|Year : 2021 | Volume
| Issue : 1 | Page : 31-38
A Cross-Sectional Study on Lung Function Status of Adults in Delhi
Suneela Garg1, Bratati Banerjee1, Gajendra Singh Meena1, Nandini Sharma2, Mongjam Meghachandra Singh1
1 Department of Community Medicine, Maulana Azad Medical College, New Delhi, India
2 Maulana Azad Medical College, New Delhi, India
|Date of Submission||02-Jan-2021|
|Date of Acceptance||02-Apr-2021|
|Date of Web Publication||28-Apr-2021|
Dr. Bratati Banerjee
DNB, Professor, Department of Community Medicine, Maulana Azad Medical College, Room no. 328, Department of Community Medicine, Maulana Azad Medical College, 2, Bahadur Shah Zafar Marg, New Delhi 110002
Source of Support: None, Conflict of Interest: None
Introduction: Air pollution is a major determinant of several lung diseases. With air pollution being a cause of concern in Delhi, present study aimed to assess proportion of individuals with impairment of lung function and factors associated with it. Methodology: A community-based cross-sectional study was conducted among adult population of Delhi. Data were collected by interview of subjects, with spirometry done on all subjects using portable spirometer. Statistical Analysis: Categorical variables were presented as percentages and compared using chi‐square test. Logistic regression analysis was done for independent predictors of lung function impairment. Significance was considered at P ≤ 0.05. Results: Total 3019 individuals were screened and 34.35% had lung function impairment, majority having restrictive disorder. Univariate analysis showed impairment was slightly higher in women, though not significant. Significantly more proportion of subjects with impairment were in higher age group, with lower levels of education, in working population and in those living in Delhi for longer duration. Students had lower risk of impairment when compared to those doing office job. Most of the findings were substantiated by multivariate analysis. Conclusion: Though spirometry is not an ideal screening test, this study does reflect that more than one-third of study subjects had impaired lung function, with those in higher age group having higher odds for lung function impairment, probably indicating the cumulative effect of air pollution. Measures for curbing air pollution are hence need of the hour and other broader determinants of health should be addressed through evidence-informed public policies and actions across all sectors.
Keywords: Air pollution, FEV1, FVC, lung function impairment, obstructive, restrictive, spirometry
|How to cite this article:|
Garg S, Banerjee B, Meena GS, Sharma N, Singh MM. A Cross-Sectional Study on Lung Function Status of Adults in Delhi. MAMC J Med Sci 2021;7:31-8
|How to cite this URL:|
Garg S, Banerjee B, Meena GS, Sharma N, Singh MM. A Cross-Sectional Study on Lung Function Status of Adults in Delhi. MAMC J Med Sci [serial online] 2021 [cited 2021 Jun 13];7:31-8. Available from: https://www.mamcjms.in/text.asp?2021/7/1/31/314870
| Introduction|| |
Air pollution in Delhi is currently a cause of serious concern. The World Health Organization’s Ambient Air Pollution Database for 2016 showed that the levels of particulate matter of size 10 micron (PM10) and PM2.5 in Delhi were way above the normal levels. The annual PM10 level was found to be 229 μg/m3 and that of PM2.5 was found to be 112 μg/m3.
Air pollution is a major cause of several lung diseases in children and adults alike. Air pollution can lead to respiratory tract infections, chronic obstructive pulmonary disease (COPD), cardiac problems, lung cancer, and a host of other diseases.,,, Several studies have shown that air pollution leads to reduction in forced vital capacity (FVC), forced expiratory volume at 1 second (FEV1), and other parameters of lung function test.,,,,
However, very few studies have been done to see the effect of exposure to air pollution on lung function of asymptomatic adults. Present study was conducted among the adult population residing in Delhi, to study the proportion of individuals with impairment of lung function test and to assess the factors associated with it.
| Materials and Methods|| |
It was a community-based cross-sectional study, conducted by the Department of Community Medicine of a Medical College in Delhi, with support from the Directorate of Health Services of GNCT of Delhi. Ethical clearance was obtained from Institutional Ethics Committee. The study was conducted at 10 sites spread over north, south, east, west, and central Delhi. The study population comprised of healthy adults aged between 18 and 50 years, residing in Delhi for ≥5 years, who volunteered for the screening test. Pregnant women and subjects who were known cases of tuberculosis were excluded from the research.
Based on a previous study conducted by Central Pollution Control Board (CPCB), showing lung function impairment among adults to be 40.3% and taking a relative precision of 5%, the required sample size was calculated by Open Epi software as 2306 (developed by AG Dean, KM Sullivan, MM Soe, version 3.03, released 2014, available at www.OpenEpi.com).
Ten data collection teams were formed one per site, each team comprising of one postgraduate student doctor, one intern, and a spirometry technician. Data were collected by interview of subjects using a pretested semistructured schedule that included sociodemographic details of the study subjects, risk factors for lung function impairment like tobacco use, exposure to secondhand smoke at home and workplace, duration of outdoor exposure per day, fuel used for cooking, and duration of stay in Delhi. Spirometry test was conducted on all subjects using portable spirometer. Results of spirometry tests were interpreted as follows: [Table 1]
Operational definitions of the parameters under consideration were as follows:
- Lung function impairment: spirometry test which showed restrictive disorder, mixed disorder, or obstructive disorder as per above criteria.
- Normal lung function: normal spirometry test as per above criteria.
- Outcome variables: presence or absence of lung function impairment.
- Sociodemographic variables: age, gender, education status, socioeconomic status, and occupation.
- Exposure variables: tobacco use, exposure to secondhand smoke at home, exposure to secondhand smoke at workplace, cooking fuel used at home, duration of outdoor exposure per day, exposure to dust, and duration of stay in Delhi.
Data were analyzed using IBM SPSS Statistics version 16.0, released 2007, IBM Corp, Armonk, NY. The categorical variables were presented as percentages. Chi‐square test was used to compare two categorical variables. Logistic regression analysis was done to find the independent predictors of lung function impairment. All tests were considered significant at P‐value ≤0.05.
| Results|| |
As it was a screening activity done in the community, it was difficult to deny screening for individuals who had volunteered to undergo the test. However, for the purpose of further analysis, only those individuals who met the inclusion and exclusion criteria were included. Being a screening program done at crowded places on volunteers, it was hard to ensure a 100% completeness of data collection schedules. For the above two reasons the total number of subjects assessed for different parameters have differed.
A total of 3019 individuals were screened and 1037 of them had impaired lung function, which gives a percentage positivity of 34.35%. Complete data were available for 2310 individuals, with 63.9% having normal lung function, 28.1% restrictive pattern of lung function impairment, 4.5% obstructive pattern, and 3.5% having mixed pattern [Figure 1].
The sitewise percentage positivity is given in [Table 2]. Total subjects screened at each center varied from 52 in Ranjeet Dispensary to 659 in the Delhi Secretariat. Percentage positivity according to center varied from 8.49% in Madan Mohan Malviya Hospital to 67.31% in Ranjeet Dispensary.
|Table 2 Sitewise distribution of lung function impairment among the screened population|
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Nearly 32.5% of the individuals screened were from the age group of 41 to 50 years and another 29.2% were from the age group of 21 to 30 years. Most of the subjects (79.5%) were men. Nearly one-third of the subjects (33.0%) were graduates and another 20% were educated up to senior secondary. Almost 27% of the subjects were doing an office job and 11.3% were students. Nearly half of the subjects (48.4%) belonged to upper socioeconomic status. More than half of the subjects (57.6%) were living in Delhi for >20 years [Table 3].
Nearly three-fourth (73.3%) of the subjects were nonsmokers. Only 15.3% were exposed to secondhand smoke at home and 27.3% were exposed to secondhand smoke at the workplace. More than half (56.5%) were exposed to outdoors every day for >6 hours and 42.9% were exposed to dust [Table 4].
|Table 4 Risk factor distribution (for lung function impairment) among the study population|
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[Table 5] shows the proportion of individuals with lung function impairment increased with an increase in age group with the highest proportion being among those in the age group of 41 to 50 years (41.9%). This association was statistically significant (P < 0.001). The proportion of women with lung impairment (36.5%) was found to be slightly higher than men (33.8); however, this was not significant. Those who have not had formal education (44.6%) and those who were educated only up to primary level (40.3%) had a significantly (P < 0.001) higher proportion of lung function impairment compared to those who had a higher level of education. Subjects with an office job, business, homemakers, and manual laborers were found to have a higher proportion of lung function impairment, while students and teachers had the least proportions of lung function impairment (P < 0.001). The subjects from all the socioeconomic classes were more or less found to have similar proportions of impairment of lung function. Those with a longer duration of stay in Delhi had a higher proportion of impairment of lung function with highest proportion of impairment (36.7%) in those living for >20 years (P = 0.005).
|Table 5 Risk factors of lung function impairment using univariate analysis|
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Surprisingly, smoking and secondhand exposure to smoke at home were not found to be associated with impairment of lung function. Contrary to expectation, a higher proportion of lung function impairment was found among those who were not exposed to secondhand smoke at the workplace, those who had exposure to outdoors for <2 hours per day, and those who were not exposed to dust [Table 5].
[Table 6] shows multivariate analysis. All the factors which had a P-value of ≤0.05 were included in the model for logistic regression to assess the independent predictors of lung function impairment. It was found that subjects in the age group of 31 to 40 years and 41 to 50 years had a higher risk for lung function impairment as compared to those in 21 to 30 years. The subjects with an education of higher secondary and above were found to be at a lower risk for lung function impairment as compared to those who had no formal education. Among the occupation class, students were found to have a lower risk of impairment of lung function when compared to those doing an office job.
|Table 6 Independent predictors of lung impairment by logistic regression|
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| Discussion|| |
Air pollution is a major cause of morbidity and mortality in India, with Delhi showing air quality index at very poor or severe levels. Department of Community Medicine of a Medical College in Delhi, with support from the Directorate of Health Services of the Government of National Capital Territory (GNCT) of Delhi, conducted spirometry examination of volunteers in 10 sites of Delhi. Since the examination was done in makeshift settings in which asymptomatic volunteers had participated, bronchodilator reversibility testing was not done. Spirometry examination was done by trained technicians. Interns and postgraduate student doctors conducted the interview and examination.
A total of 3019 individuals had volunteered for the study. Of them, 34.3% of the individuals were found to have some form of lung function impairment, with majority showing restrictive pattern of disorder. Univariate analysis showed that age group, occupation, and duration of stay in Delhi were significantly associated with lung function impairment. On multivariate analysis, significantly higher proportion of subjects was found to be present in higher age group, higher education status, and students.
In the study done by CPCB, reduced lung function was seen in 40.3% of study subjects. According to a study done by Wang et al. in Xi’an region of China, 19.6% of the patients had obstructive pattern. This proportion was higher than that found in our study. This could be because of sociodemographic differences between the two regions and also because of difference in exposure to air pollution.
Our study showed that the odds of lung function impairment among those >30 years were higher than that among subjects <30 years of age. This is in line with the change in pulmonary function with age. The lungs undergo a phase of growth and maturation during the first two decades of life and achieve maximal lung function around the age of 20 years in females and 25 years in males. Lung function remains steady with very minimal change from age 20 to 35 years and starts declining thereafter.
The subjects of our study with an education of higher secondary and above were found to be at a lower risk for lung function impairment as compared to those who had no formal education. This could be because education leads to better socioeconomic status and therefore the individuals may not be exposed to air pollution or may have facilities like air purifiers. The study done by CPCB found that reduced lung function was high among those from lower socioeconomic strata. Few studies done among COPD patients also have found that health-related quality of life of COPD patients was poorer among those with lesser education and lower socioeconomic status.,
In the present study, students were found to have lower odds for having lung function impaired when compared to those who do office jobs. Usually, students tend to be from younger age groups and they might stay in closed spaces, which could be the reasons for a lower proportion of lung function impairment seen among them. In the study done by CPCB, roadside hawkers and drivers were found to have a higher prevalence of reduced lung function.
In the present study, the proportion of individuals who had impaired lung function remained the same among smokers and nonsmokers. However, multiple studies have shown that smoking is a definite risk factor for COPD and other conditions that reduce lung function.,,,
Though not significant in multivariable analysis, univariate analysis in the present study showed that those who were staying in Delhi for longer duration had a higher prevalence of lung function impairment as compared to those who were staying for relatively shorter periods. Duration of stay can be considered as a proxy variable for duration of exposure to air pollution. Many studies have shown that longer duration of exposure to air pollution has adverse effects on lung function.,
In the present study, majority of the participants had used liquid petroleum gas (LPG) for cooking and hence a significant difference in lung function was not observed between those who used LPG and biomass fuel. However, in populations where biomass fuel is predominantly used, many studies have reported poor lung function.,,
Each year, 41 million people die from a noncommunicable disease that is equivalent to 71% of all deaths globally. More than 80% of these total deaths are due to four groups of diseases, which are cardiovascular diseases, cancers, respiratory diseases, and diabetes. Respiratory diseases occupy the third position with 3.9 million annual deaths. With more than one-third of the subjects of the present study having impaired lung function, this study highlights the grave condition and brings to focus the urgent need for control of air pollution.
A review by Rizwan et al. discussed the steps taken by the Government of National Capital Territory of Delhi, to reduce the level of air pollution in the city, during the last 10 years. However, as per the authors’ opinion, more need to be done and the existing measures need to be strengthened and magnified to a larger scale.
The 2030 Agenda for Sustainable Development adopted by all Member States of the United Nations in 2015, with the vision of achieving peace and prosperity for people and the planet, has identified a set of 17 Sustainable Development Goals that include measures for improving air quality. All countries are committed to achieve these goals, thereby ensuring good health and wellbeing of its population, which can be done through primary health care by systematically addressing the broader determinants of health including social, economic, environmental, as well as people’s characteristics and behaviors, through evidence-informed public policies and actions across all sectors.
Limitations of the study
Since the screening was done among volunteers in makeshift sites, it was not possible to check reversibility of obstruction by using bronchodilators. Hence, the airway obstruction obtained in the present study could be an overestimation.
| Conclusion|| |
Though spirometry is not an ideal screening test, the study does reflect the status of lung function in Delhi population where more than one-third of the study subjects were found to have impaired lung function test, with those who belonged to 31 to 50 years of age having higher odds for lung function impairment when compared to younger age groups, probably indicating the cumulative effect of air pollution.
Measures for curbing air pollution are hence the need of the hour. Along with pollution control, screening for lung function among high-risk groups would be a good way forward to detect undiagnosed cases of lung function impairment. However, further studies need to be done to assess the determinants of lung function impairment. The broader determinants of health should be addressed through evidence-informed public policies and actions across all sectors.
Authors thank Dr Tarun Seem and Dr Deepak K. Tempe for administrative support. Authors also thank various hospitals, dispensaries, and police stations for providing space to conduct the data collection and manpower; Cipla Ltd. and hospitals for providing portable spirometers and consumables for carrying out the spirometry test.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]