AN ANALYSIS OFDYNAMIC PULMONARY FUNCTION IN AUTOMOBILE MECHANICS

Automobile mechanics are exposed to organic and inorganic substances present in petrol and diesel. Chronic cough, wheezing and breathlessness have been reported in automobile mechanics. However there is limited published data regarding the dynamic pulmonary function test abnormalities in automobile mechanics. Hence we undertook this study. We studied the dynamic pulmonary function test abnormalities in a group of automobile mechanics. This study was conducted in a motor vehicle showroom in Mangalore.70 employees between the age group 30 to 40 years who were working as mechanics for more than one year without any pre existing lung disease were included as case group in the study. 70 employees of the same age group of the same company were taken as control group. Control group used to work in their showroom in an air conditioned environment and were not exposed to any dust and fumes. Employees who had per-existing lung diseases, smokers who had chest wall deformities, neuromuscular disease, severe obesity, previous thoracic surgery were excluded from the study. Spirometry was performed after informed consent in all these subjects. FEV1, FVC, FEV1/FVC ratio, PEFR, FEF 25-75 was recorded and compared with normal predicted value. Out of 70 subjects 12(17.14%) had restrictive lung disease among whom 4 were moderate and 8 were mild restrictive lung disease.FEF 25 -75 was decreased in 6 subjects(8.57%) out of whom 1 was moderate and 5 were mild. Dynamic pulmonary function test abnormalities in automobile mechanics include restrictive lung disease and small airways obstruction.


Introduction
Rapid industrialisation, urbanisation, use of motor vehicles, nuclear energy program are the major causes of environmental pollution in the world. Experimental studies indicate that airborne contaminants lead to injury to airways and lung parenchyma in subjects who are exposed to it 1,2 . Lungs are the target for adverse effects of noxious gases due to air pollution. The human lungs receive approximately 6-8litres of air per minute 3 .Airborne contaminants include Nitric oxide (NO 2 ), Carbon monoxide (CO), Carbon dioxide(CO 2 ), Ozone (O 3 ) Sulphur dioxide (SO 2 ), Hydrocarbons and Suspended particulate matters(SPM). They cause harmful effect on airways and lung parenchyma causing bronchoconstriction, increased mucous secretion and increased alveolar swelling. Exposure to Nitric oxide fumes may results in acute pulmonary oedema 4 . Prolonged exposure to air pollution causes bronchoconstriction, mucosal irritation and alveolar swelling leading to obstructive and restrictive disorders of lungs 5 . Numerous epidemiological studies have documented decrements in pulmonary function and various other health problems due to longterm air pollution exposure [6][7][8][9] . Health problems posed by the pollutants at the work environment of an individual are closely linked to the nature and level of exposure to these hazardous chemicals. Diesel exhaust is a major respiratory hazard for workers exposed to it in enclosed space 10 . Diesel exhaust in addition to generating pollutants like hydrocarbons, oxides of nitrogen and carbon is a major contributor to particulate matter in most places of the world. Symptoms like chronic cough, wheezing and breathlessness have been reported on exposure to these pollutants 8 . At high ambient concentrations of pollutants, well defined and marked pulmonary inflammatory response occurs 11 . Various occupational exposures to petrol /diesel exhausts have been shown to affect different organ systems of the body [12][13][14][15] . Several animal studies have also demonstrated a consistent association between the air pollutants and the altered lung function [16][17][18] . Automobile mechanics are continuously exposed to the airborne substances present in the petrol and diesel. The average duration of daily exposure to these chemicals in automobile mechanics in India generally exceeds about 8 hrs/day. The present study aims to evaluate the dynamic pulmonary function test abnormalities in automobile mechanics continuously exposed to petrol/ diesel vapour every day for more than one year in a major automobile service workshop in South India.

Material and Methods
Seventy automobile mechanics in the age group of 20 to 40 years, with no previous history of respiratory disease and minimum one year exposure to automobile exhaust in the workplace were included in the study along with seventy age matched controls who were working in air conditioned environment and were not exposed to any dust and fumes. Workers with any pre-existing respiratory diseases, history of smoking and alcohol consumption; chest wall deformities, any neuromuscular diseases, uncooperative Subjects, previous thoracic Surgery, Severe Obesity (BMI >30) and history of Pulmonary Tuberculosis were excluded from the study. A detailed history of both groups was taken. Relevant past history, family history, any drug history, personal history like smoking, alcoholism and occupational history was taken. General physical examination, vital signs were recorded. A complete spirogram was performed after informed consent.

Statistics
Statistical analysis was done by using Student's unpaired't' test. P value was taken as significant at 5 percent confidence level (p < 0.05). Airways with internal diameters of less than 2 mm are known as small airways. FEF 25-75 is reduced at low lung volumes both in restrictive and obstructive diseases. Small airway disease was present in 8.57% of cases, none in the control group in our study. Particles generated from diesel exhaust are extremely small. These small sized particles, by virtue of their greater surface area to mass ratio, can carry a much larger fraction of toxic compounds, such as hydrocarbons and metals on their surface 21 . Because of the small size, they are more likely to reach the small airways to cause small airway disease. Importantly, they can remain airborne for long periods of time and deposit in greater numbers and deeper into the lungs than larger sized particle 22 .Therefore future study could be extended to evaluate status of alveolocapillary membrane, by determining lung diffusion capacities in these workers. FEF25-75 is considered a fairly good test to identify early small airway disease. The findings of the present study indicate that small airways probably bear the brunt of the air pollution and fuel vapour related lung injury. This finding is in agreement with most studies on pollution inflicted changes in lung function 23 26 .

Results
In order to prevent lung damage among automobile mechanics, we suggest that pre employment Check-up and periodic medical check-up should be performed which should include pulmonary function test. Early identification of the workers who develop pulmonary function abnormalities will help in preventing further exposure. Awareness of the sources of air pollution in the community would help individuals avoid them. The development of appropriate equipment for monitoring and testing for environmental elements in the community and in workers would be beneficial.
Researcher's effort should be increased to identify genetic and other factors that predispose workers to environmental agents and to assess the health impacts among them. Further long term prospective studies of automobile mechanics and garage workers will help us get a more comprehensive picture of long term effects of these pollutants as the present study would serve as a bench mark.