A study on association between respiratory morbidity and type of work, duration of work among unorganized sector workers in Tamil Nadu

INTRODUCTION

Occupational health is an area of work in public health to promote and maintain the highest degree of physical, mental and social well-being of workers in all occupations” by WHO.¹ Globally Work-related diseases and injuries were responsible for the deaths of 1.9 million people in 2016, according to International Labour Organization (ILO).² Occupational exposure leads to an increased burden of non-malignant lung diseases in India in addition to the burden of occupational pneumoconiosis.³ Occupational lung diseases are defined as “lung diseases that are caused, aggravated, or exacerbated by exposure to dust, gases, fumes, and vapours in the workplace”.⁴ The prevalence of restrictive lung disease was higher among workers in puffed rice workers. The respiratory morbidity is positively associated with the duration of work. As the duration of work increases the prevalence of respiratory morbidity also increases.⁵ “Restrictive lung diseases are a heterogeneous set of pulmonary disorders defined by restrictive patterns on spirometry. These disorders are characterized by a reduced distensibility of the lungs and compromising lung expansion particularly with reduced total lung capacity (TLC)”.⁶ A study of air pollutant levels at Delhi metro construction sites reports alarmingly high levels of particulate matter pollution.⁷ In Tamil Nadu 70,48,529 workers including construction workers who have been registered in the e-SHRAM Portal as of 31^st March 2022.^8,9 The prevalence of respiratory morbidity varies across different sectors and the duration of work is positively associated with respiratory morbidity. However, there is a shortage of information regarding the prevalence of respiratory morbidity among workers in unorganised sectors in Tamil Nadu. This study aimed to find the prevalence of respiratory morbidity among workers in unorganised sectors and to find the association between year of work and type of work with respiratory morbidity among workers in unorganised sectors.

METHODS

It was a community based cross sectional study done in randomly selected districts of Tamil Nadu among workers in the unorganised sectors. The ethical approval for the study has been obtained from the Institutional Ethics Committee (IEC), Directorate of Public Health and Preventive Medicine, Tamil Nadu (S.No; DPHPM/SAC/2022/078). It was based on the cluster random sampling technique. One unorganised sector was considered as one cluster. The sample size calculated based on the prevalence of respiratory problems among construction workers in India as per “National Institute of Occupational Safety and Health Report” was 51.4%. Considering the level of confidence of 95%, the margin of error was 2.5%, the design effect was 1.2 and the Non-responders rate was 20%. The sample size was calculated as 2215. From the 38 districts of Tamil Nadu, 10 districts were selected by simple random technique (lottery method). From each district 20 unorganised sectors were selected based on the advanced tour programme of the labour mobile medical unit. Workers who were available on the date of the visit were included in the study. Totally 2236 workers in unorganised sectors were recruited for the study. The workers were recruited based on the inclusion and exclusion criteria. The workers included in this study were brick klin workers, ceramic and carpeting workers, cleaning workers, construction workers, drivers, engineers, fabric workers, labourers, machine operators, packing workers, painters, poultry feed making, quarry workers, securities, welders and bar benders, sweepers, clerical workers.

Study period

The study was conducted from September 2022 to October 2022.

Inclusion criteria

Male and female workers (≥18 years) employed in the unorganised sectors.

Exclusion criteria

Haemoptysis of unknown origin, history of recent myocardial infarction, acute disorders like nausea/vomiting, recent eye surgery/recent thoracic/abdominal surgical procedures, females in second and third-trimester pregnancy, upper or lower respiratory tract infection in the past three weeks, resting heart rate of more than 120 beats per minute who give consent for the study were excluded.

After obtaining the informed consent, the data collection was done using an interviewer-administered semi-structured questionnaire. The airflow and lung volumes are measured by spirometry.

Operational definition

Unorganised sectors

"Consisting of all unincorporated private enterprises owned by individuals or households engaged in the sale or production of goods and services operated on a proprietary or partnership basis and with less than ten total workers."¹⁰

Spirometry

A spirometer was used for measuring the airflow and lung volumes. It provides an objective measurement of lung function. It is a gold standard test for measuring lung function. The guidelines of the American Thoracic Society/European Respiratory Society (ATS/ERS) on pulmonary function tests were adhered to throughout the study. The following lung function parameters were recorded for analysis: 1) Forced vital capacity (FVC), 2) Forced expiratory volume at 1 second (FEV₁), 3) Ratio of FEV₁ to FVC (FEV₁/FVC), expressed as percentage (%).

Restrictive lung disease

A condition that reduces the total lung capacity, the amount of air that the lungs can hold. It is characterized by a decreased FVC (forced vital capacity), which is the volume of air that can be forcibly exhaled after a full inhalation. The FEV1/FVC ratio (the ratio of forced expiratory volume in one second to FVC) is usually normal or increased.

Obstructive lung disease

A condition that impairs the airflow out of the lungs. It is characterized by a decreased FEV1/FVC ratio, which indicates that the lungs are less efficient at exhaling air.

Respiratory morbidity

It combines both restrictive lung disease and obstructive lung disease.

Statistical analysis

The data were entered into Excel and analyzed using SPSS 21. The prevalence of respiratory morbidity was expressed as a proportion. Univariate analysis and Multi variable logistic regression was used to find the association between respiratory morbidity and type, duration of work. The Chi-square test was used to find the p value in univariate analysis. P value <0.05 was considered statistically significant.

RESULTS

As shown in Figure 1, the prevalence of respiratory morbidity was 59% among workers in the unorganised sectors. Among them, the prevalence of restrictive lung disease (55%, n=1223) was higher than obstructive lung disease (4%, n=90).

Table 1 shows that based on univariate analysis male sex, <5 years of work, smokers, brick klin workers, construction workers, labourers, cleaning workers quarry workers and labourers were found to be risk factors for developing respiratory morbidity People employed in fabric working, poultry feed making and securities were found to have no risk for respiratory morbidity. The regular mask usage was found to be a protective factors for respiratory morbidity.

After adjusting to other variables using multivariable analysis brick klin workers, construction workers, cleaning workers, labourers and quarry workers were found to be risk for developing respiratory morbidity. People employed in machine operation and poultry feed making were found to have no risk for respiratory morbidity. Regular mask usage was found to be protective factors. The R²_Negalkerke=0.164, i.e. 16.4% variability in the dependent variable can be predicted by the independent variables. The overall p value <0.001.

Table 3 shows that workers with less than 5 years of work had higher risk of developing restrictive lung disease (OR=1.76, p=0.009) than workers with years of work more than 5 years.

DISCUSSION

In this present study, more than half of the workers suffer from respiratory morbidity (both obstructive and restrictive). Similar results were found in a study done by Muntazeem et al, Jani et al.^5,11 The prevalence of restrictive lung disease (54.7%) was higher among the unorganised sector workers than obstructive lung disease (41.0%). Similar results were found by Muntazeem et al, Tawade et al and a case study was done by the Energy Research Institute, Bangalore.^5,12,13 In this study respiratory morbidity was positively associated with duration of work. Similar results were found by Rana et al, Ajeel et al, Prakash et al.^14-16 The risk of respiratory morbidity was high among workers with a duration of work less than 5 years (1.3, p=0.001) and also risk of restrictive lung disease was high among workers with a duration of work less than 5 years (OR = 1.76, p=0.001) which was not similar to the study done by Muntazeem et al.⁵ The respiratory morbidity occurs within 5 years of joining work in unorganised sectors which was against our general expectations and the reason for early occurrence could be high level of occupational exposure, long duration of work per day, personal habits like smoking, nutritional status, co-morbidities and also workers leaving their job at an earlier period due to respiratory symptoms which will have to exploded further by qualitative studies. Workers with regular mask usage had a lower risk (OR=0.57, p<0.001) of respiratory morbidity which was similar to the study done by Okoffo et al.¹⁷ In the present study risk for respiratory morbidity was higher among quarry workers (OR = 9.489 with p-value <0.001) which was similar to the study done by Ahadzi et al.¹⁸ The high respiratory morbidity among quarry workers was due to exposure to silica dust exposure. Next to Quarry workers, brick klin workers (OR = 7.67 with p value <0.001) had a higher risk of respiratory morbidity. This was because clay dust contains a mixture of inorganic compounds like magnesium compounds, free silica, various organic materials.¹⁹ The Construction workers had (OR=2.5, p<0.001) higher risk of having respiratory morbidity. This was due to exposure to cement dust, a wide range of inorganic respiratory allergens and welding fumes.²⁰ The above results show that occupations with exposure to dust, fumes, and silica had a higher risk of respiratory morbidity, particularly restrictive lung disease in a shorter duration of work. In Tamil Nadu unorganised sector workforce constitutes 93% of the total workforce. They introduced 50 mobile health clinics for screening workers in unorganised sectors.²¹ Even though they are working efficiently there should be a programme for screening workers before joining work and also screening to be started as early as possible. Both the Factories Act, 1948 and the Atomic Energy (Factories) Rules, 1996 have provisions for the use of appropriate types of personal protective equipment.²² The practice of using personal protective equipment was low among workers. Hence proper education about the usage of personal protective equipment is to be done among workers.

This study has few limitations. It is a cross-sectional study, so prospective studies to be done further to find the early onset of disease and other risk factors. The follow-up study to be done on restrictive lung disease patient after 5 years to know their status.

CONCLUSION

The prevalence of restrictive lung diseases was high among the study population. The risk for respiratory morbidity was high among occupations with dust exposure. Wearing a mask had a protection towards the development of respiratory morbidity. This study shows that restrictive lung disease occurs within 5 years of work, hence periodic screening and proper safety measures should be advocated from the early days of joining the workplace.

Funding: No funding sources

Conflict of interest: None declared

Ethical approval: The study was approved by the Institutional Ethics Committee

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