risk-based air pollutants management at regional levels

9
Risk-based air pollutants management at regional levels Jianhua Xu a,b , Xuesong Wang c, *, Shiqiu Zhang a a Department of Environmental Management, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, PR China b Center for Crisis Management Research, School of Public Policy and Management, Tsinghua University, Beijing 100084, PR China c Department of Environmental Sciences, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, PR China 1. Introduction The ultimate objective of abating pollutant emissions is to protect the health and welfare of the public. Methods for estimating damages to health and welfare from air pollution are well established (e.g., USEPA, 1999; Bickel and Friedrich, 2005; Holland et al., 2005, 2011; Ho and Nielsen, 2007; Muller and Mendelsohn, 2007), while in practice, in assigning control responsibility and designing control options for conventional air pollutants, health and welfare were seldom used as the direct target, largely due to the huge amount of information needed to estimate damages to health and welfare and the inherent uncertainties embedded in such an estimation (Tietenberg, 1995). Often, emissions or concentrations are used as the direct target; handy examples include the pollution levy system and SO 2 total emissions control system in China and the SO 2 emission trading program in the United States. It should be kept in mind that policies as such were developed decades ago. As computing power increases, air pollutants’ fate and transport modeling capabilities advance, and risk assessment evolves, it becomes more feasible than ever to use health risks posed by air pollutants as the direct policy target to improve the efficiency of society’s resource utilization. Actually, risk-based approaches have been widely used to assess the impact of energy utilization and evaluate e n v i r o n m e n t a l s c i e n c e & p o l i c y 2 5 ( 2 0 1 3 ) 1 6 7 1 7 5 a r t i c l e i n f o Published on line 8 November 2012 Keywords: Risk-based approach Regional air pollution SO 2 Beijing–Tianjin–Hebei region a b s t r a c t The ultimate objective of abating air pollution is to protect the health and welfare of the public, while in the past, health and welfare are seldom used as the direct policy target. Often, emissions or concentrations are used as the direct target. In this paper, we put heavy weight on the justification of using a risk-based approach to address air pollution problems, and use a case study to demonstrate its technical feasibility in a Chinese setting. In the case, we study the health risks associated with SO 2 emissions from the different sectors in Beijing and its surrounding areas (the Beijing–Tianjin–Hebei region), to inform control responsibili- ty assignment and control option design. The emission inventory was classified by sectors according to Chinese Standard Industrial Classification of All Economic Activities. The Community Multi-scale Air Quality (CMAQ) modeling system is used to simulate the fate and transport of SO 2 in the study region. Intake fraction, which is defined as the incremental intake per unit of pollutant released from a source or a category of sources, is borrowed to indicate the marginal risk posed by SO 2 from the major sectors. The results show that the intake fraction avoided per unit of SO 2 emissions abated from the four major sectors (power sector, smelting and pressing of ferrous metals, manufacture of non-metallic mineral products, and chemical industry) varies greatly, which implies that using a risk-based approach has the potential to help improve the efficiency in resource utilization for assign- ing pollutant control responsibilities and prioritizing pollutant control options. # 2012 Elsevier Ltd. All rights reserved. * Corresponding author. Tel.: +86 10 62758784. E-mail addresses: [email protected] (J. Xu), [email protected] (X. Wang), [email protected] (S. Zhang). Available online at www.sciencedirect.com journal homepage: www.elsevier.com/locate/envsci 1462-9011/$ see front matter # 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.envsci.2012.09.014

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Risk-based air pollutants management at regional levels

Jianhua Xu a,b, Xuesong Wang c,*, Shiqiu Zhang a

aDepartment of Environmental Management, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, PR ChinabCenter for Crisis Management Research, School of Public Policy and Management, Tsinghua University, Beijing 100084, PR ChinacDepartment of Environmental Sciences, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, PR China

e n v i r o n m e n t a l s c i e n c e & p o l i c y 2 5 ( 2 0 1 3 ) 1 6 7 – 1 7 5

a r t i c l e i n f o

Published on line 8 November 2012

Keywords:

Risk-based approach

Regional air pollution

SO2

Beijing–Tianjin–Hebei region

a b s t r a c t

The ultimate objective of abating air pollution is to protect the health and welfare of the

public, while in the past, health and welfare are seldom used as the direct policy target.

Often, emissions or concentrations are used as the direct target. In this paper, we put heavy

weight on the justification of using a risk-based approach to address air pollution problems,

and use a case study to demonstrate its technical feasibility in a Chinese setting. In the case,

we study the health risks associated with SO2 emissions from the different sectors in Beijing

and its surrounding areas (the Beijing–Tianjin–Hebei region), to inform control responsibili-

ty assignment and control option design. The emission inventory was classified by sectors

according to Chinese Standard Industrial Classification of All Economic Activities. The

Community Multi-scale Air Quality (CMAQ) modeling system is used to simulate the fate

and transport of SO2 in the study region. Intake fraction, which is defined as the incremental

intake per unit of pollutant released from a source or a category of sources, is borrowed to

indicate the marginal risk posed by SO2 from the major sectors. The results show that the

intake fraction avoided per unit of SO2 emissions abated from the four major sectors (power

sector, smelting and pressing of ferrous metals, manufacture of non-metallic mineral

products, and chemical industry) varies greatly, which implies that using a risk-based

approach has the potential to help improve the efficiency in resource utilization for assign-

ing pollutant control responsibilities and prioritizing pollutant control options.

# 2012 Elsevier Ltd. All rights reserved.

Available online at www.sciencedirect.com

journal homepage: www.elsevier.com/locate/envsci

1. Introduction

The ultimate objective of abating pollutant emissions is to

protect the health and welfare of the public. Methods for

estimating damages to health and welfare from air pollution

are well established (e.g., USEPA, 1999; Bickel and Friedrich,

2005; Holland et al., 2005, 2011; Ho and Nielsen, 2007; Muller

and Mendelsohn, 2007), while in practice, in assigning control

responsibility and designing control options for conventional

air pollutants, health and welfare were seldom used as the

direct target, largely due to the huge amount of information

needed to estimate damages to health and welfare and the

* Corresponding author. Tel.: +86 10 62758784.E-mail addresses: [email protected] (J. Xu), [email protected]

1462-9011/$ – see front matter # 2012 Elsevier Ltd. All rights reservedhttp://dx.doi.org/10.1016/j.envsci.2012.09.014

inherent uncertainties embedded in such an estimation

(Tietenberg, 1995). Often, emissions or concentrations are

used as the direct target; handy examples include the

pollution levy system and SO2 total emissions control system

in China and the SO2 emission trading program in the United

States. It should be kept in mind that policies as such were

developed decades ago. As computing power increases, air

pollutants’ fate and transport modeling capabilities advance,

and risk assessment evolves, it becomes more feasible than

ever to use health risks posed by air pollutants as the direct

policy target to improve the efficiency of society’s resource

utilization. Actually, risk-based approaches have been widely

used to assess the impact of energy utilization and evaluate

.cn (X. Wang), [email protected] (S. Zhang).

.

e n v i r o n m e n t a l s c i e n c e & p o l i c y 2 5 ( 2 0 1 3 ) 1 6 7 – 1 7 5168

the cost and benefit of air pollution control policies in Europe

(Bickel and Friedrich, 2005; Holland et al., 2005, 2011). Concerns

on using health risks as the direct policy target includes

unequal treatment of people exposed in polluted air as people

in populous areas are given heavier weight (Tietenberg, 1995),

and the tediousness and uncertainties in estimating risks

incurred by individual sources (Wesson et al., 2010). In its 2004

report Air Quality management in the United States, the National

Research Council (NRC, 2004) recommended a risk-based

approach to enhance air quality management in the United

States. Wesson et al. (2010) demonstrated the technical

feasibility of applying a risk-based approach to address air

pollution problems in the United States. In this paper, we use

health risks as the direct policy target to inform air quality

management in the Beijing–Tianjin–Hebei region (Fig. 1) as an

exploration of its technical feasibility in a Chinese setting.

Using risks posed by air pollutants as the direct policy

target to address air pollution problems in China has been

discussed in academia for a while. Florig et al. (2002) advocates

the adoption of exposure-based controls of particulate

emissions to improve the economic efficiency of public health

protection, and proposes ways in which exposure-based

controls might be applied under the current regulatory regime

(e.g., setting atmospheric emission limits according to the size

of the population affected). Florig et al. (2002) also mentioned

that one of the barriers to exposure-based regulation is the

paucity of data and limited local analytic capacity in modeling

the fate and transport of air pollutants, especially in less

developed regions. In the book Clearing the Air: the Health and

Economic Damages of Air Pollution in China edited by Ho and

Nielsen (2007), an analysis integrating economic growth,

energy use, air pollution and health damages was depicted.

It details the estimation of national health damages posed by

total suspended particulate (TSP) and SO2 emissions from

different sectors (e.g., power plants, chemicals industry, and

metals smelting and pressing). Facing the challenge of sparse

pollution data and limited health studies in China, this

research used the derived relationship between exposure risk

and emission source characteristics in sampled cities to

estimate the exposure risk in other parts of the country,

Fig. 1 – The Beijing–Tianjin–Hebei r

avoiding the need to conduct air fate and transport modeling

work. This work has great implications on attributing national

health damage by sectors and setting national mitigation

priorities regarding TSP and SO2. Zhou et al. (2010) estimated

the health risks posed by PM2.5 and O3 from four sectors (power

plants, industrial sources, mobile sources, and domestic life)

in the Yangzte River Delta and found that the health risks

avoided per tonne of PM2.5, NOx, VOC or SO2 emissions

reduction in these sectors are quite different in this delta,

which is informative for setting PM2.5 and O3 control strategies

in the Delta.

Our study focuses on estimating health risks posed by SO2

emissions from the different sectors at a regional level using a

case study, which is expected to inform control responsibility

assignment and control options prioritization for primary

pollutants. In the following, we describe the case, depict the

method, show the results as we go through the procedures in

the method section, and then draw conclusions, followed by

implications.

2. Case description – the Beijing–Tianjin–Hebei region

The Beijing–Tianjin–Hebei region is chosen to conduct the

case study, because firstly this region is experiencing severe

air pollution, secondly detailed pollutant emission data in this

region is readily available, and thirdly policy makers in this

region is soliciting suggestions on developing regional air

quality management mechanisms.

The Beijing–Tianjin–Hebei region, consisting of Hebei

province and the municipalities of Beijing and Tianjin

(Fig. 1), is located in northeast China, and covers an area of

212,800 km2 (about 2.2% of the total land area in China). There

are 13 cities at a prefecture-level or above (the 11 cities in Hebei

plus Beijing and Tianjin) in this region with 6 of them having a

population over 1 million. The 13 cities are inter-linked by

vibrant commercial activities and convenient transportation

(Chen and Lu, 2008). This region has a population of about 100

million, accounting for 7.5% of the national total, and

egion and its location in China.

Fig. 2 – SO2 emissions and annual average SO2 concentrations in Beijing, Tianjin and Hebei province.

Data sources: China Statistical Yearbook (2001–2010); Beijing Environmental Statement (1998–2010); Tianjin Environmental

Statement (1998–2010); Hebei Environmental Statement (1998–2010).

e n v i r o n m e n t a l s c i e n c e & p o l i c y 2 5 ( 2 0 1 3 ) 1 6 7 – 1 7 5 169

contributes about 10% of the gross domestic products (GDP) in

2009 (National Bureau of Statistics, 2010a). Within the region,

the tertiary industry in Beijing, Tianjin and Hebei contributes

75.5%, 45.3%, and 35.2% of the local GDP, respectively, and the

secondary industry in Tianjin and Hebei contribute about

53.0% and 52.0% of the local GDP, respectively in 2009 (National

Bureau of Statistics, 2010a). The stock of motor vehicles in two

mega-cities (Beijing and Tianjin) increased exponentially in

the past ten years, and reached 5 million in Beijing1 and 1.8

million in Tianjin in 2011. In 2009, the coal consumption in this

region amounted up to 333 million tonnes, accounting for

10.3% of the total national consumption (National Bureau of

Statistics, 2010b).

The Beijing–Tianjin–Hebei region suffers from severe air

pollution. Wind-blown dust, coal combustion, vehicular

emissions, and industry activities all contribute to the

unhealthy air in this region. Comparing daily Air Pollution

Index (API) in 86 major cities in 2010,2 we found that Beijing,

Tianjin and Shijiazhuang (the capital of Hebei province)

ranked 5, 19 and 24, respectively, in the medium value of

daily API, and ranked 4, 8 and 22, respectively, in the number of

days on which API exceeds 100 (100 is a value below which the

air quality is regarded as acceptable and posing little harm to

the health of the general public).

Anthropogenic SO2 are largely emitted from the burning of

fossil fuels and the extracting of metals from ores, in which

sulfur and its compounds exist as ‘‘impurities’’. In 2003, China

consumed 31% of the world’s coal. Burning coal contributes

more than 90% of the national SO2 emissions (Zhang, 2007). A

total annual amount of 22 Tg SO2 was discharged on average

in the most recent ten years, which is about 1/3 of the global

level (Smith et al., 2001; Stern, 2005). The SO2 emissions and

annual average concentrations during the past ten years in

the study region are shown in Fig. 2. The downward trend in

1 Beijing Traffic Management Bureau, http://ww.bjjtgl.gov.cn/publish/portal0/ (accessed 18.01.12).

2 The daily Air Pollution Index (API) of 86 major cities are avail-able on the website of the Ministry of Environmental Protection.http://datacenter.mep.gov.cn/. In mid-2010, more cities are addedto the list. Now, the daily API of 120 cities are available online.

both emission and concentration can be seen in the past five

years. Particularly, since 2009, the annual average SO2

concentrations in Beijing, Tianjin and Hebei all fall below

60 mg/m3, which is the grade II value in the Chinese National

Ambient Air Quality Standard (CNAAQS). However, the

monitoring data from June 2009 to December 2010 in 25 sites

covering the study region, provided by researchers from the

Institute of Atmospheric Physics, Chinese Academy of

Sciences, shows that the daily SO2 concentrations in this

region during the heating season (November–March) quite

often violate grade II daily SO2 CNNAQS (150 mg/m3). SO2

pollution is still severe albeit the improvement.

3. Method and results

The method for estimating health risks from air pollutants

emissions, which is an instance of the driving forces,

pressures, states, impacts and responses (DPSIR) framework

(Kristensen, 2004), has been well-documented and widely

applied (USEPA, 1999; Bickel and Friedrich, 2005; Ho and

Nielsen, 2007). Normally, it involves all or part of the following

procedures: (1) create emission inventories, (2) model the fate

and transport of pollutants, (3) estimate the distribution of the

population and their exposure, and (4) evaluate the health

risks posed by the pollutants. In the following sub-sections, we

detail how the procedures described above are followed to

estimate the health risks associated with SO2 emissions from

the different sectors in the study region.

3.1. SO2 emissions in the study region

We use 2006 SO2 emission inventory, which was constructed

in previous research on air quality assurance for the Beijing

Olympics by our colleagues and their collaborators. Based on

this inventory, the total emission of SO2 in the Beijing–

Tianjin–Hebei region reached 2.07 Tg in 2006 which is 5%

higher than the emissions provided in China Statistical

Yearbook 2007 (National Bureau of Statistics, 2007). The

emission inventory is classified by sectors according to the

Chinese Standard Industrial Classification of All Economic

Table 1 – The top 10 sectors in SO2 emissions in the study region.

Sector Emission (tonnes) Percentage Cumulative percentage

Production and distribution of electric power and heat power 1,544,443.4 74.91 74.91

Smelting and pressing of ferrous metals 141,016.1 6.84 81.75

Manufacture of non-metallic mineral products 109,643.8 5.32 87.07

Manufacture of raw chemical materials and chemical products 73,053.8 3.54 90.62

Processing of petroleum, coking, processing of nuclear fuel 40,259.2 1.95 92.57

Manufacture of paper and paper products 19,375.5 0.94 93.51

Mining and washing of coal 18,471.0 0.90 94.41

Manufacture of foods 9924.9 0.48 94.89

Manufacture of textile 8736.6 0.42 95.31

Manufacture of metal products 6725.9 0.33 95.64

Table 2 – SO2 emission reduction scenarios designed forsimulation.

Scenario Scenario description

Scenario 1 Baseline scenario, no actions are taken

Scenario 2 Solely reduce 30% of the emissions from

point sources in the sector of ‘‘production

and distribution of electric power and heat

power’’

Scenario 3 Solely reduce 30% of the emissions from

point sources in the sector of ‘‘smelting and

pressing of ferrous metals’’

Scenario 4 Solely reduce 30% of the emissions from

point sources in the sector of ‘‘manufacture

of non-metallic mineral products’’

Scenario 5 Solely reduce 30% of the emissions from

point sources in the sector of ‘‘manufacture

of raw chemical materials and chemical

products’’

Scenario 6 Solely reduce 30% of the emissions from

point sources in the sectors other than the

above four major sectors

e n v i r o n m e n t a l s c i e n c e & p o l i c y 2 5 ( 2 0 1 3 ) 1 6 7 – 1 7 5170

Activities, and a total of 95 sectors are identified. In the

original inventory, the emission sources in Hebei were well-

classified, while the emission sources in Beijing and Tianjin

were not. The Beijing and Tianjin sources were then classified

manually according to the products and services they provide

which are obtained from the website according to their

names. Table 1 shows the top 10 sectors in SO2 emissions in

the study region. The top 4 emissions sectors account for

more than 90% of the total regional emissions, which are the

major sectors that we are interested in.

3.2. Modeling

We would like to investigate how the emission reductions in

the major sectors affect the concentrations of SO2 in sub-areas

of the region. The major sectors includes the top 4 emission

sectors which are ‘‘production and distribution of electric

power and heat power’’, ‘‘smelting and pressing of ferrous

metals’’, ‘‘manufacture of non-metallic mineral products’’,

and ‘‘manufacture of raw chemical materials and chemical

products’’. The sub-areas are delineated following the juris-

dictional scopes (see Fig. 1). Hebei is divided into 11 areas

according to the jurisdiction of the 10 prefectures and the

capital city; Beijing is divided into 1 urban area (covering 6

districts) and 10 peripheral districts/counties; and Tianjin is

divided into 1 urban area (covering 6 districts) and 12

peripheral districts/counties. Six emission reduction scenari-

os are designed (Table 2).

The Community Multi-scale Air Quality (CMAQ) modeling

system is used to simulate the fate and transport of SO2 in the

study region. CMAQ is an open-source model capable of

modeling tropospheric ozone, fine particles, acid deposition,

and visibility degradation, developed by USEPA.3 The fifth-

generation Pennsylvania State University/National Centre for

Atmospheric Research Mesoscale Model (Grell et al., 1994) is

used to simulate the meteorological fields to drive CMAQ. The

gridded and speciated hourly emission inputs for CMAQ are

prepared using the Sparse Matrix Operator Kernel Emissions

model (Houyoux et al., 2000).

As SO2 is mainly emitted from sources burning fossil fuels

and all the year round daily SO2 concentrations during the

heating season frequently exceed the health-based standard,

we focus on the heating season in doing our simulation. We

choose December 2006 to conduct the simulation. In November,

heat supply gradually starts, while in January and February,

3 http://www.epa.gov/asmdnerl/CMAQ/index.html.

people celebrate the Chinese Lunar New Year. The model is

validated using observed data at Shangdianzi where a World

Meteorological Organization Global Atmosphere Watch moni-

toring station is located. Shangdianzi, about 100 km to the

northeast of Beijing urban area, is located in Hebei province and

Fig. 3 – Comparison of simulated and measured hourly SO2

concentrations.

Fig. 4 – The SO2 concentrations under Scenario 1 (baseline

scenario).

e n v i r o n m e n t a l s c i e n c e & p o l i c y 2 5 ( 2 0 1 3 ) 1 6 7 – 1 7 5 171

regarded as a clean background area in northern China. Hourly

SO2 concentrations are measured at this station and used to

validate the modeling results. It can be seen that the modeling

results and the measured data agree well (Fig. 3).

We would like to understand how the reduction of SO2

emissions in major sectors would impact SO2 concentrations

in the different areas within the Beijing–Tianjin–Hebei region.

Ideally, we would like to conduct a brutal force simulation on

the impact of the reduction of different amounts of SO2 in each

sector. However, it is computationally costly to conduct such

an undertaking. Instead, we designed six scenarios on SO2

emission reductions and then use linear extrapolation to

derive the impact of other SO2 emissions reduction scenarios

based on the results of these six scenarios. The simulated

results are shown in Figs. 4 and 5.

3.3. Estimating health impact

The adverse health and ecological effects associated with SO2

pollution are well-documented (e.g., Ware et al., 1981;

Moolgavkar et al., 1995; Likens et al., 1996; Sunyer et al.,

2003; Larssen et al., 2006). Exposure to SO2 may cause

respiratory diseases and lead to premature death. High

concentrations of SO2 and particulate matter with SO42�, a

product of SO2’s atmospheric reaction, being one of its major

components are found to contribute significantly to the

Fig. 5 – The degree of decrease in SO2 concentrations under Scenarios 2–6.

Table 3 – Intake fraction avoided per tonne of SO2

emissions reduced in the major SO2 emission sectorsand the ‘‘other’’ sector (Scenario 6).

Sectors iFa

Production and distribution of electric power

and heat power

4.73 � 10�7

Smelting and pressing of ferrous metals 6.46 � 10�7

Manufacture of non-metallic mineral products 7.62 � 10�7

Manufacture of raw chemical materials and

chemical products

4.36 � 10�7

Others 9.34 � 10�7

4 Guojia huanjing baohu shi er wu guihua [the National 12th Five-Year Plan for Environmental Protection], prepared by the Ministryof Environmental Protection, released by the State Council onDecember 15, 2011.

e n v i r o n m e n t a l s c i e n c e & p o l i c y 2 5 ( 2 0 1 3 ) 1 6 7 – 1 7 5172

elevated episodic respiratory morbidity and mortality in the

London fog in 1952 (Bell and Davis, 2001). A significant

association between the concentration of SO2 and the daily

mortality through the year was found in Beijing in 1989, and

the mortality risk was estimated to increase by 11% as the

concentration of SO2 doubles (Xu et al., 1994). Strong

association between SO2 exposure and respiratory ailments

has been found in such big cities as Shenyang and Chongqing

as well. SO2 plays a significant role in the formation of

regional haze which haunts almost all the city-clusters in

China, especially in winter. Besides the esthetic and health

impact, regional haze incurs enormous cost to the aviation

industry and the ground transportation sector. SO2 is also one

of the important precursors of acid rain, which can affect fish

populations, crop yields, and forests growth and survival, and

corrode buildings (Larssen et al., 1999, 2006). For most of the

ground-level air pollutants, people’s attention is more on

their health impact; while for SO2 pollution, the ecological

risk incurred by acid rain is of particular concern. In the

specific case of the Beijing–Tianjin–Hebei region, acid rain is

not severe because alkaline soil dust blown by wind helps to

neutralize the acidity of the emissions (Larssen et al., 1999).

Thus, we focus on the health risks associated with SO2

exposure.

In estimating health risks, we use the concept of intake

fraction to estimate the marginal benefit per tonne of SO2

emissions reduced (Eq. (1)) in the major sectors. Intake fraction

is defined as the incremental intake per unit of pollutant

release from a source or a category of sources (Bennett et al.,

2002). We slightly modify it to be the intake avoided per unit of

pollutant reduced for our purpose (Eq. (1)).

iFa ¼PN

k¼1 POPk � Ck � RER

(1)

where iFa denotes the fraction of intake avoided, k is the index

of sub-areas in the study region, N is the total number of sub-

areas in the region, POPk is the size of population in sub-area k,

Ck is the change in SO2 concentration in sub-area k, R is the

average breathing rate of an adult, and ER is the emission

reduced during a given time. In our research, the total number

of sub-areas is 35 (see the first paragraph in Section 3.2), the

sizes of the population in the 35 sub-areas are obtained from

provincial statistical yearbooks, the changes in SO2 concen-

tration in each of the 35 sub-areas are obtained by using

simulation, R is set to be 20 m3/days, and ER is the emission

reduction in December in each of the major sectors following

the six emission reduction scenarios set in the modeling part.

Scenario 1 is the baseline scenario, i.e., no emission reduction.

Here, we present the estimated intake avoided per tonne of

SO2 emissions in Scenarios 2–6, which represents the risks

avoided per tonne of SO2 emission reduction in the four major

sectors and the ‘‘other’’ sector (Scenario 6). The results are

shown in Table 3.

We use intake instead of health outcomes (e.g., respiratory

disease) to indicate the degree of health risks, as the major

purpose of our research is to estimate the marginal contribu-

tion to health risks by reducing one unit of SO2 emissions from

the different sectors and then to inform pollutant control

responsibility assignment and pollution control option priori-

tization. If we want to estimate the benefit of air pollution

control policies, then it is necessarily to estimate the number

of cases of the different health outcomes.

4. Conclusions and implications

In the previous SO2 control practices in China, the impacts per

tonne of SO2 from the different sectors are implicitly treated as

the same. As indicated in our case study, the risks reduced per

tonne of SO2 emission reduction in the different sectors are

quite different. The intake fraction avoided per tonne of SO2

emissions reduction in the sectors of ‘‘production and distribu-

tion of electric power and heat power’’, ‘‘smelting and pressing

of ferrous metals’’, ‘‘manufacture of non-metallic mineral

products’’, ‘‘manufacture of raw chemical materials and

chemical products’’ and ‘‘the aggregate of the other sectors’’

varies greatly. This means it will help improve the efficiency in

resource utilization by using a risk-based approach to assign

pollutant control responsibilities and prioritize pollutant

control options. The case study also demonstrates the

technically feasible to apply a risk-based approach to address

regional air pollution problems in a Chinese setting, which is of

great practical value for the following reasons.

Firstly, regional air pollution in China has become an issue of

great concern (Shao et al., 2006; Chan and Yao, 2008), while the

existing jurisdiction-based air quality management mecha-

nism is inadequate in addressing regional air pollution. There is

a strong political will in utilizing a regional mechanism to

manage air quality in China. As economy grows and urbaniza-

tion progresses, 28 city-clusters (city-cluster and region are used

interchangeably here) have emerged in China (Fang et al., 2005).

In these city-clusters, the economic activities are vibrant, the

populations are dense, and consequently the environmental

stresses are high. The air quality management programs in

China are designed and implemented on a jurisdictional basis,

while air pollutants (e.g., SO2, PM and O3) travel across

administrative borders (Peking University, 2007; DiGiovanni

and Fellin, 2005; Guo et al., 2009; Yan et al., 2005). Regional

concerted efforts are needed to address regional air pollution

problems. Being aware of this, the Chinese government in its

National 12th Five-Year Plan for Environmental Protection

(2010–2015)4 lists preventing and controlling air pollution on an

e n v i r o n m e n t a l s c i e n c e & p o l i c y 2 5 ( 2 0 1 3 ) 1 6 7 – 1 7 5 173

air-shed or regional basis as one of the key programs to be

carried out.

Secondly, the regional social-economic development dis-

parity legitimates a regional (instead of national) effort in air

quality management as well. In the vast land of China, the

eastern coastal provinces are relatively developed and the

central and western provinces are less developed. For

instance, in 2009, the per capita gross municipal product of

Shanghai (a coastal city) reaches 79,000 Chinese Yuan which is

the highest in China while the per capita gross provincial

product of Guizhou (a province in southwest China) is 10,300

Chinese Yuan which is the lowest in China (National Bureau of

Statistics, 2010a). This developmental disparity has been

taken into consideration in assigning pollution control

responsibilities among the provinces in China’s 11th Five-

Year Plan. One of the compulsory targets of the 11th Five-Year

Plan is to cut national SO2 emissions from the 2005 level by 10%

till the end of 2010. This target is then allotted to provinces

disproportionally considering the status of economic devel-

opment, the gravity of local environmental pollution and

historical provincial SO2 emissions, with a reduction degree

ranging from 0.0% (Tibet) to 25.9% (Shanghai) (SEPA and NDRC,

2007). Thus, practically, it makes more sense to design risk-

based air quality management schemes at regional levels than

at a national level, as new polices building upon the current

system are easily get implemented.

Thirdly, the situation of lacking the data to develop risk-

based air quality management strategies in China has been

greatly alleviated, at least in relatively developed regions.

Driven by the deterioration of the environment, the increase in

the general public’s environmental awareness and the growth

of the national wealth, a substantial amount of resources has

been allocated to address environmental problems in China

over the past ten years (MEP, 2000–2010). Many pollutant

emission and concentration data have been accumulated,

especially in mega-cities such as Beijing, Shanghai and

Guangzhou. Catalyzed by such mega-events as the 2008

Beijing Summer Olympics, Shanghai Expo 2010, and Guangz-

hou 2010 Asian Games, quite a few big projects have been

conducted to identify air pollutant emission sources, simulate

the fate and transport of air pollutants, and design pollution

control strategies for the host cities and their immediate

vicinities. Nationally, taking 2007 as the baseline year, the first

national pollution survey was conducted in China in 2008. The

aggregated 2007 pollution information was released in 2010

jointly by Ministry of Environmental Protection, National

Bureau of Statistics of China, and Ministry of Agriculture (MEP

et al., 2010), while the detailed pollution inventory is not

publicly available yet. It is expected that more and more

environmental data will be made publicly available in the near

future as a result of the demand for environmental informa-

tion transparency from the public. In this regard, it becomes

more feasible for governmental agencies and research

institutes to conduct risk-based air quality research to support

environmental decision making.

Fourthly, the health risks associated with one unit

pollutant emissions from the different sources could be quite

different considering the relationship between emissions and

health risks (Fann et al., 2009; Levy et al., 2009). The

meteorological factors, the health status of the individuals

exposed, the size and location of the emissions sources, the

height of the stacks, and the proximity of the population all

affect the strength of such a relationship. Facing the large

number of sources, it is computationally tedious and

administratively burdensome to estimate the health risks

posed by emissions from each of them. Often, the sources are

grouped by sector and then sector-level pollutant emissions

and health risks are estimated (e.g., Ho and Nielsen, 2007;

Zhou et al., 2010). Of course, this implies that sources within a

sector are treated equally regarding their impact per unit of

emissions. Comparing with a risk-based pollution control

strategy on individual sources, a sector-level emission control

strategy has less impact on the competitiveness of enterprises

within a sector and thus less impedance from enterprises.

Finally, different from most of the city-clusters in the

developed world, where the primary pollutants (e.g., SO2) are

substantially reduced and the secondary pollutants (e.g., PM2.5

and O3) are the major policy targets, the city-clusters in China

face both severe primary and secondary air pollution. It is

well-recognized that a mix of policies is needed to address the

complex air pollution problems in city-clusters in China. We

choose SO2 to demonstrate how a risk-based approach can be

used to improve the efficiency in resource utilization by

guiding the assignment of pollutant control responsibility and

the design of pollutant control strategies, and would like to

study PM2.5 and O3 with a similar approach in our ensuing

work.

It should be noted that we use the emission inventory of

2006 to demonstrate the feasibility of using a risk-based

approach to address regional primary air pollution problems.

Since then, five years has passed by and the 11th five year plan

has been fulfilled, during which, the SO2 emissions at a

national level and in our study region have been decreased by

14% and about 15%, respectively. Thus great care should be

taken in directly using the results of this research to guide

policy making. Nevertheless, the argument made and case

study conducted is expected to be a convincing advocacy to

the adoption of a risk-based approach to address regional

primary air pollution problems.

A risk-based approach helps improve the efficiency in

utilizing societal resources, but it is not a panacea. In

addressing regional air quality problems in China, a set of

policies are still needed, which include, but not limited to,

setting compulsory emission reduction targets by fully

considering the regional environmental capacity, avoiding

hot spots by continuing the restriction of constructing high-

polluting enterprises in designated areas, and paying particu-

lar attention to the area sources.

Acknowledgements

The authors would like to thank Desheng Huang, Yana Jin,

Xunzhou Ma, Quan Mu, Wei Wan, Dan Wu, Xuxuan Xie and

Xiuli Zhang for helping assigning the individual emission

sources to sectors, and Teng Nie for contributing to the CMAQ

simulation. The authors would also like to thank Yuesi Wang

from the Institute of Atmospheric Physics, Chinese Academy

of Sciences, for providing daily SO2 monitoring data covering

the study region from which we realized that the daily SO2

e n v i r o n m e n t a l s c i e n c e & p o l i c y 2 5 ( 2 0 1 3 ) 1 6 7 – 1 7 5174

concentrations during the heating season frequently exceeds

the health-based national air quality standards. The authors

are indebted to Weili Lin for sharing the monitoring data at

Shangdianzi which we used to validate our simulated results.

The research is supported by Beijing Municipal Commission of

Science and Technology under Grant No. D09040903670905,

Economy and Environment Program for Southeast Asia, and

the Public Welfare Projects for Environmental Protection

under Grant Nos. 200909003 and 201009002.

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Jianhua Xu is an environmental and energy associate professor atDepartment of Environmental Management, Peking University,and an adjunct research fellow at School of Public Policy andManagement, Tsinghua University. She got her PhD in engineeringand public policy from Carnegie Mellon University. Her researchinterest is in qualitative and quantitative decision analysis andrisk analysis related to environmental and energy policy.

Xuesong Wang is an associate professor at Department of Envi-ronmental Sciences, Peking University. He got his PhD degree inenvironmental science from Peking University. His research inter-ests include urban and regional air pollution modeling and as-sessment, atmospheric chemistry and transport.

Shiqiu Zhang is an environmental economic professor at Depart-ment of Environmental Management, Peking University. She isalso the Director of Institute of Environment and Economy, PKU.Her research interest is in the field of environmental economics,environmental management and policy.