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Biomedical Research

Effect of occupational exposure to dust on pulmonary function in workers associated with building demolition

Author(s): Smilee Johncy S, Ajay KT, Dhanyakumar G, Prabhu Raj N, Vivian Samuel T

Vol. 22, No. 2 (2011-04 - 2011-06)

Smilee Johncy S, Ajay KT, Dhanyakumar G, Prabhu Raj N, Vivian Samuel T٭

Department of Physiology, ٭Department of Biochemistry, J J M Medical College, Davangere, Karnataka India.

Abstract

Much occupational lung disease is associated with workers exposed to aerosols in the form of dust, fumes, gases etc. Workers engaged in demolition of buildings are at risk of develop-ing impaired lung function due to exposure to high level of dust generated. The objective of the study was to assess the effects of respirable dust on the pulmonary function in workers engaged in building demolition work in India. The pulmonary function was studied using computerized spirometer in 55 male workers associated with building demolition work in the age group of 20 to 50 years and compared with 40 age matched healthy male controls. All participants were non-smokers, matched for age, height, weight and socioeconomic sta-tus. The results were compared by unpaired’t’-test. Significant reduction in the overall mean values of FVC, FEV1, FEV1/FVC%, PEFR and FEF25-75% were observed in demolition workers compared to the matched controls. Based on the results of the present study, we conclude that the demolition workers are at an increased risk of developing occupationally related pulmonary function impairment. The results suggest that there is an urgent need to improve dust control measures and the health status of workers engaged in demolition op-erations.

Key words: Pulmonary function test, FVC, FEV1, Occupational hazards, PEFR
Accepted November 25 2010

Introduction

The building demolition environment and consequences of the health hazards encountered have received relatively little attention in the occupational medicine literature. While acute trauma has been recognized as a serious problem for demolition workers, there has been much less focus on occupational illnesses for which demolition workers may be at increased risk [1]. In construction and demolition projects, dust particles are created in a wide range of sizes. Larger, heavier particles tend to settle out of the air, while smaller, lighter solids may hang indefi-nitely. For occupational health purposes, airborne solids are categorized by size as either respirable or inhalable. Respirable dust is small enough to penetrate deep into the lungs, usually identified as particles under 10 microns in size (PM-10) [2]. The larger particles in the inhalable dust classification are typically trapped in the nose, throat or upper respiratory tract. In contrast, these tiny solids that migrate far into the respiratory system are generally be-yond the body’s natural cleaning mechanisms such as cilia and mucous membranes and are likely to be re-tained. Dust inhaled by workers can irritate airways and exacerbate conditions such as asthma or set up an in-flammatory reaction, fibrosis, leading to defective oxygen diffusion and lung function impairment [3]. Construction dust generated by securing and demolishing damaged structures, in combination with other dust exposures, can cause chronic bronchitis and emphysema [4]. Asbestos is contained in many materials used in construction like thermal insulation, fireproofing, acoustical insulation, decorative surfacing, binder in roofing papers, floor tiling and therefore potentially encountered during demolition. During the renovation or demolition of industrial, com-mercial and residential structures, these materials can be disturbed, generating aerosols of dust containing respir-able asbestos fibers and placing those on site at risk of asbestos-related disease [5]. Next is respirable crystalline silica because of its widespread appearance in nature and as a fundamental building block for structures. There is ample opportunity for exposure to crystalline silica in demolition operations [4]. Thus demolition workers are exposed to a mixture of respirable dust like asbestos, lead, silica dust, concrete, cement, stone, sand etc [6].

A cohort study in Sweden showed that there was a statis-tically significant increase in mortality from COPD among those with any airborne exposure. In a Poisson regression model, exposure to inorganic dust was associ-ated with an increased risk, especially among never-smokers. The fraction of COPD among the exposed at-tributable to any air borne exposure was estimated as 10.7% overall and 52.6% among never-smokers [7]. Community based studies have demonstrated increased relative risks for respiratory symptoms consistent with COPD as well as for excess annual declines in Forced Expiratory Volume in 1 second (FEV1) associated with occupational exposure to dust or gases [8]. Exposure to World Trade Center dust led to large declines in FEV1 for rescue workers during the first year. Overall, these de-clines were persistent, without recovery over the next 6 years, leaving a substantial proportion of workers with abnormal lung function [9]. There is growing evidence that a sizeable proportion of the burden of COPD in the developed world is attributable to workplace exposures to irritating dust, gases, fumes and smoke. In the developing world, population data are less readily available, but be-cause occupational exposures are often higher, it stands to reason that the risks are likely higher as well [10].

Pulmonary function tests are performed to assess lung function, to determine the degree of damage to the lungs, diagnosis of certain types of lung disease and to analyze whether exposure to contaminants at work affects lung function. In occupational respiratory diseases, spirometry is one of the most important diagnostic tools, most widely used, most basic and effort dependent pulmonary function test. It plays a significant role in the diagnosis and prog-nosis of these diseases and describes the effect of restric-tion or obstruction on the lung function [11]. Periodic testing in workers can detect pulmonary disease in its ear-lier stages, when corrective measures are more likely to be beneficial. Various airborne particulate dusts put the worker’s health into jeopardy and most of the workers in India do not use the protective measures. No earlier study in Indian demolition workers has been reported. Further the relationship between the pulmonary function impair-ment and duration of exposure has not been analyzed ear-lier. Hence this study was undertaken to investigate the effect of dust exposure on the lung function in building demolition workers.

Materials and Methods

The study group consisted of 55 healthy non-smoker males in the age group of 2050 years engaged in demoli-tion work, while 40 age matched healthy male non smok-ers, served as controls. All subjects were matched for age, height and weight and all were non-smokers. These work-ers worked for at least 810 hours per day and six days per week without using any self-protective measures. Subjects with clinical abnormalities of vertebral column and thoracic cage, anemia, diabetes mellitus, hyperten-sion, pulmonary tuberculosis, bronchial asthma, chronic bronchitis, emphysema and other respiratory diseases and subjects who had undergone abdominal or chest surgery were excluded from the study. An informed written con-sent was taken after explaining the procedure to the sub-ject. Spirometry was performed on a computerized RMS medspiror. The questionnaire was filled up and relevant data like name, age, height, weight etc were entered in the computer. The test module was activated and the subject was given proper instructions about the procedure to be performed. All the pulmonary function tests were done on the subjects, comfortably seated in an upright position. The subject was asked to breath in and out through the mouthpiece to familiarize himself with the equipment. During the test the subject was adequately encouraged to perform their optimum level and also a nose clip was ap-plied during the entire maneuver. The test was repeated three times after adequate rest and the results obtained were available in the spirometer. The parameters were Forced Vital Capacity (FVC), Forced Expiratory Volume in one second (FEV1), Forced Expiratory Ratio (FEV1 / FVC ), Peak Expiratory Flow Rate (PEFR) and Forced Expiratory Flow (FEF25-75).

Statistical analysis:

Statistical analysis was done using a unpaired’t’-test (two-tailed). The level of significance was established at value of P < 0.05. The overall mean pulmonary function data were also correlated against the duration of exposure. Li-near regression was applied in this correlation and the equation y = bx + c was derived with the correlation coef-ficient®, where “y” means spirometric value, “x” indi-cates years of exposure and “c” is a constant. The R2-value determined the level of the correlation significance.

Results

Anthropometric studies

Table-1 demonstrates the comparison of the anthropomet-ric parameters between the demolition workers and their matched control subjects. There was no significant differ-ence between the means of anthropometric parameters in terms of age, height and weight between the groups.

Pulmonary function test

The overall mean values of the lung function parameters for the total number of demolition workers and their matched controls are presented in Table-1. The values of FVC, FEV1, FEV1/FVC%, PEFR and FEF 2575% were significantly decreased (P < 0.001) in demolition workers as compared with their matched controls. The mean dura-tion of exposure to dust in demolition workers was 8.89 5.5(range, 118years).

Regression analysis

Regression analyses were performed on the overall mean pulmonary function data against the duration of exposure of the demolition workers. Table- 2. Significant negative correlation for the r values were found for FVC (P < 0.001), FEV1 (P < 0.001), FEV1/FVC% (P < 0. 01), PEFR (P < 0.001)and FEF 2575% (P < 0.001) as shown in Figs. 1,2,3,4,5 indicating that the increased dust exposure diminished the lung function.

Table 1. Comparison of lung function parameters between Demolition workers and controls

Parameters Demolition Workers (n=55) Control subjects (n = 40) Percentage difference (%) Significance
Mean ±SD Mean ±SD ٭t-value p-value
Age (yrs) 29.276.05 33.03±6.9 12.84 0.007 0.99 NS
Height (cm) 164.21±8.96 161.35 ±6.70 1.77 0.09 0.92NS
Weight (Kg) 61.91±6.39 61.62 5.28 0.47 0.81 0.41NS
FVC (L) 2.49±0.59 3.26±0.42 -23.6 1 3.49 <0.001HS
FEV1 (L) 2.18 ±0.48 2.76 ±0.36 -21.01 8.46 <0.001HS
FEV1/FVC (%) 79.18±6.2 85.75±1.93 -7.66 6.28 <0.001HS
PEFR (L/S) 6.87±1.50 8.18 ±0.87 -16.01 4.35 <0.001HS
FEF25-75% (L/S) 3.51±0.70 4.29 ±0.37 -18.18 6.52 <0.001HS

SD-Standard Deviation
P > 0.05, Not Significant (NS), P < 0.05, P < 0.01Significant (S),
P < 0.001, Highly Significant (HS)

Table 2. Correlation and Regression analysis between lung function parameters and duration of exposure

Relationship between Correlation
co-efficient
r- value
Regression
co-efficient (b)
P value Regression
equation (prediction of
Lung function
for duration
R2
Duration & FVC -0.93 -0.11 <0.001 FVC = -0.11 (Dur)+3.45 0.86
Duration & FEV1 -0.87 -0.08 <0.001 FEV1 = -0.08 (Dur)+2.93 0.75
Duration & FEV1/FVC% -0.42 -0.36 <0.01 FEV1/ FVC% = -0.36(Dur)+87.5 0.18
Duration & PEFR -0.70 -0.21 <0.001 PEFR = – 0.21 (Dur)+8.74 0.49
Duration & FEF 25-75% -0.62 -0.12 <0.001 FEF 25-75% = – 0.12(Dur)+4.94 0.38

Figure 1. Regression analysis of FVC against the duration of exposure to dust in building demolition workers

Fig 1

Figure 2. Regression analysis of FEV1 against the duration of exposure to dust in building demolition workers

Fig 2

Figure 3. Regression analysis of FEV1/FVC against the duration of exposure to dust in building demolition workers

Fig 3

Figure 4. Regression analysis of PEFR against the duration of exposure to dust in building demolition workers

Fig 4

Figure 5. Regression analysis of FEF 25-75% against the duration of exposure to dust in building demolition workers

Fig 5

Discussion

Demolition of aging and derelict housing is one compo-nent of redevelopment and revitalization [5]. Remodeling of buildings sometimes involves demolishing parts of existing structures to make room for new improvements. Demolition can expose workers to dangerous materials that are sometimes difficult to recognize. In many cases, even the building owner may not know these hazards are present. Workers in a demolition site may be exposed to various hazardous substances and physical agents, e.g. asbestos, lead, silica dust, concrete, cement, stone, sand, organic solvents, sewer gases, welding fumes, radiation, noise and vibration8. Asbestos dust can be generated whenever materials containing asbestos are handled or removed. Typical asbestos containing materials include sprayed asbestos coatings on steel columns, insulation materials, fire resistant walls, asbestos cement sheet, and flooring materials [12]. Silica is found in many building materials such as natural stone, brick and concrete. Break-ing, cutting, crushing or grinding this material will gener-ate dust containing crystalline silica. Exposure to exces-sive dust can cause silicosis, a disease resulting in lung problems [13]. Lead dust is caused by removing, grind-ing, or cutting materials covered with lead based paint, or from handling metallic lead [14].

The present study was undertaken to investigate the dose response of years of exposure to dust on lung function in workers associated with building demolition work in In-dia. It showed an association between pulmonary function impairment and duration of exposure. In addition, while conducting this kind of studies little consideration has been given to promising factors which affect the lung function such as age, height, weight and smoking. There-fore the study was designed to investigate the effects of airborne dusts on the lung function in non-smoking of demolition workers matched for age, height and weight.

The results of the present study showed a significant re-duction in the mean values of FVC, FEV1, FEV1/FVC% , PEFR and FEF25-75% in demolition workers as compared with their matched controls as well as directly propor-tional impairment of their lung function parameters to the duration of exposure. In addition, the percentage change for FVC -23.61 ; FEV1 -21.01; FEV1/FVC -7.66 ; PEFR -16.01; FEF 2575 % -18.18 were also noted.

While considering the pathophysiological aspects of a drop in the values of the aforesaid lung function parame-ters, FVC is decreased in pulmonary obstruction, emphy-sema, pleural effusion, pneumothorax, pulmonary edema and poliomyelitis. Similarly, the FEV1 value is low in obstructive lung diseases and in reduced lung volume [15]. The decline in FEV1 is a convenient standard against which we can measure marked declines in subjects with the history of chronic obstructive pulmonary disease (COPD) or in subjects exposed to environmental pollut-ants, whereas, PEFR provides an objective assessment of functional changes associated with environmental and occupational exposures and determines acute or chronic disease processes in patients with severe COPD. PEFR is persistently low and represents collapsing of large air-ways [15].

Masoud et al reported that FVC, FEV1 and PEFR were statistically decreased in non smoking workers exposed to asbestos and they also established that duration of expo-sure of asbestos is an important factor in the decrease of ventilatory function [12]. Becklake in his community based studies and cross sectional studies suggested that in spite of healthy workers air flow limitations can be de-tected excessively in workers in dusty workplace. In addi-tion to that longitudinal studies of various mineral dust exposure have shown excessive annual loss of lung func-tion [16]. Ohlson and coworkers investigated the effect of exposure of airborne dust in the lung function in male workers employed in asbestos cement plant for more than 10 years and found a decrease in FVC and FEV1 after ad-justment for age, height, weight and smoking category. They also concluded that lung function impairment in these workers were mainly due to obstructive changes [17]. Green et al demonstrated that individuals exposed to mixed mineral dust in early adult life had excess respi-ratory symptoms and decreased FVC and FEV1 with air-flow obstruction compared to the controls. They also con-cluded that long term exposure to mineral dust including silicia is known to cause pneumoconiosis [18]. Raymond and his colleagues analyzed the effect of exposure to sil-ica, asbestos and emphysema in workers and found that ,FVC and FEV1 are reduced in exposure group19. Krzy-zanowski and his co-workers conducted a study among workers who are exposed to dust found in building mate-rial and in pottery industry and found an annual rate of decline in FEV1 to occupational exposure to dust [20]. The terrorist attacks on the World Trade Center, exposed thousands of rescue workers to dust, leading to substantial declines in lung function in the first year. On analyzing the long-term effects of exposure, over all these declines were persistent, without recovery over the next 6 years with a mean annualized reduction in FEV1 of 25 ml per year rescue workers.

Based on the result of the present study we conclude that airborne particulate materials like asbestos, lead, silica dust, concrete, cement, stone, sand and other dusts in the demolition site adversely affect the pulmonary function parameters like FVC, FEV1, FEV1/FVC%, PEFR and FEF25-75% in the building demolition workers and cause an obstructive pattern of lung function impairment which is associated with the dose effects of years of exposure to airborne dust in demolition site.

Recommendation

Although more comprehensive, long-term prospective and specific studies are necessary, we recommend control of dust in workplace with high exposure to respirable aerosols by providing standard and appropriate protective tools (mask) for workers and periodic assessment of pul-monary function by spirometry. The following work prac-tice standards shall be followed during structure demoli-tion. The structure shall be wet with sufficient quantities of water to prevent the generation of visible dust plumes prior to removal. Wetting shall continue during active removal and the debris reduction process. Use of personal protective equipment and influencing worker behavior by training and education are also recommended.

Acknowledgement:

Authors are grateful to Dr. H.R. Chandrasekhar Principal and Mr.S.Thangaraj Thomas Asst. professor in Anatomy, J J M Medical College, Davangere for their support and encouragement, to the statistician and to all the volunteers who participated in this study.

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Correspondence to:
S. Smilee Johncy

Department of Physiology
J.J.M. Medical College, Davangere 577004
Karnataka, India.
Mobile: +91-9481360700
E-mail: smileevivian(at)yahoo.co.in

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