Medical Reports & Case Studies

A Longitudinal Study on Respiratory Morbidity due to Air Pollution in an Industrial Town Mandi Gobindgarh, Punjab, India

Manoj Kumar^* and Savita Prashar ^*Correspondence: Dr. Manoj Kumar, Department of Public Health, University of Punjab, Chandigarh 160014, India, Tel: 9417160566, Email:

Author info »

Introduction

In last 50 years of industrial revolution and regulatory reforms, India is trying to improve its air quality [1]. The Ministry of Environment, Forest and climate change, Government of India has identified Industrial Town Mandi Gobindgarh as one of the critically polluted area in the country [2]. In order to evaluate the risk aspects due to air pollution at the general population levels, several factors have to be considered, i.e., exposure dose, biological effect and proportion of the Industrial Town population. The results of these studies are difficult to interpret because of a variety of limitations mostly regarding exposure assessment and handling of cofactors [3]. Chronic Obstructive Pulmonary Disease (COPD) is one of the leading causes of morbidity and mortality both in the industrialized and the developing countries. The burden of this respiratory disease worldwide is expected to increase and have an impact on the individual and the society [4]. The disease contribute an immense in this country as well [5,6]. An attempt has been made in the past to estimate the gross burden of Chronic Obstructive Pulmonary Disease (COPD) in India [5]. The median values of prevalence rates from published studies were 5.0 percent in male and 2.7 percent in female population [5]. These results also substantiated by a multi-centric epidemiological study from India [7]. But the role of air pollutants has not been clearely studied from India. This is a follow up study aimed to evaluate the effects of air pollutants on respiratory morbidity among adults in representative samples of two populations one each in industrial town of Punjab.

Materials and Methods

Study area

Industrial Town Mandi Gobindgarh is located at latitude of 30.66N and a longitude of 76.31E, having an area of 32 Km² and population of 55,400 as per the census report for the year 2001.

Study design

Longitudinal study was conducted in the “Industrial Town” of Punjab with a view to collect the data pertaining to socio-demographic factors, occupational history, life style (including smoking), respiratory symptoms and lung functions. Ambient air quality data were assessed for a period of two year. The sample size was approximately 1000 for the Industrial Town populations for the year 2001 and 2021. According to cluster sampling scheme, two colonies were selected from industrial town. Interview was carried out based on a structured questionnaire. The questionnaire on respiratory symptoms was tailored on the questions listed by the British Medical Research Council, UK, American Thoracic Society, and International Study of Asthma and Allergies in Childhood (ISAAC) schedules. The questionnaire pertained to the questions on socio-economic characteristics, household environment, respiratory symptoms, smoking history, residence and occupational history. To assess the socio-economic status, modified Kuppuswami scale was used. Data collection was collected for a follow up in the year 2001 and 2021 [9]. It consisted of interview and physical examination of the individual and the air sampling in industrial towns.

Interview and physical examination

The individuals were interviewed by using an interview schedule. After completion of the interview, the physical examination was carried out and measurements were made for, height and weight.

Air quality monitoring

Air quality monitoring was done by the High Volume air Sampler (HVS) (Envirotech APM 460), every week, for particulate matter less than ten micron size (PM₁₀), TSP, NO_x, SO_x and O₃. Weekly sampling by the Organic Vapour Sampler (OVS) (Envirotech APM 850) was done for CO and data was collected from other sources like State Pollution Control Board and compared between year 2001 and 2021.

Statistical analysis

Suitable statistical test like Chi-square test was used to test significant difference, in the categorical and t-test for quantitave variables. T-test was used to compare means values of years of residence, smoking duration and smoking index. Odds ratio and 95% confidential intervals for residence in industrial town were estimated using binary logistic regression analysis in SPSS programme.

Results

Level of air pollution

Level of PM₁₀ was 110.2 μg/m³ in year 2001 and 122.8 μg/m³ in year 2021 in study town. Levels of all the pollutants were higher in year 2021 as compared to 2001 after the follow up of 20 years (Table 1). Daily and yearly variations of all the parameters were under permissible limit except PM₁₀ and Total Suspended Particulate matter (TSP) between 2001 and 2021. Levels of all the pollutants were higher in Industrial Town during this period.

Table 1. Air pollutants with permissible limits in 2001 and 2021.

Study population characteristics

For the household survey, 1003 subjects were selected from the Industrial Town in 2001 and 1001 subjects in year 2021. There was equal distribution of men and women in the two sample groups, only than having age more than 20 years were sampled. The level of higher socio-economic status, current smoking, passive smoking, and biomass fuel use, household environment such as inadequate light, inadequate ventilation and dampness, moderate to severe dust exposure, immigrants and factory workers were higher in the year 2021. Therefore, prevalence of respiratory morbidities was compared according to socio-economic status, smoking, biomass fuel use, dust exposure, immigrants and factory workers in both the towns.

Increase in chronic respiratory morbidities

It was found that prevalence of cough and phlegm in Industrial Town was 30.9% and 27.2% respectively in total population, which were significantly in 2021 (Table 2). It was found that prevalence of breathlessness and wheezing in Industrial Town were 33.3% and 16.7% in total population, which were significantly higher in 2021 (Table 3). Prevalence of COPD and asthma was significantly higher in total population of Industrial Town (22.3% and 8.8% respectively) in 2021 as compared to 2001 (Table 4). The population characteristics in Industrial Town were not similar in 2001 and 2021 with respect to socio-economic status, smoking, use of biomass fuel, ethnically and length of residence in the town. Some of these characteristics particularly smoking, use of biomass fuel and occupation have been shown to be associated with chronic respiratory morbidities. Therefore, prevalence of respiratory morbidity was compared in stratified analysis in smokers and nonsmokers users of biomass fuel and non-users of biomass fuel and among occupational socio-economic, migrant and resident groups. The prevalence of respiratory morbidities was significantly higher in Industrial Town even in nonsmokers, non-biomass fuel users, among those having higher socio-economic status, in 2021 as compared to 2001. Confounding in these variables was evaluated in multivariate analysis. After controlling the effect of age, sex, socioeconomic status, smoking, biomass fuel use, inadequate lighting, inadequate ventilation, dampness, residence duration, dust exposure, factory workers and migrant population by using binary logistic regression models on individual symptoms Adjusted Odds Ratio for, Chronic Obstructive Pulmonary Disease (COPD) in year 2021 was (OR=4.01, 95% CI 1.72-5.92 P=0.01) as compared to year 2001 i.e. (OR=2.23, 95% CI 1.10-4.53 P=0.03) were found significantly higher after a follow up of 20 years in the residents of Industrial Town. Symptoms for cough, phlegm, dyspnea, wheeze, asthma and COPD were significant associated with poor ambient air quality exposure for long term. Whereas tuberculosis were not significant in the area of poor ambient air quality in 2021 as compared to 2001. Smoking, biomass fuel, duration of residence and migration were independently associated with respiratory morbidity. The ambient air quality was poorer in due to high PM₁₀ and TSP and could be responsible for high prevalence of cough, phlegm, dyspnea, wheeze and COPD was also observed in Industrial Town between 2001 and 2021. Similarly association of poor air quality with chronic respiratory morbidity has observed in other studies.

Table 2. Prevalence of cough and phlegm in 2001 and 2021.

Table 3. Prevalence of Breathlessness and Wheezing in 2001 and 2021.

Table 4. Incidence of respiratory diseases in 2001 and 2021.

Discussion

The acute effects of air pollution have stimulated the interest of epidemiologists and clinicians, and several studies were published focusing on the associations between adverse respiratory symptoms and concentrations of air pollutants on long term exposure. Time series studies have shown that air pollution is associated with increased hospital admissions and mortality due to cardiorespiratory diseases as pre-existing conditions aggravate with rise in air pollution. However, long term effects of ambient air pollution in causing chronic respiratory problems such as COPD and asthma, have been less clear. Air quality was monitored in the study area for PM₁₀, TSP, NO_x, SO_x, CO and O₃ by using standard methods prescribed by Bureau of Indian Standards (BIS) [10-14]. Concentrations of air pollutants are compared with the standards of ambient air quality that have been set for Indian climate by CPCB, World Health Organization (WHO) and United State of Environment Protection Agency (USEPA). Level of PM₁₀, TSP, NO_x, SO_x, CO and O₃ were significantly higher in 2021 as compared to 2001. Only the level of SPM was more than the permissible limits of CPCB and USEPA in Industrial Town. Only the level of Total Suspended Particulate matter (TSP) was observed more than permissible limit in Industrial Town. Level of monthly means of Total Suspended Particulate matter (TSP) in year 2001 was 890.3 μg/m³ while in 2021 it is 946.4 μg/m³. Levels of all the pollutants were higher in Industrial Town than in Non- Industrial Town (Table 1). Level of TSP is increased alarming stage between 2001 and 2021. PM₁₀ is considered to be more sensitive parameter than TSP. Concentration of PM₁₀ in Industrial Town was mostly more than the permissible limit of CPCB. Level of monthly mean of PM₁₀ was 110.2 g/m³ in year 2001 and 122.8 μg/m³ in year 2021. The level of air pollutants in study area during year 2001 was less as compared to year 2021. Reason for increase in the level of TSP in 2021 could be due to the increase in the number of vehicles, construction work, population and industries. The prevalence of cough, phlegm, breathlessness and wheezing in year 2021 were 30.9%, 27.2%, 33.3% and 16.7% in total population. Kamet, et al. has reported the prevalence of chronic cough in the range of 1.7% to 5.1% and dyspnea range from 3.2% to 7.2% in Mumbai. Chronic cough was 12% and 11.2% in Parel and Lava whereas dyspnoea was 53% and 13% respectively. Jindal, et al. have reported asthma prevalence of 3.9% in urban males, 3.9% in rural males, and 1.3% in both urban and rural females from north India [5]. Gupta, et al. have reported asthma in 3.3% children who were not Industrial Town to environmental tobacco smoke [13]. According to ISSAC study (1998) asthma prevalence was 2.8% among children in Chandigarh. In this study COPD prevalence was 22.3% among total population in Industrial Town in year 2021. Jindal, et al. reviewed 14 studies, to estimate the gross burden of Chronic Obstructive Pulmonary Disease (COPD) [5]. The median values of different prevalence rates were 5% in male and 2.7% in female population. In three urban areas of Mumbai prevalence of COPDranged from 2.3% to 4.5% Bakke, et al. has reported chronic bronchitis in 5.4%. Prevalence of self-reported tuberculosis among total population was 2.4% in year 2021 [15]. The prevalence of tuberculosis was reported as 0.4% in India. In a study spirometer standards developed by Jindal and Wahi, for north India population were used [16-20]. Chhabra, et al. also found that subjects those who were Industrial Town to poor ambient air quality due to high level of SPM had poor lung function tests in Delhi [8]. Similarly studies by Detels R. et. al [11] and Pope, et al. [21] have also reported association of poor air quality and higher respiratory morbidity in USA. Kamat, et al. [9] showed a higher morbidity with raised levels of air pollution in 3 urban and a rural community of Mumbai. In the respective 4 areas standardized prevalence were: for dyspnea 7.3%, 6%, 3.2% and 5.5%; for chronic cough 5.1%, 2.7%, 1.7% and 3.3%; for COPD4.5%, 4.5%, 2.3% and 5.0%. In present study association between poor ambient air quality was found with adjusted Odds Ratio for, Chronic Obstructive Pulmonary Disease (COPD) in year 2021 was (OR=4.01, 95% CI 1.72-5.92 P=0.01) as compared to year 2001 i.e. (OR=2.23, 95% CI 1.10-4.53 P=0.03). This is supported by study of Wong, et al. which shows a significant effects of air pollution on morning cough (OR=1.65, 95%CI: 1.03–2.64), phlegm in morning (OR=1.40, 95%CI: 1.03–1.92), phlegm day or night (OR=1.63, 95%CI: 1.10–2.42) and phlegm for three months (OR=1.70, 95%CI: 1.13 – 2.56) in nonsmoking women in high polluted area. The odds ratio (OR) for the distinct effect was 1.55, which is consistent with Dockery’s statements that the health effects of air pollution observed in the cites of the United States would usually be weak, with a relative risk of less than 2 and often less than 1.5 for typical exposure [7]. In this study subjects Industrial Town to poor ambient air quality significantly associated with Chronic Obstructive Pulmonary Disease (COPD) in year 2021 was (OR=4.01, 95% CI 1.72-5.92 p=0.01. These results are in accordance to study done by Karita, et al. who reported an increase in prevalence of obstructive changes in the peripheral airways among traffic police in Bangkok [21-27]. Ostro, et al. found that air borne H+ was significantly associated with several indicators of asthma status, including moderate or severe cough and shortness of breath [22-30]. Zemp, et al. in a crosssectional study in random population samples of adults at eight study sites in Switzerland reported independent, positive association between annual mean concentrations of NO₂, total suspended particulates, and particulates of less than 10 μm in aerodynamic diameter (PM₁₀) with prevalence of chronic phlegm production, chronic cough or phlegm production, breathlessness at rest during the day, breathlessness during the day or at night, and dyspnea on exertion [31-37]. They found no associations with wheezing without cold, current asthma, chest tightness, or chronic cough. Among never-smokers, the odds ratio (95% CI) for a 10 μm/m³ increase in the annual mean concentrations of PM₁₀ was 1.35 (1.11 to 1.65) for chronic phlegm production, 1.27 (1.08 to 1.50) for chronic cough or phlegm production, 1.48 (1.23 to 1.78) for breathless during the day, 1.33 (1.14 to 1.55) for breathlessness during the day or night, and 1.32 (1.18 to 1.46) for dyspnea on exertion. Similar associations were also found for former and current smokers, except for chronic phlegm production. The observed associations remained stable when further control was applied for environmental tobacco smoke exposure, past and current occupational exposures, atopy, and early childhood respiratory infections when restricting the analysis to long-term residents and to non-alpine areas, and when excluding subjects with physiciandiagnosed asthma [28]. Peter, et al. conducted a ten year prospective cohort study of Southern California children, with a study design focused on four pollutants; ozone, particulate matter, acids, and nitrogen dioxide (NO₂). Wheeze prevalence was positively associated with levels of both acid (OR=1.45; 95%Cl, 1.14.83), and NO₂ (OR=1.54; 95%Cl, 1.08-2.19) in boys. In the present study dyspnea (OR=1.41, 95%CI 1.09-1.78, P=0.01) and asthma (OR=2.27, 95%CI 1.12-4.59, P=0.03) was significantly associated with poor ambient air quality [34]. Chhabra, et al. studied the magnitude of the problem of childhood asthma in India and the factors influencing its occurrence. Multiple logistic regression analysis showed that male sex, a positive family history of atopic disorders, and the presence of smokers in the family were significant factors influencing the development of asthma whereas socio-economic class, air pollution (total suspended particulates), and type of domestic kitchen fuel were not associated with asthma [8]. Chhabra, et al. compared nonsmoking residents of lower and higher pollution zones in Delhi stratified according to socioeconomic levels and sex. Chronic cough, chronic phlegm, and dyspnea (but not wheezing) was significantly more common in the higher-pollution zone in only some of the strata. Lung functions of asymptomatic nonsmokers were consistently and significantly better among both male and female residents of the lower-pollution zone [9]. Several times series studies have shown correlation of air pollution with hospital admission and cardiorespiratory mortality. A study by Pande, et al. on outdoor air pollution and emergency room visits at All India Institute of Medical Sciences (AIIMS) in Delhi has shown that emergency room visits for asthma, Chronic Obstructive Airway Disease (COAD) and acute coronary events increased by 21.30%, 24.90% and 24.30% respectively on account of higher than acceptable levels of pollutants [31-33]. The study of Sunyer, et al. showed that Sulphur dioxide and black smoke concentrations in the urban air of Barcelona were associated with the number of COPD emergency room admissions in both winter and summer [32]. Burnett, et al. studied the association of daily cardiac and respiratory admissions of 168 cases to acute care hospital in Ontario, Canada, with daily levels of particulate sulphates examined over the six year period 1983-1988 [6]. A 13 μg/m³ increase in sulphates recorded on the day prior to admission (the 95th percentile) was associated with a 3.7% (p<0.0001) increase in respiratory admissions and a 2.8% (p<0.0001) increase in cardiac admission. After adjusting for ambient temperature and ozone, similar increased respiratory admissions were observed in the period from April to September (3.2%) and in the period from October to March (2.8%). Results of study conducted by Chew, et al. shows that ambient air pollutant levels, in particular, those of SO₂, TSP and NO₂ were consistently associated with emergency room visits for asthma in children [7]. Damia, et al. showed that air pollutants (black smog and SO₂) correlate significantly with emergency room admissions for asthma (SO₂ [r=0.32], black smoke [r=0.35]); however, multiple regression analysis showed that black smoke was the only significantly predicator of weekly visits [10]. A cross-sectional study was carried out by Kumar, et al. to estimate the prevalence of chronic respiratory symptoms (cough, phlegm, breathlessness or wheezing) i.e. 27.9 and 20.3% and obstructive ventilatory defect i.e. 24.9 and 11.8%, in the study and Non-Industrial Town towns, respectively [28]. Logistic regression analysis showed that residence in the study town was independently associated with chronic respiratory symptoms (odds ratio [OR]=1.5; 95% confidence interval [CI]=1.2,1.8; p<0.001) and Spiro metric ventilator defects (OR=2.4; 95% CI=2.0,2.9; p<0.001) after controlling for other demographic effects [24]. This study shows that poor ambient air quality at Industrial Town was associated with high incidence of cough, phlegm, dyspnea, wheeze, chronic bronchitis and asthma but not with tuberculosis. This study provides further evidence that long-term exposure to air pollution of rather high levels of TSP is associated with higher prevalence of respiratory symptoms in adults (Tables 5 and 6) [33-38].

Table 5. Distribution of population characteristics in 2001 and 2021.

Table 6. Association of residence in poor air quality town with chronic respiratory morbidities.

Conclusion

Finally, the association between chronic respiratory morbidities with air pollution found in this longitudinal study seems to be causal in nature. Of the pollutants studied, level of Total Suspended Particulate matter (TSP) was higher between 2001 and 2021 in Industrial Town and it is an important contributor in causation of respiratory morbidity and abnormal lung functions. Level of PM₁₀, NO_x, SO_x, O₃ and CO were also more in 2021 as compared to 2001 but were below the permissible limit. Air pollutants cause damage to respiratory endothelium Pande found that people living in areas with high air pollution have increased levels of soluble intercellular adhesion molecule-1, a marker for endothelial activation. Chronic respiratory morbidities such as COPD occur after a prolonged exposure. Most study subjects are permanent residents of the town or are long time migrants to Industrial Town. They are Industrial Town to air pollution since industrialization started in this town about 60-70 years ago. The air pollution levels are alarmingly high in Indian metropolitan towns. The World Health Organization (1998) estimated 3 million premature deaths per year, mainly in acute and chronic respiratory infections, attributed to exposure to air pollution on a worldwide basis.

Acknowledgments

We thank the participants of this study.

References

1. Aggarwal, AN., et al. “Development of simple computer program for spirometry interpretation”. J Assoc Physicians India 50(2002):567-570.
2. American Thoracic Society. “Lung function testing: selection of Non-Industrial Town values and interpretative strategies”. Am Rev Respir Dis 144.5 (1991):1202-1216.
3. Asher, MI., et al. “Worldwide variation in the prevalence of asthma symptoms, International study of asthma and allergies in childhood (ISAAC)”.  Eur Respir J 12(1998):315-335.
4. Viegi, G & Di Pede, C. “Chronic obstructive lung diseases and occupational exposure”. Curr Opin Allergy Clin Immunol 2(2002):115-121.
5. Jindal, SK & Wahi, PL. “Pulmonary function laboratory in the tropics: Needs, problems and solutions”. Lung disease in the tropics (1990):523-542.
6. Jindal, SK. “Emergence of chronic obstructive pulmonary disease as an epidemic in India”. Indian J Med Res 124(2006):619-630.
7. WHO. “Air quality guidelines for Europe”. WHO regional publication series. Geneva. (1987):23.
8. Chhabra, SK., et al. “Risk factors for development of bronchial asthma in children in Delhi”.  Ann. Allergy Asthma Immunol 83(1999):385-90.
9. Kamat, SR & Doshi, VB.  “Sequential health effects study in relation to air pollution in Bombay”. Eur J Epidemiol 3(1987):265-277.
10. Damia, ADD, et al. “Effects of air pollution and weather conditions on asthma exacerbation”. Respiration 66(1999):52-58.
11. Detels, R., et al. “The UCLA population studies of chronic obstructive respiratory disease”. Am J Respir 124(1981):673-680.
12. Fletcher, C., et al. “An eight-year study of early chronic obstructive lung disease in working man in Londan”. Nat His COPD Emphysema (1965):11-189.
13. Gupta, D. et al. “Prevalence of bronchial asthma and association with environmental tobacco smoke exposure in adolescent school children in Chandigarh, North India”. J Asthma 38 (2001):501-507.
14. Health Effect Institute. “Air pollution, the automobile and public”. National Academic Press. Washington DC. (1988):19.
15. Bakke, P., et al. “Occupational dust or gas exposure and prevalence of respiratory symptoms and asthma in a general population”. Eur Respir J 4(1991):273-276.
16. Indian standard methods for measurement of air pollution (sulphur dioxide). Bureau of Indian Standard 5182(2001):2. 
17. Indian standard methods for measurement of air pollution (Suspended Particulate Matter). Bureau of Indian Standard 5182(1999):4.
18. Indian standard methods for measurement of air pollution (Nitrogen oxides). Bureau of Indian Standard 5182(1998):6.
19. Indian standard methods for measurement of air pollution. (Carbon monoxide). Bureau of Indian Standard 5182(1999):10.
20. Indian standard methods for measurement of air pollution (Ozone). Bureau of Indian Standard 5182(1986):9.
21. Pope, CA., et al. “Respiratory health and PM10 pollution. A daily time series analysis”.  Am Rev Respir Dis 144(1991):668-674.
22. Bakke, PS., et al. “Prevalence of obstructive lung disease in a general population, relation to occupational title and exposure to some air borne agents”. Thorax 46(1991):863-870.
23. Burnett, RT., et al. “Association between ambient particulate sulphate and admission to Ontario Hospitals for cardiac and respiratory diseases”. Am J Epidemiol 145(1995):15-22.
24. Chew, FT., et al. “Association of ambient air pollution levels with acute asthma exacerbation among children in Singapore”. 54(1999):320-329.
25. Chhabra, SK, et al. “Ambient air pollution and chronic respiratory morbidity in Delhi”. Arch Environ Health 56(2001):58-64.
26. Jindal, SK., et al. “A review of population studies from India to estimate national burden of chronic obstructive pulmonary disease and its association with smoking”. Indian Journal of Chest Disease and Allied Sciences 43(2001):139-147.
27. Karita, K, et al. “Respiratory symptoms and pulmonary function among traffic police in Bangkok, Thailand”. Arch Environ Health 56(2001):467-470.
28. Kumar, R., et al. “Association of Outdoor Air Pollution with Chronic Respiratory Morbidity in an Industrial Town in Northern India”. Arch Environ Health 59(2004):471-477.
29. Kuppuswami, B. “Manual of socio-economic status scale (Urban)”. Netaji Subhash Marg. Delhi. (1981).
30. Ostro, BD., et al. “Asthmatic responses to airborne acid aerosols”. Am J Public Health 81(1991):694-702. 
31. Standard Occupational Classification (SOC). Structure and description of unit groups. Office for national statistics (ONS) London. (2000).
32. Punjab State Council for Science and Technology. Status Report. Punjab Environment. (1995):28-42.
33. Pande, JN, et al. “Outdoor air pollution and emergency room visits at a hospital in Delhi”. Indian Journal of Chest Disease and Allied Sciences 44(2002): 9-11.
34. Peter, JM., et al. “A study of twelve southern Califonia communities with differing levels and types of air pollution”.  Am J Respir Crit Care Med 159(1999):760-767.
35. Sunyer, J., et al. “Air pollution and emergency room admissions for chronic obstructive pulmonary disease: A 5-year study”. Am J Epidemiol 137(1993) :701-705.
36. Wong, CM., et al. “Effects of ambient air pollution and environmental tobacco smoke on respiratory health of non-smoking women in Hong Kong”. Int J Epidemiol 28(1999):859-864.
37. Zemp, E., et al. “Long term ambient air pollution and respiratory symptoms in adults”. Am J Respir Crit Care Med 159(1999):1257-1266.
38.  Jindal, SK., et al. “Asthma epidemiological study group. A multicentric study of chronic obstructive pulmonary disease and its relationship with tobacco smoking and environmental tobacco smoke exposure”. Indian J Chest Dis Allied Sci 48(2006): 48:23-27.