The European Journal of Public Health Advance Access originally published online on May 9, 2006
The European Journal of Public Health 2006 16(6):676-681; doi:10.1093/eurpub/ckl061
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Respiratory symptoms and lung function in Bangkok school children
Uma Langkulsen1, Wanida Jinsart2, Kanae Karita3 and Eiji Yano3
1 International Postgraduate Program in Environmental Management NRC-EHWM Chulalongkorn University, Bangkok, Thailand
2 Department of General Science, Faculty of Science, Chulalongkorn University, Bangkok, Thailand
3 Department of Hygiene and Public Health, Teikyo University School of Medicine, Tokyo, Japan
Correspondence: Associate Prof. Dr Wanida Jinsart, Department of General Science, Faculty of Science, Chulalongkorn University, Phayathai Road, Bangkok 10330, Thailand, tel: +66 2 2185181-3, fax: +66 2 2185180, e-mail: jwanida{at}chula.ac.th
Received June 28, 2005, accepted March 28, 2006
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Abstract |
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Background: Previous epidemiological studies have shown acute effects of ambient air pollutants in children with respiratory disorders. Methods: The chronic effects of air pollution in Bangkok children were investigated. Children aged 10–15 years were examined for lung functions using spirometry tests and for respiratory symptoms by the American Thoracic Society's Division of Lung Diseases (ATS-DLD-78-C) questionnaire during May–August 2004. Effects of residential area were estimated by multiple logistic regression analysis. Of the 878 children, 722 (82%) had completed lung function test and ATS-DLD questionnaire. Results: In children, who live in roadside (R) and general (G) areas with high (H) pollution, the prevalence of respiratory symptoms increased significantly [odds ratios (95% confidence interval) in HR and HG are 2.44 (1.21–4.93) and 2.60 (1.38–4.91), respectively]. Children with normal lung function were less observed in H- and M-polluted roadside and general area [HR, OR = 1.41 (95% CI 0.89–2.22); HG, 1.08 (0.71–1.64); and MR, 0.99 (0.63–1.57)]. Residential locations and family members were associated with the prevalence of respiratory symptoms, whereas factors such as the responder of ATS-DLD, gender, age, residential years, home size, parental smoking habits, use of air conditioners, and domestic pets were not associated. Age was associated with the impaired lung function, whereas others factors were not associated. Conclusion: The prevalence of respiratory symptoms and impaired lung function were higher among children living in areas with high pollution than those in areas with low pollution.
Keywords: air pollution, Bangkok, children, lung function, respiratory symptoms
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Introduction |
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Epidemiological studies found relatively consistent associations between outdoor particulate matter concentrations and various adverse health effects, such as exacerbation of asthma, other respiratory tract diseases, and decrements in lung function.1–12
The high concentration of respirable particulate matter (PM10) in ambient air is one of the serious environmental problems in Bangkok city, particularly in the traffic-congested areas. PM10 levels were monitored systematically at 32 Pollution Control Department (PCD) monitoring stations. In many areas, annual average PM10 concentrations were found to be higher than the National Ambient Air Quality Standard. In 2004, annual average concentrations of total suspended particulate matter (TSP) and PM10 at roadside monitoring stations were 
0.18 mg/m3 and 78.50 µg/m3, exceeding the standard13 by 8.3 and 8.4% days, respectively. There is a potential increase in the concentration of pollutants each year. Furthermore, PM10 in Bangkok has been associated with serious health effects, such as increased hospital admissions and mortality.14 The associations were also reported between air pollution and respiratory health among traffic policemen15–18 and their wives.19 These studies have mainly been conducted in healthy adult groups. It is not clear to what extent such associations could be revealed in children, who might be more susceptible to air pollution than adults. A few researchers have reported that there is an increase in respiratory symptoms20 and impaired lung function among asthmatic children near Maemoh Power Plant, Thailand.21 However, chronic health effects for the children remain uncertain, particularly for Bangkok children. Therefore, with the help of a cross-sectional design, possible chronic effects of exposure to air pollution in Bangkok school children were investigated. The aim of this study was to evaluate the association between air pollution and respiratory symptoms, or lung function, by using the ATS-DLD-78-C respiratory questionnaires and spirometry tests among the school children in different air pollution levels.
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Methods |
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Study site and population
Bangkok has a population of about six million people with a very high density (4051 persons per square kilometre). To obtain a wide range of air pollution level, four different areas were selected based on the traffic volumes and population density. Based on the level of PM10 obtained from PCD monitoring stations, four areas (highly polluted roadside area: HR; highly polluted general area: HG; moderately polluted roadside area: MR; and less-polluted area as a control: C) with elementary and junior high schools were chosen. Figure 1 shows the location of the studied areas. Annual average PM10 level in 200413 at Din Daeng Housing Authority Station located in HR was 65 µg/m3, and this level too exceeds the standard 50 µg/m3. There were 12 out of 354 observations, representing 3.4% of the total observations, where concentrations exceed the standard 120 µg/m3. The concentration level at Nonsi Withaya School Station located in HG was 67.5 µg/m3. There were 20 out of 354 observations, representing 5.7% of the total observations, where concentrations exceed the standard. At Thonburi Substation Station located in MR, the level was 52.2 µg/m3. There were 4 out of 361 observations, representing 1.1% of the total observations, where concentrations exceed the standard and at Khlong Chan Housing Community Station located in C, the level was 47 µg/m3. There were 2 out of 366 observations, representing 0.6% of the total observations, where concentrations exceed the standard (Table 1).
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In 2004, school children aged 10–15 years were recruited for the study. Simple random sampling was used in the selection of one elementary school and one junior high school in each area that are close to or within 2 km of a PCD roadside and ambient air quality monitoring station. Total study subjects were 878 school children summed up to 10% of total children in each school. Systematic sampling in odd personal numbers of school students aged 10–12 and 13–15 years living in the four study areas were chosen. Exposure level of air pollution to each child was derived from the monitoring station nearest to his or her school in HR, HG, MR, and control areas. The overall participation rate was high (82%).
Respiratory questionnaires
The prevalence of chronic respiratory symptoms (non-specific respiratory disease: NSRD and persistent cough and phlegm: PCP) were assessed using Thai version of ATS-DLD-78-C.22 Criteria for NSRD are (i) chronic bronchitis: phlegm production from the chest 
two times/day for 4 days/week for 3 months/year for at least 3 years; (ii) bronchial asthma: doctor-diagnosed asthma and still have asthma; (iii) dyspnea and wheezing: wheezing or whistling in the chest apart from cold on most days or nights. Criteria for PCP are (i) persistent cough: cough apart from cold on most days more than 4 days/week for 3 months/year for at least 1 year; and (ii) persistent phlegm: congested in the chest or bring up phlegm, sputum, or mucus apart from cold on most days more than 4 days/week for 3 months/year for at least 1 year.
The questionnaire consists of general information, respiratory symptoms (cough, phlegm, wheeze, chest tightness), and family history. Either of the parents of children completed the respiratory questionnaire after the children were examined for their lung functions (HR = 152, HG = 207, MR = 150, and C = 213 cases).
Lung function test
Lung function was measured by automated spirometry (Pony Graphic 3.3, Cosmed, Italy) using Spiro Thai 2.0 Program, according to the predicted lung function parameters from reference values in the Thai population.23 Spirometric measurements include forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), FEV1/FVC%, and forced expiratory flow between 25 and 75% expired volumes (FEF25–75%).
Three experienced lung function technicians, who received certifications from the Cardiopulmonary Thailand Association under American Thoracic Society (ATS)24, performed the spirometry tests in each school after regular calibration of spirometers. Standing height and weight were measured using the standardized equipments and procedures in all schools. Lung function was measured during May–August 2004 (HR = 212, HG = 225, MR = 226, and C = 215 cases). All subjects were trained by technicians for their proper blowing as fast, hard, and long as possible, with at least three spirometry tests in the seated position. The best spirogram with the highest sum of FVC and FEV1 was chosen for further analyses. Test acceptability was determined by examining the flow and volume time curve as recommended by ATS. FEV1 and FVC [greater than] 80% predicted were used as the criteria for normal lung function.
Statistical analysis
Differences in the health-related parameters among the areas of HR, HG, MR, and control groups were compared using Yates' chi-squared test.25 Logistic regression techniques were used to assess the dependency between prevalence of respiratory symptoms, lung function, and independent variables such as responder (mother = 1, father or others = 0), gender (male = 1, female = 0), age, residential years, home size, family members, parental smoking habits (mother or father or both smoke = 1, neither smoke = 0), use of air conditioners (yes = 1, no = 0), and having domestic pets (yes = 1, no = 0). The factor of residential areas as categorical covariate and the control area were used as a reference category. Three dummy or indicator variables denoting areas were included in this model (HR = 1, HG = 2, MR = 3, and C = 4). The regression models were tested using any of the respiratory symptoms and impaired lung function as dependent variables, and the area and others as independent variables listed above. The odds ratios (ORs) and 95% confidence intervals (CIs) were treated as the outcome variables and precision weighting was applied to estimate the degree of association in this study. The data were analysed by the statistical program SPSS version 13.0 (SPSS Inc., Chicago, IL, USA, 2001).
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Results |
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Lung function was measured in 872 (99.3%) of the 878 children aged 10–15 years, as 2 (0.2%) children showed major signs of upper respiratory tract infections and 4 (0.4%) children refused to participate in the study. After evaluating the flow-volume curves applied to the criteria of ATS, data from 844 (96%) children were acceptable for further analyses. Among them 722 (82%) completed the respiratory questionnaire. Table 2 shows the demographic and risk factor characteristics of the 722 children in each study group. Sixty per cent of the ATS-DLD questionnaire was completed by mothers. There were 354 boys and 368 girls, and 37% of them have been living in their areas for more than 10 years. They lived in the same place for at least 6 months before the survey.
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Table 3 shows the prevalence of respiratory symptoms and impaired lung function of children. The prevalence of respiratory symptoms was shown to be higher for chronic bronchitis, bronchial asthma, dyspnea and wheezing, persistent cough, and persistent phlegm in the HR, HG, and MR areas than in the C area (dyspnea and wheezing in junior high school students in HR and HG areas, P < 0.01). The prevalence of chronic bronchitis, persistent cough, and persistent phlegm were higher significantly in elementary students in HG area compared with those in C area (P < 0.05). A significant higher prevalence of any one of the respiratory symptoms was observed in junior high school students in HR and HG areas (P < 0.01) and in elementary students in HG area (P < 0.05) compared with those in C area. The percentage of impaired lung function in junior high school students, who live in HR, HG, and MR areas, was significantly higher than in the C area (P < 0.01). There was no significant difference in the bronchial asthma.
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The results of the multiple logistic regression analyses were shown in Table 4. To evaluate the significant factors on any one of the respiratory symptoms or impaired lung function, independent variables such as the responder of ATS-DLD, gender, age, residential years, home size, family members, parental smoking habits, use of air conditioners, domestic pets, and residential areas were included in this model. In children who live in HR and HG areas, the prevalence of respiratory symptoms increased significantly compared with those living in the control area. Family members slightly increased the significance of the prevalence of respiratory symptoms and age slightly increased the significance of the risk of impaired lung functions. Restricted only to the children whose mother completed the ATS-DLD questionnaires (n = 436), family members significantly increased the prevalence of respiratory symptoms (OR = 1.20, 95% CI = 1.05–1.37) and age slightly increased the significance of the risk of impaired lung functions (OR = 1.19, 95% CI = 1.07–1.34). Residential areas and family members were associated with the prevalence of respiratory symptoms and age was associated with impaired lung function significantly, whereas factors such as the responder of ATS-DLD, gender, residential years, home size, parental smoking habits, use of air conditioners, and domestic pets were not associated.
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Discussion |
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Children living in highly polluted areas would possibly indicate higher prevalence of respiratory symptoms and impaired lung function than those living in moderately and less-polluted areas. In this study, we categorized the children into eight groups based on area, school type, roadside and ambient monitoring stations and have found that children living in highly polluted areas suffered more frequently with respiratory symptoms and decreased lung functions compared to those children who live in less-polluted areas. Junior high school students in HR area have the greatest impaired lung functions. Both elementary and junior high school students in HR and HG areas illustrated the higher prevalence of respiratory symptoms compared to children in other groups. It is obvious that air pollution affects more on children who have been living for a long time in highly polluted areas of Bangkok than on children who live in less-polluted areas. There were differences in associations between pollutants and respiratory symptoms for elementary students and junior high school students. There may be junior high school students living for a longer period in their polluted areas more than the elementary students. There may be children of younger ages who are sensitive to these respiratory symptoms. These groups correspond with both biological development and the type of care for those families. In addition, we confirmed the observation after controlling other risk factors. There seems to be greater effects of air pollution on the respiratory symptoms and lung function in school children compared to adults as having shown in other cities.1–12 Our studies also suggested that children who live in highly polluted areas were susceptible to adverse health effects.
Lung function tests for children were performed in the seated position and without nose clip. ATS guidelines24 suggest that subjects can be tested either seated or standing and a report from school-age children who were tested with and without nose clips found no systematic effect on FEV1 or FVC.26 After the flow-volume curve examinations, we found high proportion of valid tests. Therefore, we believed that the lung function tests were performed satisfactorily. There may be an area difference in the proportion of time for the children spending outdoors. Outdoor pollutants may affect them more if they stayed outdoors longer. According to the population density, Bangkok Metropolitan Administration has divided the city into three zones, inner, middle, and outer zone, in accordance with the population density. Khlong Chan Housing Community Station as our control site, located in the middle zone and HR and HG areas located in the inner zone. The results revealed the association between site conditions and the health effects. The prevalence of respiratory symptoms was higher among children living in HR and HG areas than those children living in other groups. We assumed that children in control area, in the middle zone, low population density, have more chance to play outdoors than those living in busy streets in inner areas. Thus without considering the difference in playing outdoors, there may be even larger difference in the effect of air pollution among the areas. In addition, there may be other potential confounders such as unaccounted differences in socio-economic variables. Lenth et al.27 showed that socio-economic status (SES) affected health conditions. However, most of the parents of the children in this study were considered to be of the middle class and the inclusion of variables such as air conditioners use, home size, family members, and respondents of the questionnaire in the multiple logistic analyses may adjust the remaining effect of SES. In addition, the prevalence of some respiratory symptoms, such as chronic bronchitis, dyspnea and wheezing, persistent cough, and phlegm, may be associated with the residential area, which may in turn be associated with low-SES. This could lead to a confounding bias if children with low-SES were probably living in near busy streets. Therefore, if poorer families are unable to afford to live in cleaner areas and as a result their children's respiratory health suffers, this would suggest that PM10 is one of the potential mechanism by which SES affects health. Family members were associated significantly with the prevalence of respiratory symptoms. People with weakened immune systems can be especially susceptible to more severe complications, such as bronchial infections. There can be any family members who suffer from allergies, asthma, or other respiratory problems. In addition, they may have immune system problems or illness and smoke inside their houses. Overall, in more than half of the households (60.4%), mothers were the questionnaire respondents. Normally, mothers were more likely to report a symptom or illness than the other questionnaire respondents. However, this study found mother or father or other were not associated significantly with reporting the prevalence of any of the respiratory symptoms. Nature of Thai people likes to take care of their children and to be very familiar. Some children may live with father only or with family senior relatives, because their parents were very busy at work. It is possible that mother or father or the other be equal in raising their children and can give reliable symptoms details.
The percentage of the willingness to participate in our study was high and the children included in the analyses should be reasonably representative of all children of a similar age in Bangkok. In line with the results from previous studies, children with asthma, wheezing, or a positive provocation challenge have a greater variability in lung function than in healthy children.2
This work was in the beginning stage of health effect study in Bangkok children. Since, the cross-sectional study was applied, the causal association may not be determined. However, from the results, we could suggest that living in highly polluted areas in Bangkok will lead to the chronic effects on respiratory systems in addition to the acute health effects as reported by previous studies.
Key points
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Acknowledgments |
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We are deeply grateful to the parents and children who participated in our study. The Royal Golden Jubilee (RGJ) PhD Program Thailand Research Fund and National Research Center-Environmental Hazardous Waste Management (NRC-EHWM), Thailand, financially supported this research.
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1 Jedrychowski W, Flak E, Mroz E. The adverse effect of low levels of ambient air pollutants on lung function growth in preadolescent children. Environ Health Perspect 1999;107:669–74.[Web of Science][Medline]
2 Boezen HM, van der Zee SC, Postma DS, et al. Effects of ambient air pollution on upper and lower respiratory symptoms and peak expiratory flow in children. Lancet 1999;353:874–8.[CrossRef][Web of Science][Medline]
3 Braun-Fahrlander C, Vuille JC, Sennhauser FH, et al. Respiratory health and long-term exposure to air pollutants in Swiss school children. Am J Respir Crit Care Med 1997;155:1042–9.[Abstract]
4 Collier AM, Pimmel RL, Hasselblad V, et al. Spirometric changes in normal children with upper respiratory infections. Am Rev Respir Dis 1978;117:47–53.[Web of Science][Medline]
5 Dockery DW, Speizer FE, Stram DO, et al. Effects of inhalable particles on respiratory health of children. Am Rev Respir Dis 1989;139:587–94.[Web of Science][Medline]
6 Gauderman WJ, McConnell R, Gilliland F, et al. Association between air pollution and lung function growth in Southern California children. Am J Respir Crit Care Med 2000;162:1383–90.
7 Hoek G, Dockery DW, Pope A, et al. Association between PM10 and decrements peak expiratory flow rates in children: reanalysis of data from five panel studies. Eur Respir J 1998;11:1307–11.[Abstract]
8 Horak F, Jr, Studnicka M, Gartner C, et al. Particulate matter and lung function growth in children: a 3-yr follow-up study in Austrian schoolchildren. Eur Respir J 2002;19:838–45.
9 Schwartz J. Lung function and chronic exposure to air pollution: a cross-sectional analysis of NHANES II. Environ Res 1989;50:309–21.[Medline]
10 Timonen KL, Pekkanen J, Korppi M, et al. Prevalence and characteristics of children with chronic respiratory symptoms in eastern Finland. Eur Respir J 1995;8:1155–60.[Abstract]
11 Ware J, Dockery D, Spiro AI, et al. Passive smoking, gas cooking, and respiratory health of children living in six cities. Am Rev Respir Dis 1984;129:366–74.[Web of Science][Medline]
12 Gauderman WJ, Avol E, Gilliland F, et al. The effect of air pollution on lung development from 10 to 18 years of age. N Engl J Med 2004;351:1057–67.
13 Pollution Control Department, Ministry of Natural Resources and Environment. State of Thailand's Pollution in Year 2004. Bangkok, Thailand: Pollution Control Department, 2005.
14 Ostro BD, Chestnut LG, Vichit-Vadakan N, et al. The impact of particulate matter on daily mortality in Bangkok, Thailand. J Air Waste Manage Assoc 1999;49:100–7.[Medline]
15 Wongsurakiat P, Maranetra N, Nana A, et al. Respiratory symptoms and pulmonary function of traffic policemen in Thonburi. J Med Assoc Thai 1999;82:435–43.[Medline]
16 Karita K, Yano E, Jinsart W, et al. Respiratory symptoms and pulmonary function among traffic policemen in Bangkok. Arch Environ Health 2001;56:467–70.[Web of Science][Medline]
17 Jinsart W, Tamura K, Loetkamonwit S, et al. Roadside particulate air pollution in Bangkok. J Air Waste Manage Assoc 2002;52:1102–10.
18 Tamura K, Jinsart W, Yano E, et al. Particulate air pollution and chronic respiratory symptoms among traffic policemen in Bangkok. Arch Environ Health 2003;58:201–7.[Web of Science][Medline]
19 Karita K, Yano E, Tamura K, Jinsart W. Effects of working and residential location areas on air pollution related respiratory symptoms in policemen and their wives in Bangkok, Thailand. Eur J Public Health 2004;14:24–6.
20 Aekplakorn W, Loomis D, Vichit-Vadakan N, et al. Acute effects of SO2 and particles from a power plant on respiratory symptoms of children, Thailand. Southeast Asian J Trop Med Public Health 2003;34:906–14.[Medline]
21 Aekplakorn W, Loomis D, Vichit-Vadakan N, et al. Acute effect of sulphur dioxide from a power plant on pulmonary function of children, Thailand. Int J Epidemiol 2003;32:854–61.
22 Ferris BG. Epidemiologic Standardization Project. Am Rev Respir Dis 1978;118:1–88.[Web of Science][Medline]
23 Dejsomritrutai W, Nana A, Maranetra KN, et al. Reference spirometric values for healthy lifetime nonsmokers in Thailand. J Med Assoc Thai 2000;83:457–66.[Medline]
24 American Thoracic Society. Standardization of Spirometry 1994 update. Am J Respir Crit Care Med 1995;152:1107–36.[Web of Science][Medline]
25 Wayne WD. Biostatistics: A foundation for analysis in the health sciences. 2nd edn. New York: John Wiley & Sons Inc., 1978
26 Chavasse R, Johnson P, Francis J, et al. To clip or not to clip? Noseclips for spirometry. Eur Respir J 2003;21:876–8.
27 van Lenth FJ, Schrijvers CTM, Droomers M, et al. Investigating explannations of socio-economic inequalities in health. The Dutch GLOBE study. Eur J Public Health 2004;14:63–70.
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