الفهرس 
acknowledgementOnly 14 pages are availabe for public view
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Abstract
Welding is one of the industrial exposures that bears many hazards to the health of workers specially the ,respiratory system. The effects come through the inhaled fumes and gaseous ,by-products arising during welding ~erations. The welding fumes contain a mixture of oxides that differ according to the composition of welding electrode and materials to be welded. However, ,the most common oxides are Fe203’ MnO,. ZnQ, CuO, and 8i02. by-products are mainly N02 and ozone. The gaseous The aim of this work is : 1. To evaluate the work environment at the welding operations with main emphasis on welding fumes and their components (metal oxides and gaseous contaminants). 2. To study the effect of exposure to these contaminant on the respiratory system of welders as manifested by clinical, radiological and impairment in ventilatory lung functions. 3. To study the relationship between the medical findings and environmental exposures as well as with other related personal factors such as smoking habit. 4. To recommend adequate tests to be used for the future periodic medical examination of welders. The material of this work consists of 177 welders, plant A and 23 in plant B. A control group of 84 ~rkers were chosen from both plants, they were closely matched with the exposed subjects as regards age and height distribution, anthropometric and socio-economic background and smoking habits, but were not exposed to welding fumes a~’ gases. The population of the study was examined according to a special questionnaire included data as regards present, past, personal and occupational histories, clinical examination and s,Pecial investigations. Clinical examination included general examination and special examinations, investigations included X-ray picture and certain ventilatory lung functions i.e., FEV1.O’ FVC, and FEV and were carried out for the total population of the study” Environmental sampling were done in both plants for the area of work and general atmosphere, the chemicals sampled wre Fe03’ MnO, 2nO, 8i02’ N02 and ozone. At the area of work 16 samples were taken from plant A and 12 samples from plant B, while at the general atmosphere 12 and 6 samples were taken from plant A and B respectively” Results 1. Environmental Study Results of environmental sampling showed that concentration of all oxides were significantly higher in plant A than lnplant B, except for CuO and Si02’ this holds true for both area of work and general atmosphere. However, ~he mean values for all oxides were below their TLVs. As regards N02 and ozone, their concentrations were again significantly higher in plant A than in plant B for both area of work and general atmosphere and their mean concentrations were below their TLVs except for N02 at area of work in both plants. 2. Medical Study The study showed the following results: (a) The most common respi~atory complaints among welders were dyspnea (29.4), U.R.T. irritation (20.9), chronic bronchitis (20.3), cough or repeated attacks of cough (16.4) and bronchial asthma or asthmatic bronchitis (11.9). While among controls were dyspnea (5.9), U.R.T. irritation (3.6), chronic bronchitis (5.9), cough (7.1) and bronchial asthma or asthmatic bronchitis (5.9complaints except for cough and bronchial asthma as compared to plant B welders. (b) Dyspnea was of grade I and 11 only, its prevalence significantly increased with increases in duration of work and was significantly higher ~mong those with X-ray changes, all the cases of grade 11 dyspnea were seen among plant A welders. (c) Prevalence of chronic bronchitis among welders amd controls increased with increases in duration of exposure and with s~oking but the difference was statistically insignificant. A strong relationship was observed between chronic bronchitis among exposed and control subjects and impairment of pulmonary function tests. (d) Welders showed a significantly high prevalence of X-ray changes (36.2) as compared to controls (3.6). The main X-ray changes among welders were interstitial fibrosis (14.7), opacities (11.9) and emphysema (9.6) respectively, and were observed mainly among plant A workers. They were attributed to Fe203’ 8i02’ N02 and ozone. Welders with X~ray changes showed impairment of their ventilatory function tests, again the prevalence of X-ray changes increased with increases in duration of exposure, but the difference was insignificant except for opacities