3. Handling, use and storage of hazardous substances

When hazardous substances are used in a manufacturing enterprise, they may be handled by a number of workers. The workers may have no idea of the nature of these substances or of the dangers they may present. Appropriate precautions must be taken during handling, use and storage of such substances.

Substances vary in their dangerous properties according to the chemical composition, physical state and the conditions under which they are handled, used or stored. There is no uniform system to take into account all these different conditions. Therefore it is essential that each operation considered hazardous should be conducted strictly in accordance with approved procedures. Only designated equipment should be used. Supervisors should specify operations which are considered hazardous and require monitoring by approved safety or other personnel.

The required procedures for preventing hazards from these substances must be applied on a regular basis. These procedures are not necessarily expensive. It is important to involve all the supervisors and workers concerned. For example, supervisors should ensure that hazardous operations are conducted only in designated areas and monitored for compliance with safety rules. Only essential personnel should be permitted during a specific operation. All designated areas should have suitable warnings. Open flames or unprotected electrical equipment should not be permitted in areas where flammable or explosive materials are present. Furthermore, escape routes, exits and stairways should be clearly marked, and emergency lighting provided.

In addition to the above-mentioned precautions, the use of dangerous materials often requires appropriate protective equipment and the provision of appropriate first-aid equipment. Proper maintenance of the equipment is important. Adequate and regular training of personnel on the use of such equipment and on actions to be taken in time of danger must be organised.

As for storage of hazardous materials, the responsibility should be entrusted to one or a few persons with adequate knowledge and competence. Deposits and withdrawals should be carefully and promptly filled in a register, and signed by the recipients. Whenever possible, hazardous raw materials should be kept locked away. Inventories should be conducted at regular intervals. Flammable or explosive substances should be kept away from open flames or excessive temperatures. In addition, all the materials should be properly labelled, describing their nature, with adequate warning signs. Such labels should be in the language understood by the workers.

Obviously, the more hazardous the substance, the greater the precautions to be taken. The examples which follow illustrate some of the precautions which are feasible for small enterprises. They show how the handling, use and storage of hazardous substances can be made safe and convenient.

Some of these examples show that it is better to enclose a hazardous process than to provide personal protective devices for workers. Personal protective devices, such as goggles, masks, aprons, gloves and boots, are often uncomfortable, especially in a tropical climate. As a result, workers tend not to use them. In addition, personal protective devices must fit everyone well to be effective.

It is important that the workers are carefully trained and the process continuously monitored for safety and efficiency. It is not sufficient to merely introduce an improvement. It must work in the long term and workers have to be thoroughly trained. Finally, most of these examples clearly show that productivity and safety often go together.

Case 54: Prevention of chemicals spillage using container holders

In a toy factory in Singapore, spillage of chemicals was a frequent occurrence. Some of these chemicals were irritating to the skin and eyes. The spillages occurred mainly because the containers were not secured to the tops of the work tables. When the worker got up or sat down, he sometimes knocked against the table, and tipped over the container.

The problem was solved by using a glass container with a magnet at the bottom. The container was placed over a slab of heavy and thick steel. This measure avoided tipping over of the container even if the worktable was shaken.

Each glass bottle and magnet cost less than US$ 5. The metal slabs cost nothing, as they were made from the waste materials in the company itself.

The results were gratifying, as no chemical spillages have occurred since the introduction of this simple innovation.

Figure 86: The bottom of a glass container holder. The magnet in the bottom is placed over a steel slab.

Figure 87: A chemical container placed in a holder.

Case 55: Dust suppression by water sprinkling

In a rock crushing enterprise in Sri Lanka which employed 25 workers, there were frequent complaints of difficulty in breathing and eye irritation from the dust. A piping extension from the main water supply was installed to sprinkle water during the crushing process. Complaints from workers were reduced and morale improved as workers were no longer covered with dust.

It should be noted in this instance that the measure was introduced largely because of the complaints of discomfort by the workers. The usual dust from rock crushing has a high silica content, which can give lead to a severe lung disease called silicosis. The reduction of dust by the sprinkling of water was therefore helpful, both in reducing the discomfort of workers and a serious threat to their health at the same time.

Case 56: Suppression of tapioca dust by using a funnel

In a packing plant in Thailand, tapioca powder is re-packed from large sacks into smaller packets for retail sales. During this process, the workers breathed in large amounts of tapioca dust and experienced congestion of the chest and difficulty in breathing. Face masks were provided but the workers did not like using them in the hot, humid conditions of the factory.

Gunny sacks, which are very commonly used in tropical countries, were stitched together to form a funnel for pouring the powder from the large to the small containers. To maintain the quality of newly-packed tapioca flour, fresh gunny sacks were used for this purpose every day.

Figure 88: A funnel to suppress tapioca dust.

There were no further complaints by the workers, as the amount of dust was greatly reduced by this method. There was virtually no cost, as the gunny sacks were available free of charge. Labour for sewing might cost US$ 1 per day.

Case 57: Improved hoods for coal smoke

Workers in a blacksmith shop of a large engineering factory in Burma were exposed to smoke from furnaces. They complained of discomfort due to breathing the smoke. There was a hood over each of the furnaces, but apparently the shape and position of these hoods were inadequate and allowed much of the smoke to escape.

Figure 89: One of the old hoods leading to a chimney over a small coal furnace.

After examining the design of the existing hoods, the normal work position of the workers and the air flow through the chimneys, it was decided to replace the hoods by a better design with a larger volume. A somewhat better hood at the joint with the chimney was also found to be defective, and allowed the smoke to pass through the breathing space of workers. The height of the lower tip of the new hoods was fixed at 60 cm from the furnace tables which were set at 65 cm from the ground. These heights were found suitable for the type of work done. The furnace table was extended to the front by about 30 cm.

Figure 90: A somewhat improved hood still found defective.

Approximately US$ 13 was spent per hood for the material. The labour cost was not estimated as the factory staff were engaged in producing improved designs. Using the new hoods, the coal smoke did not escape from the canopy under normal circumstances.

Figure 91: The improved hood with larger volume, positioned so that the worker can keep away from the smoke.

Case 58: Prevention of acid burns by enclosure

In a small factory making electrical components in the Philippines, copper materials were dipped in a bath of strong acid. Workers wearing face masks had to dip wire cages filled with copper materials into the bath. The work area of this section was about 20 square metres. It was decided to improve productivity by speeding up the process. At the same time, measures were taken to increase safety during the operation.

Figure 92: A worker dipping the wire cage containing copper components into the open acid bath.

The plant manager engaged a consultancy institute, which constructed an enclosure for the acid bath. This enclosure had glass windows to enable the worker to see the process. The workers were all trained in operating the chamber. For the next three months, the chamber operation was monitored daily for effectiveness and safety.

Figure 93: Enclosed acid bath with operation from behind the glass window.

This new method increased productivity by 53 per cent because the six stations of the chamber allowed six batches of parts to be treated simultaneously instead of one by one, as done previously. Moreover, the workers were no longer exposed to the hazards of acid fumes and burns. Fatigue was reduced as the lifting, dipping and hauling up of the wire cages were all done mechanically and not manually as before. Better industrial relations resulted as the workers appreciated the improvements.

About US$ 350 were spent to construct the steel chamber, including the exhaust fans and other mechanical parts. The design and installation were done by the engineering department of the company while the consultancy service was provided free of charge. The training cost consisted of an hour's pay (US$ 0.80) for each of the workers trained, since one hour was sufficient for the training. The recurrent cost for the upkeep of the chamber was estimated at US$ 100 per year.

Savings were considerable, namely, the cost of medical treatment (including hospital charges) for workers who suffered acid burns from the previous process. The 53 per cent increase in productivity also presented significant savings.