Ten cities cross-sectional questionnaire survey of children asthma and other allergies in China

Abstract

Asthma, rhinitis and eczema (allergic or non-allergic) have increased throughout the world during the last decades, especially among children. Changes in the indoor environment are suspected to be important causes. China has experienced a dramatic change in indoor environmental exposures during the past two decades. However, such changes and their associations with children’s asthma and other health aspects have not been thoroughly studied. China, Children, Homes, Health (CCHH), Phase I, is a cross-sectional questionnaire survey of 48219 children 1–8 years old in 10 Chinese cities during 2010–2012. The questionnaire included the International Study of Asthma and Allergies in Childhood (ISAAC) core health questions and additional questions regarding housing, life habits and outdoor environment. In health analyses, children aged 3–6 years old were included. The prevalences of doctor diagnosed asthma varied from 1.7% to 9.8% (mean 6.8%), a large increase from 0.91% in 1999 and 1.50% in 2000. The prevalence of wheeze, rhinitis and atopic eczema (last 12 months) varied from 13.9% to 23.7%, 24.0% to 50.8% and 4.8% to 15.8%, respectively. Taiyuan had the lowest prevalences of all illnesses and Shanghai the highest, except for wheezewhere the highest value was for Urumqi. The analyses for the results showed that: (1) There is no obvious association between the diseases and ambient PM10 concentration; (2) The association between the diseases and economic status indexed by GDP (Gross Domestic Production) per capita needs further study; (3) Prevalences are higher in humid climates with hot summers and cold winters but do not have centrally heated buildings.

Full text

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*Corresponding authors (email: sundellcc@gmail.com; zhangyp@tsinghua.edu.cn; baizhanli@cqu.edu.cn)
Review
SPECIAL TOPIC doi: 10.1007/s11434-013-5914-z
China, Children, Homes, Health
Ten cities cross-sectional questionnaire survey of children asthma
and other allergies in China
ZHANG YinPing1*, LI BaiZhan2*, HUANG Chen3, YANG Xu4, QIAN Hua5, DENG QiHong6,
ZHAO ZhuoHui7, LI AnGui8, ZHAO JiaNing9, ZHANG Xin10, QU Fang1, HU Yu3, YANG Qin2,
WANG Juan2, ZHANG Ming4, WANG Fang9, ZHENG XiaoHong5, LU Chan6, LIU ZhiJian8,
SUN YueXia11, MO JinHan1, ZHAO YiLi5, LIU Wei3, WANG TingTing12, NORBÄCK Dan13,
BORNEHAG Carl-Gustaf14 & SUNDELL Jan1*
1 Department of Building Science, Tsinghua University, Beijing 100084, China;
2 Key Laboratory of Three Gorges Reservoir Region’s Eco-Environment, Chongqing University, Chongqing 400030, China;
3 School of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai 200093, China;
4 College of Life Sciences, Central China Normal University, Wuhan 430079, China;
5 School of Energy & Environment, Southeast University, Nanjing 210096, China;
6 School of Energy Science and Engineering, Central South University, Changsha 410083, China;
7 School of Public Health, Fudan University, Shanghai 200032, China;
8 School of Environmental and Municipal Engineering, Xi’an University of Architecture and Technology, Xi’an 710055, China;
9 School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090, China;
10 Research Center for Environmental Science and Engineering, Shanxi University, Taiyuan 030006, China;
11 School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China;
12 School of Public Health, Xinjiang Medical University, Urumqi 830011, China;
13 Department of Occupational and Environmental Medicine, University Hospital and Uppsala University, Uppsala SE-751, Sweden;
14 Public Health Sciences, Karlstad University, SP Technical Research Institute of Sweden, Uppsala SE-751, Sweden
Received February 20, 2013; accepted May 15, 2013
Asthma, rhinitis and eczema (allergic or non-allergic) have increased throughout the world during the last decades, especially
among children. Changes in the indoor environment are suspected to be important causes. China has experienced a dramatic
change in indoor environmental exposures during the past two decades. However, such changes and their associations with chil-
dren’s asthma and other health aspects have not been thoroughly studied. China, Children, Homes, Health (CCHH), Phase I, is a
cross-sectional questionnaire survey of 48219 children 1–8 years old in 10 Chinese cities during 2010–2012. The questionnaire
included the International Study of Asthma and Allergies in Childhood (ISAAC) core health questions and additional questions
regarding housing, life habits and outdoor environment. In health analyses, children aged 3–6 years old were included. The preva-
lences of doctor diagnosed asthma varied from 1.7% to 9.8% (mean 6.8%), a large increase from 0.91% in 1999 and 1.50% in
2000. The prevalence of wheeze, rhinitis and atopic eczema (last 12 months) varied from 13.9% to 23.7%, 24.0% to 50.8% and
4.8% to 15.8%, respectively. Taiyuan had the lowest prevalences of all illnesses and Shanghai the highest, except for wheeze-
where the highest value was for Urumqi. The analyses for the results showed that: (1) There is no obvious association between the
diseases and ambient PM10 concentration; (2) The association between the diseases and economic status indexed by GDP (Gross
Domestic Production) per capita needs further study; (3) Prevalences are higher in humid climates with hot summers and cold
winters but do not have centrally heated buildings.
environmental health, indoor air quality, homes, exposure, urbanization
Citation: Zhang Y P, Li B Z, Huang C, et al. Ten cities cross-sectional questionnaire survey of children asthma and other allergies in China. Chin Sci Bull,
doi: 10.1007/s11434-013-5914-z

2 Zhang Y P, et al. Chin Sci Bull January (2013) Vol.58 No.1
Asthma prevalence has increased worldwide during the last
decades [1–7]. The magnitude of prevalence has generally
been smaller in low-income countries or regions, but the
rates of increase may be accelerating [1,4,5]. The Interna-
tional Study of Asthma and Allergies in Childhood (ISAAC)
reported that the highest prevalences of asthma in children
aged 6–7 years were in the UK, Australia, New Zealand and
Ireland, while the lowest prevalences were in Indonesia,
Albania, Romania, Georgia and Greece [1]. In many parts
of the world, a large fraction of children have or have had
asthma, wheeze, rhinitis or eczema [1,2]. The cost, family
burden and impaired life quality due to asthma and allergies
are severe public health problems. It is anticipated that there
will be about 300 million people suffering from asthma by
2025 [6].
Neither genetic factors [7], outdoor environmental pollu-
tion [8–12], racial factors [13], nor socio-economic status
[14] can wholly explain this dramatic increase. People
spend a large part of their time indoors and pre-school chil-
dren spend a longer time in homes compared with adults
[15,16]. The indoor environment, especially in homes, has
been implicated as having an important role in inducing
and/or exacerbating asthma and allergies among children
[17–25].
The ISAAC project was started in 1990 in Germany and
New Zealand with the aim of quantifying the prevalence
and characterizing the severity of asthma and allergies
worldwide [26]. Studies had been conducted in 236 centers
in 98 countries [27] before 2009. However, ISAAC studies
lack data on indoor environmental and building related risk
factors. The idea to study “asthma and the home environ-
ment” was initiated in Sweden because of the Allergy In-
quiry (a 1987–1989 governmental inquiry) to identify caus-
es of the dramatic increase of allergic children in Sweden.
The Swedish study, “Dampness in Buildings and Health”
(DBH) was started in 2000 with the aim of characterizing
associations between building dampness and asthma and
allergies among children. Its hypothesis and background
were based on scientific state-of-the-art reviews [17,28–33].
Questionnaires and experimental protocols were designed
for a multidisciplinary study involving environmental sci-
ence, engineering, chemistry and microbiology in addition
to medicine and public health. By 2010, studies built on the
platform of the Swedish study had been carried out in sev-
eral countries [19,22,34–38].
The prevalences of asthma and allergies have, in some
western countries, recently stabilized or even decreased
[39,40]. These changing trends coincide with the currently
slower rate of change in indoor environment exposures in
these countries. China, a developing country, is experienc-
ing rapid and dramatic changes in indoor environment ex-
posures due to its rapid modernization and urbanization.
National surveys of asthma in Chinese children aged 0–14
years in 1990 and 2000 by the Childhood Asthma Collabo-
rative Group of China [41] as well as a number of other
studies indicate that asthma and allergies have increased in
China [4,7,42–51]. However, information about indoor ex-
posure has been included to only a small extent and in only
a few studies [52,53].
In September 2010, we launched the project China, Chil-
dren, Homes, Health (CCHH) in 10 major cities in China.
Ten universities are involved in CCHH. There are two
phases: Phase I is a cross-sectional questionnaire study of
the prevalence of children’s asthma, allergies and airway
infections, and home environmental exposures (2010.11–
2012.4) (See Appendix A, Questionnaire for CCHH); Phase
II will be a case-control study with measurements of pollu-
tants in sampled air, dust and urine (2012.11–). The objec-
tives of the CCHH research project are:
(1) to investigate the prevalences of asthma, allergies and
airway infections in major Chinese cities with different cli-
mates, outdoor air quality, and economic level;
(2) to investigate and compare indoor environmental as-
pects of sick and healthy children’s homes;
(3) to study associations between children’s health and
indoor environmental factors;
(4) to compare risk and protective factors in different
cities of China;
(5) to compare findings from CCHH with those of other
countries and regions outside of mainland China;
(6) to provide epidemiological data as a foundation for
the prevention of asthma and allergies among children in
China.
This paper reports some basic data from all cities and
some historic trends in the prevalences of asthma, allergies
and the percentage of children who have had one or more
episodes of pneumonia.
1 Subjects and methods
1.1 Sites studied and children selected
The CCHH study was carried out in 10 cities in different
geographic regions of China with different per capita eco-
nomic statuses and outdoor environmental pollution levels
(Table 1 and Figure 1). Every city included urban areas.
Some cities included rural or suburban areas. Kindergartens
or daycare centers or primary schools were randomly se-
lected in each city.
1.2 Questionnaire design and pilot study
CCHH research used questions from the ISAAC study [56]
about children’s asthma, and allergies. Questions from the
Swedish DBH study about the home environments [19]
were adapted so as to be relevant to Chinese home charac-
teristics [57]. The questionnaire was tested in a pilot study
of 100 children in Chongqing in April 2010, and thereafter
adjusted to improve readability. For details about question-
naire design, see articles for specific CCHH cities [58–68].

Zhang Y P, et al. Chin Sci Bull January (2013) Vol.58 No.1 3
Table 1 Economic status, geography, climate and PM10 concentration of the investigated cities in CCHH studies
Cities
(from north to south)
Economic status
(Income, per capita GDP, kRMB)a) Dry/humid [54] Type of climate [55]
Annual mean concentration
of PM10 (μg/m3) b)
2001 2010
Harbin 37.0 Sub-humid Severe cold 134.7 102.6
Urumqi 44.9 Dry Severe cold 203.6 139.1
Beijing 75.9 Sub-humid Cold 175.2 122.3
Taiyuan 44.3 Sub-humid Cold 203.7 89.2
Xi’an 38.3 Sub-humid Cold 156.5 126.1
Nanjing 63.7 Humid Hot summer and cold winter 140.0 112.7
Shanghai 76.1 Humid Hot summer and cold winter 101.7 79.3
Wuhan 59.0 Humid Hot summer and cold winter 150.4 107.0
Chongqing 27.6 Humid Hot summer and cold winter 141.5 102.5
Changsha 66.4 Humid Hot summer and cold winter 181.0 83.6
a) From the annual report of each city, using 2010 data (except Taiyuan, 2009); b)from the Ministry of Environmental Protection of China.
Figure 1 Prevalences (%) of rhinitis, wheeze, and atopic eczema in the last 12 months and pneumonia (at least one episode), for children 3–6 years old in
all cities except Taiyuan (3–5) and Wuhan (5–6) years old.
1.3 Procedure for Phase I study
The procedure for the questionnaire survey was as follows:
We first contacted the director of each kindergarten. After
he or she agreed on participation, questionnaires were dis-
tributed by the responsible teachers in each class to the
children’s parents or legal guardians. Finally, parents re-
turned the questionnaires to the teachers, and we collected
the completed questionnaires from the teachers.
The data were input and statistically analyzed by SPSS
software.
2 Results
In the CCHH investigation Phase I, parents of 48219 chil-
dren aged 1–8 responded to the questionnaire, yielding a
76.9% average response rate. Table 2 presents detailed in-
formation on children’s ages, numbers of respondents, and
response rates. Non-respondents were tracked by short
questionnaires in Chongqing. A number of 300 children
were randomly selected from those who had not responded
in the cross-sectional study and 206 responded. The five

4 Zhang Y P, et al. Chin Sci Bull January (2013) Vol.58 No.1
Table 2 Number of respwondents and response rate in investigated cities
Cities Age
(years)
Number of
respondents
Response
rate (%)
Harbin 2–8 2506 64.1
Urumqi 2–7 4618 81.7
Beijing 1–8 5876 65.0
Shanghai 1–8 15266 85.3
Nanjing 1–8 4014 65.7
Xi’an 1–8 2020 83.5
Taiyuan 1–6 3700 82.2
Wuhan 1–8 2193 91.4
Changsha 1–8 2727 59.0
Chongqing 1–8 5299 74.5
questions in the short questionnaires asked about home site
(location), gender, wheezing in the last 12 months, visible
damp stains and family smoking. There were no significant
differences between responses to the short questionnaire,
and responses to the same questions in the long question-
naire (see Table S1).
Distributions of gender, age and family allergic histories
among investigated children in 10 cities are shown in Table
3. As the number of children in age groups 1, 2, 7 and 8
were small in most cities, further analyses of health out-
comes were for children 3–6 years of age, except for Tai-
yuan (3–5 years of age) and Wuhan (5–6 years of age). Ta-
ble 4 shows the age-adjusted prevalences of illnesses (3–6
years, except Taiyuan (3–5) and Wuhan (5–6)). Prevalences
for the last 12 month of wheeze, rhinitis, and eczema, as well
as the percentages of children who had had one or more life-
time episodes of pneumonia, are shown in Figure 1.
Asthma was determined as a “yes” reply to the question
“Has your child ever been diagnosed with asthma by a doc-
tor?”. In Figure 2, the findings of the CCHH ten city study
in 2010–2011 are compared with mean prevalences among
0–14 year old children in 1990 and 2000 [41]. All preva-
lences are normalized against 1990 data. Figure 3 shows the
same comparison but with actual (non-normalized) data.
Prevalences of doctor-diagnosed asthma have increased
faster during the last ten years than during the decade from
1990 to 2000. Urumqi, Wuhan, Beijing and Shanghai had
the most rapid increase in the last decade.
Figures 4 and 5 show ecological comparisons. Southern
cities, humid all year but cold in winter and without heating,
Table 3 Percentages by gender, allergy in the family and children’s ages in CCHH Phase I citiesa)
City name Gender (%) Allergy in family (%) Age (%)
Male Female Yes 1 2 3 4 5 6 7 8
Harbin 50.3 49.7 13.3 0 1.8 10.3 21.2 23.0 27.3 14.4 2.0
Urumqi 53.6 46.4 19.8 0 2.1 24.3 36.0 30.4 6.9 0.1 0
Beijing 52.4 47.6 23.4 0.5 2.2 24.1 28.7 26.3 16.3 1.3 0.6
Shanghai 50.9 49.1 19.4 0.2 0.1 5.0 37.2 29.4 22.6 5.2 0.3
Nanjing 51.2 48.8 15.8 0.1 1.0 11.4 23.6 25.2 24.9 12.0 1.8
Xi’an 53.3 46.7 9.2 0.1 1.4 19.7 28.1 28.6 19.7 2.2 0.2
Taiyuan 52.3 47.7 11.5 0.2 4.5 30.4 36.4 26.8 1.7 0.0 0.0
Wuhan 52.7 47.3 16.9 0.5 0.1 1.4 3.6 4.8 10.3 32.2 47.1
Changsha 53.3 46.7 15.4 0.2 2.8 24.5 34.2 31.2 6.6 0.4 0.1
Chongqing 51.3 48.7 11.1 0.3 2.4 20.0 32.4 29.6 14.1 1.1 0.1
a) Age 1 means the children’s age ≤ 1, age 2 means the children’s age > 1 and ≤ 2, and so on.
Table 4 Age adjusted prevalences of symptoms and other illnesses in children 3–6 years old
Harbin Urumqi Beijing Shanghai
Nanjing Xi’an
Taiyuane) Wuhanf) Changsha
Chongqing
Wheeze ever 19.6 35.3 22.3 27.9 23.4 20.2
21.7 31.2 27.0 26.7
Wheeze last 12 months 15.3 23.7 16.7 21.6 17.9 13.9
14.1 19.0 19.3 20.2
Dry cough last 12 months 11.7 11.9 19.4 19.7 18.5 15.0
7.9 18.4 16.0 18.4
Dr.diagnosed asthma 2.9 3.9 6.3 9.8 8.8 3.0
1.7 7.4 6.9 8.2
Rhinitis ever 55.3 48.9 57.7 55.2 54.6 56.5
38.6 58.7 54.2 51.6
Rhinitis last 12 months 42.0 43.7 45.5 43.7 42.8 38.7
24.0 50.8 41.2 38.3
Rhinitis on pet exposure 1.0 4.3 3.3 4.6 2.0 2.1
2.5 9.3 2.0 2.7
Rhinitis on pollen/grass exposure 1.9 6.3 6.9 7.6 8.0 6.4
1.1 19.4 11.5 3.6
Dr. diagnosed Rhinitis 2.2 9.8 7.9 11.6 8.8 3.7
2.7 23.9 8.0 6.2
Eczema evera) 33.1 15.3 34.7 23.4 28.4 29.0
13.6 26.0 29.9 30.4
Eczema last 12 monthsb) 12.2 13.3 15.8 13.9 10.7 8.2
4.8 8.4 9.7 12.9
Croup 3.2 6.3 4.3 7.6 4.2 4.5
4.0 5.8 5.9 6.3
Pneumonia 30.2 41.7 26.9 33.2 27.1 28.2
27.8 25.5 38.1 31.3
Common cold ≥6 times last 12 months 6.0 7.6 9.5 8.5 9.9 7.1
4.7 6.1 7.9 18.1
Ear infectionc) 8.3 11.9 14.9 10.5 7.8 7.7
9.0 16.2 7.7 7.8
Food allergyd) 22.2 16.4 23.9 19.4 20.5 12.9
12.7 17.0 17.6 16.9
a) Has your child ever had an itchy rash (eczema), which was coming and going for at least 6 months? b) In the last 12 months, has your child had itchy
skin rash? c) Has your child ever had ear infections? d) Has your child ever developed itchy skin, rash, diarrhea, swollen lips, or swollen eyes as a result of
eating the foods below? e) Age adjusted for 3–5 years old children; f) Age adjusted for 5–6 years old children.

Zhang Y P, et al. Chin Sci Bull January (2013) Vol.58 No.1 5
Figure 2 Prevalences of children’s asthma normalized for 1990.
have an asthma prevalence >6.9%. The dry northern cities
which do have heating during winter, have an asthma prev-
alence <4% with the exception of Beijing, with the asthma
prevalence of 6.3%. There are no associations in ecological
analyses between wheeze, rhinitis, eczema and pneumonia
and climate, GDP/capita or ambient PM10. From Table 1 it
is also seen that ambient PM10 is reported to have decreased
in all cities during the last 10 years, the years that asthma
has increased more rapidly. Figure 5 shows an association
between doctor-diagnosed asthma and GDP/capita, however
the result is distorted by the outlier Chongqing.
Data regarding general characteristics of the study popu-
lation, housing characteristics, and dampness, and odors in
homes are given in Tables S2–S4.
3 Discussion
The CCHH survey covers 10 major cities in China with
different climates, geographies and per capita economic
status. In total, there are 48219 children (and homes), of
whom 43591 are 3–6 years old, and included in the analyses
of health outcomes. The mean response rate, 76%, is rea-
sonably high. This study is subject to the limitations inher-
ent in any cross-sectional survey. Data used for analyses
were collected retrospectively and relied on parental reports;
our findings could therefore be subject to recall bias. How-
ever, the questions on outcomes were validated in the
ISAAC study[69], and questions on indoor exposures used
in the present study have been validated in previous stud-
ies[70,71]. Non-respondents were reached by a short survey
in Chongqing. There were no significant differences in the
prevalences of wheezing in the last 12 months between
responders and non-responders to the long questionnaire,
which indicates that neither selection nor non-response bi-
ases are likely present. The possible influence of bias on
Figure 3 National trends for children’s asthma in the cities investigated (3–6 years old, except for Taiyuan (3–5) and Wuhan (5–6) compared with the
prevalence of 0–14 years old children 1900, 2000 [41]).

6 Zhang Y P, et al. Chin Sci Bull January (2013) Vol.58 No.1
Figure 4 Correlation between outdoor PM10 concentration in 2010 and
prevalence of asthma in 2011.
Figure 5 Correlation between GDP per capita in 2010 and prevalence of
asthma in 2011.
specific topics is discussed in the articles from each city
[58–68].
The prevalences of doctor-diagnosed asthma in CCHH
cities varied from 1.7% to 9.8% (mean 6.8%). This repre-
sents a great increase from 0.91% in 1999 (287329 children)
and 1.50% in 2000 (299193 children in 27 cities of China).
The prevalences of wheeze, rhinitis and eczema (last 12
month) varied from 13.9% to 23.7%, 24% to 50.8% and
4.8% to 15.8% respectively. For all symptoms, Taiyuan had
the lowest prevalences, whereas the more developed eastern
cities had the highest prevalences, with the exception of
Urumqi, which had the highest prevalence of wheeze. Eco-
logical analyses show no obvious association between dis-
eases and ambient air pollution (PM10), or the economic
status as indexed by GDP (Gross Domestic Production) per
capita, but suggest that prevalences were higher in humid
climates where summers are hot, winters cold, and there is
no heating. In comparison with earlier studies, the prevalenc-
es of parentally reported wheeze, rhinitis and eczema, and
parentally reported doctor-diagnosed asthma were high, indi-
cating increased prevalences of these symptoms and diseases.
Other recent studies [4,46–51] confirm these findings.
The comparisons in Figures 2 and 3 between prevalences
of doctor-diagnosed asthma in 1990, 2000 and 2011 are
important. Because the samples of children 1–2 and 7–8
years old were small, the present CCHH study reports
health outcomes for children 3–6 years old. The national
studies of 1990 and 2000 [41] surveyed children 0–14 years
old, so that a direct comparison is not possible. Nonetheless,
the CCHH survey of 10 cities shows that children’s asthma
has increased. Moreover, the increase has accelerated since
2000 (Figure 2).
The prevalences of wheeze, rhinitis and atopic eczema
are not as different between cities as the prevalences of
doctor-diagnosed asthma (Figures 1 and 3). The difference
in prevalences between parentally reported doctor-diag-
nosed asthma (Figure 3) and parentally reported symptoms
in different regions maybe due to regional differences in
health care systems. Comparison between Figure 1 (parental
reported wheeze) and Figure 3 (parental reported doctor-
diagnosed asthma) may reflect differences in how likely it is
that a child is taken to a clinic for a diagnosis of asthma as
well as for rhinitis.
The reported percentage of children who have had at
least one doctor-diagnosed episode of pneumonia is high
(25.5%–41.7%), especially given that urban pneumonia
rates are generally lower than those of rural areas, where
there is extensive exposure to smoke from burning of bio-
mass [72]. The children in this study are mainly living in
new modern apartments, exposed to environmental tobacco
smoke, indoor molds and dampness, with lower air ex-
change rate (see articles from Nanjing[65], and Urumqi [59]
for further discussion).
4 Conclusions
Prevalences of “allergic” diseases and symptoms have in-
creased in large Chinese cities. More than half of the 3–6
year old children surveyed have had at least one manifesta-
tion of wheeze, rhinitis or eczema, and more than one-fourth
of children have had at least one episode of pneumonia.
The changes in indoor environmental exposure caused by
the modernization of China may in part explain the increas-
ing prevalence of the studied diseases. Certainly, further
analyses and research (composition and size effect of PM,
e.q.) are necessary to unravel the riddles behind the rapid
increases. In Phase II, case-control studies in which pollu-
tants in air, dust and urine are measured, will be done. Na-
tion-wide collaborative research among inter-disciplinary
fields and groups will be needed.
This work was supported by the National Natural Science Foundation of
China (51136002, 51076079, 51006057), Ministry of Science and Tech-
nology of China (2012BAJ02B03) and National High Technology Research
and Development Program of China (2010AA064903). The authors are on
behalf of CCHH Phase I collaborative group. Sun YueXia and Mo JinHan
were the scientific secretaries for the papers. We also thank Zhang JP,
Wang H for their contribution in this study, and Louise B. Weschler for
careful revisions of the manuscript.

Zhang Y P, et al. Chin Sci Bull January (2013) Vol.58 No.1 7
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Open Access This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction
in any medium, provided the original author(s) and source are credited.
Supporting Information
Table S1 Comparison between short questionnaires and Phase I questionnaires in Chongqing
Table S2 Summary of general characteristics of the study populations, children 1–8 years old (%)
Table S3 Summary of building characteristics in the investigated regions, children 1–8 years old (%)
Table S4 Dampness and odor indices in homes in the investigated regions, children 1–8 years old (%)
Table S5 Questionnaire used in CCHH Phase I
The supporting information is available online at csb.scichina.com and www.springerlink.com. The supporting materials
are published as submitted, without typesetting or editing. The responsibility for scientific accuracy and content remains en-
tirely with the authors.