SAMPLING OF AEROSOL AT WORKSITE OF AN INDUSTRY IN NORWAY

A study project performed in 2001 in Bergen, Norway

Introduction:

The term "aerosol" is defined as a dispersed system of solid or liquid particles suspended in a gas, most commonly air. In a workplace, it applies to a wide range of particle clouds including compact mineral and metallic particles produced in the process and the manufacturing industries, agglomerated particles found in the fumes during welding, metal smelting etc., fibre particles such as asbestos and man made mineral fibres produced for insulation purposes, droplets from electroplating processes and cutting oils.

For the sampling of aerosol at the work site, a construction industry located near Bergen called ******** Industry was visited. This industry has own Occupational Health Service and has regular health check up of the employees. The main work or production of this industry is the construction of drilling and cargo handling equipment, which has widely been used through out the country. The major part of the work consists of sawing, breaking, grinding, scissoring, welding etc. of metals. In this industry, steel S355J2G3 is widely used for the construction purposes. Material data sheet of this steel reveals it''s contains of C, Mn, P, S, Cr, Si, Cu, V and Mo. A special electrode containing C, Mn, Si, P and S is used for arc welding. Sometime during the process of welding, a shielding gas is used which contains Argon 92%, Co2 8% and NO 0.03%.

The survey of the working area reveals that it consists of a big room of size approximately 150m*50m*20m. The ventilation system was a long general exhaust system over the ceiling. No local exhaust system was noted. There is a big outlet to the external area that keeps on almost open. The use of proper personal protective equipment was not seen in all workers. All workers were using ear bud and only those doing welding were wearing mask and protective glasses. One of the study subjects, doing welding was welding respiratory protective equipment.
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Methods:
The study was performed by the master students from the Section of occupational medicine, University of Bergen along with their supervisor Dr. Magne Bråtveit. It was a regular working day and the personal exposure to the aerosols was similar to other days.

The whole day 2 personal and 1 stationary measurement were done using pump no. 55, 470 and 471 connected to the cassettes with different filters respectively. All pumps were calibrated in the X-Lab. The flow rates of the pumps were noted with the help of a flow meter no. 1 at the beginning and end of the measurements. Similarly the exact time of the measurements were also noted. A pump was kept at the corner of the working place (at an approximate height of 5 ft.) for the stationary measurement of the aerosols. Two personal exposure measurement sampling was done. One cassette was inserted inside the respiratory protective equipment of the worker doing welding and another was usual personal measurement.

There were no special inclusion criteria for the workers for study. Two workers with potential exposure to hazardous aerosols, one doing welding with respiratory protective equipment and another doing cutting and grinding of metal without any PPE were included in the study.

The calculation of the total dust and the elements were done in the X-Lab with the help of gravimetry and atomic absorption spectrometry respectively.
------------------------------------------------------------------------------Results:
The results from the whole day personal and stationary measurements are given in table 1 and 2. Table 1 shows the level of the total dust in the measured three samples. Sample 1 means the measurement of the worker with out any PPE and is 7.87mg/ cu.m, which is much higher than the Norwegian occupational exposure limit of 5mg/cu.m for the total dust with welding fume. The value for the measurement for the sample 2(worker doing welding) and stationary was within the Norwegian occupational exposure limit.

Table 1.
Samples Results Norwegian OEL
Personal 1 (without PPE) 7.87 mg/cu.m 5 mg/cu.m
Personal 2(with PPE) 1.26mg/cu.m 5 mg/cu.m
Stationary 2.79 mg/cu.m 5 mg/cu.m


Previous measurements for the aerosol were done on 14th and 15th of August 2000 and the results of the personal measurements were 10.55 mg/cu.m and 5.66 mg/cu.m. The measurement that we have done now reveals the presence of aerosols in the working area less than in the previous measurements.

Table 2.
Elements Sample1(stationary) Sample2(Inside the PPE) Norwegian OEL
Iron (Fe) 0.74Mg/cu.m 0.642 Mg/cu.m 3.0 Mg/cu.m
Manganese(Mn) 0.08 0.072 1.0


Table 2 shows the values of different elements like iron and manganese in the total dust. The results are within the Norwegian occupational exposure limit. The measurement of elements could not be found in the previous measurement, so the comparison could not be done.
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Discussion/conclusions:

The result of these measurements showed that working in construction industry can entail the exposure to total dust up to and above the Norwegian OEL.

At this level of total dust, there is risk of adverse health effect. Health hazards associated with very high level of dust and other elements in the working environment may be the following:

· Lung diseases
1. Fibrosis
2. Bronchitis
3. Asthma
4. Cancer
· Systemic reactions
· Metal fume fever
· Allergic and sensitization reactions
· Irritations
· Bacterial and fungal infections

In such industries with high exposure to the aerosols, it is always risky to work with out proper personal protective equipment. Most of the workers in that industry were not following the proper safety measures.

Proposals for control measures:

1. Engineering / administrative controls
· Improvement in exhaust system, i.e. local exhaust system
· Proper use of PPE
· Use of less harmful metals
· Regular change of work shift
2. Follow up measurements
3. Health control of workers

Dr. Sunil Kumar Joshi
Occupational and Environmental Medicine Specialist
Asst. Professor of Community Medicine,
Kathmandu Medical College, Sinamangal