Overview of workers’ exposure while performing repair and maintenance work
INRS conducted two main studies regarding the exposure of maintenance workers to dangerous substances. The companies under scrutiny were large firms belonging to the oil and chemical sector. In both cases the maintenance work was contracted out to small and specialised companies.
The studies aimed at:
- Assessment of the exposure to chemical pollutants
- Study of work organisation: influence of subcontracting on exposure to chemical pollutants during maintenance works, comparison to exposure of the contracting out company’s staff
- How to improve occupational risks prevention
In case of the oil company the main operations were: unloading of catalyst, riddling, putting old catalyst in big bags, reloading, etc. It turned out that during some operations there were high exposure to cristobalite and vanadium and there were high dust concentration in the atmosphere during riddling operations.
Although the service company was specialised for the job, the equipment used by them was rarely perfectly tailored to the installations they were working on. This was one of the reasons for high exposure rates.
Sophisticated technical tasks were often performed by skilled and specialised workforce. The exposure rates were usually low. Less specific tasks (riddling, putting the old catalyst into big bags) were usually performed by unskilled contract workers. The exposure rates were sometimes very high.
There were very high difficulties for assessing and registering the occupational exposures (often to carcinogenic substances). There was a rather wide range of catalysts types from one plant to the other, some poisons: arsenic, polycyclic aromatic hydrocarbons, etc. Respiratory protective equipments was widely used, however the choice was not always appropriate. The time schedule does rarely consider the wearing of these equipments. There was one case where workers form one service company were only working one day because otherwise they would develop effects like a blue tongue. Time pressure is usually very high, because very expensive plant stops are necessary for the work. A comparison between the exposure of the workers of the hiring company and of the contractors was not possible because they generally do not perform the same type of work.
In a big chemical plant – a manufacturer of chlorine, soda, isocyanates, etc. - INRS measured the exposure of contract workers to chemicals during a six-week plant shut down for maintenance. The ca. 2000 maintenance workers were exposed to many dangerous products such as chlorine, soda, phosgene, inorganic acids, organic solvents, isocyanates, etc. Some of the workers are only there during the shutdown time others work on site during the whole year. More than 700 personal samplings were taken during the study. Most of them showed very low exposure levels, which was attributed to the fact that workers wear respiratory protective equipment and that a comprehensive risk assessment is performed in advance. However, the exposure levels tend to increase with the work progress. It happens in particular during the high-level cleaning of pipes, reactors, etc., without any lethal risk, but with significant exposure (especially to isocyanates). Collective protection is hard to design particularly for operations such as: furnace maintenance, painting of confined spaces, removal of insulating material. These operations are the most risky in terms of exposure to chemicals.
Although the preparation and supervision of maintenance operations performed by the contracting out company were exemplary, after two to three weeks after the start of the work, exposure rates increased probably due to the (unfounded) assumption that occupational risks had decreased. Security instructions were less strictly respected. It also happened that an operation was not scheduled and had to be organised at the last minute. Inadequately prepared and poorly supervised, it resulted in high exposure to chemicals. There were high time constraints experienced by maintenance teams. It was difficult to register during this long period the exposure to chemicals of the most mobile teams (workers were called to other sites and were replaced by new colleagues). Similar to the first example it is also impossible to compare the exposure of the workers from the contracting out firm and from the contractors: the tasks performed are not similar.
The speaker concluded that in cases where a hiring firm uses a subcontracting firm, a common risk assessment performed in collaboration by the two firms is the starting point for the design of a prevention plan. However the contracting out company is responsible. But each company management keeps its own responsibility regarding his staff, including the safety and security policy. The prevention plan must in particular consider the organisation of staffs, materials and working processes, it also has to organise the reception, information and training of the particular risks on the site for workers of the subcontracting firms.
The risk assessment has to be updated on a regular basis and has to consider possible changes in the plant. Because these changes may occur frequently, also the risk assessment needs to be updated frequently and it has to be established for each operation. It is possible to produce a reference document for example on a yearly basis, but a risk assessment must nevertheless always be performed just before the operation itself: work authorisation for a specific task, etc. These arrangements are also pertinent for maintenance operations performed by internal teams of maintenance. In some process industries, during some activity phases, many work authorisations are delivered during a work shift and the foreman of the contracting out company has not enough time to do a proper risk assessment for each operation.
In general INRS observed that occupational risk prevention during subcontracted maintenance activities has improved during the last years. The safety management systems, even if they are not perfect, have had the merit to put health and safety at the centre of every actor’s concerns.
However these systems are often mainly based on quantitative indicators which are in turn based on frequency of work accidents. But accident indicators are not predictive of exposure to chemicals. It is necessary to develop a specific prevention program for these. A specific monitoring program of exposure to chemicals should be implemented for the maintenance staff, because their working conditions are often very different from those of manufacturing staff and they often use specific materials which can lead to particular exposure.
The speaker pointed out that occupational risk prevention can improve only through a complete openness in work practices and with the contracting out company keeping a perfect knowledge of its premises and their work processes. There is a real security culture in large industries: it is less obvious in tertiary activities. How is the state of occupational health and safety in maintenance in office buildings?
Discussion: There were three questions asked in order to have certain aspects of the lecture explained in more detail.
The speaker stated that repair and maintenance work conditions seldom allow the use of collective protective equipment. The tasks performed make the use of personal protective equipment difficult and poorly efficient. Time constraints are strong. Most work is done by contractors. The protection of maintenance workers has to be improved greatly. Especially the collective protection should be as good as in the production line.
This statement was discussed in a roundtable discussion and with the audience after all speakers had made their speeches.Click here to hide the full text
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