & Pan, 2004
Reanalysis
All-cause deaths 0.03
(PM10)
(HEI, 2004: 0.04-0.05)
All-cause deaths 0.04
(SO2)
(HEI, 2004: 0.04-0.05)
(Eastern Europe:
0.01-0.04
Western Europe:
0.03-0.06)
6
Dose-response for other end-points
(time-series and cross-sectional
studies): Less agreement
End-point (air
pollutant)
Hosp. admissions (CVD)
P10
Hosp. admissions (CVD)
SO2
Hosp.admissions (resp.)
PM10
Hosp.admissions (resp.)
SO2
Chronic Resp. illness
Adults PM10
Chronic Resp. illness
Children PM10
Chronic bronchitis Adults
PM10
Chronic bronchitis
Children PM10
China (meta-analysis)
Aunan & Pan, 2004
Europe (APHEA II)
0.07
0.04-0.05
0.19
0.07
0.12
(HEI, 2004: 0.07-0.16)
0.15
0.09
Europe (Kunzli
metaanalysis)
USA
0.13
0.10
0.13
0.10-0.40
NMMAPS (US-EPA, 2003)
NMMAPS (US-EPA, 2003)
0.05
0.31
0.44
Portnay Mullahy, 1990;
0.48
0.91-1.27
Schwartz, 1993; Abbey et al.,
1993
0.34
2.5
Ware et al., 1996; Dockery et al.,
1989
Meta-analysis (Eastern Europe,
Infant mortality
0.39
USA, S.Korea, Mexico) (Aunan
and Pan, 2004)
7
Generally: Large variations across
studies for most end-points
Dose-Response (% change in response per mg/m3)
1.25
Meta analysis
4.8
95% CI )low)
95% CI (high)
1.00
a
b
c
0.75
d
e
f
Western
0.50
0.25
0.00
8
How to deal with long-term
effects on mortality in China?
• Shortterm time-series studies do not capture
the long-term cumulative effects of pollution
exposure
• No long-term cohort studies in China (or
similar countries)
• Cohort studies from USA (Pope et al., 1995,
2002) yield implausibly high risks in China
• World Bank 2007: Use Pope et al. (low
pollution areas) and cross-sectional Chinese
studies (high pollution areas -Shenyang and
Benxi) and adjust a logarithmic function
9
A compromise solution
(gives around 400,000 premature deaths in urban
China in 2003)
10
Avoided deaths mean life years
gained
Life years gained per person in cohort, estimated for a 10
mg/m3 reduction in PM10 exposure (Chinese life table for
2003 and Pope et al. Dose-response coefficient).
Dlife expectancy at birth:~0.3 year
0.16
0.12
0.10
0.08
0.06
0.04
0.02
Years of age
90
-
59
10
-1
4
15
-1
9
20
-2
4
25
-2
9
30
-3
4
35
-3
9
40
-4
4
45
-4
9
50
-5
4
55
-5
9
60
-6
4
65
-6
9
70
-7
4
75
-7
9
80
-8
4
85
-8
9
14
0.00
01
Potential life years gained
0.14
(From Aunan et al., 2004)
11
USA
Six cities study (Dockery et al. 1993):
Dlife expectancy at birth: ~ 0.8 year per 10 mg/m3 PM10
Figure taken from J. Schwartz, testimony, 2007
12
COPD: An important health
endpoint for which knowledge is
scarce
What is the incidence rate and prevalence rate in
China? Regional differences?
Global Health Statistics, Murray and
Lopez, 1996
Incidence rate 1990
Prevalence rate 1990
Average duration
345
Per 100,000
2499
Per 100,000
7.8
years
750
Per 100,000
Ministry of Health, 2004
1/2 year prevalence
(huan bin lu)
Estimated average duration
12.8 (?)
years
13
Conclusions
• Acute effect om premature mortality:
– High degree of certainty and coherence across
regions (d-r and baseline rates)
– But no studies on infant mortality
• Better to transfer d-r for chronic mortality effects
than to omit
– Long-term cohort studies in China needed!
• Chronic respiratory diseases (e.g. COPD):
– Large uncertainties remain (d-r and baseline
rates)
• Data on present frequencies of health outcomes
and exposure levels are insufficient, especially in
rural areas
14