Millions of tonnes of grain, oilseeds and feedstuffs are loaded and unloaded at ports every year. During handling these commodities can give off large quantities of dust and the more they are handled the more dust they create. This dust, which may include contaminants such as bacteria and fungi, can have serious effects on workers’ health, particularly on the lungs; chronic effects are often permanent and disabling. The diseases caused include chronic bronchitis, occupational asthma, grain fever, farmer’s lung and pneumoconioses such as silicosis.
Dust can also cause sensitization. Early indications include irritation of the eye or nose, or skin rashes. People who become sensitized (allergic) to a dust need to avoid exposure completely.
The control of hazardous substances, including grain dust, is mandated in many countries. In the United States for example, it falls under the regulation of the U.S. Department of Labor, Occupational Safety and Health Administration (OSHA). In the European Union, European Agency for Safety and Health at Work regulations lay down minimum requirements and these are implemented into national legislation. Some E.U. member states have introduced Codes of Practice and guidelines for safe handling of biological agents, including grain.
In Britain such regulation comes under the Control of Substances Hazardous to Health regulations 1994 (COSHH) and these stringent rules provide a useful guide to industry, although national codes must be the last word. Britain’s Health and Safety Executive (HSE) advises that the most effective and reliable measures to control grain dust should be used, with personal protective equipment (PPE) relied upon only as a last resort. (See "Keeping down the dust" on page 49)
RESPIRATORY PROTECTIVE EQUIPMENT
Under COSHH, PPE may only be used as the sole method of control if it is not reasonably practicable to take any other steps to reduce exposure. Respiratory protective equipment (RPE) may be needed in addition to other control measures however, when loading or unloading dusty cargoes and particularly when trimming.
RPE must be suitable for its purpose and the wearer and be compatible with any other personal protective equipment needed. RPE must be maintained so that it works properly.
HSE says the RPE must provide adequate protection against the environment in which it is used. For example, when trimming a hold of grain using a loading shovel without a cab filter, the
driver’s short-term exposure to dust could easily be over the maximum exposure limit (MEL) permitted. A simple half-mask respirator would not be acceptable: it does not reduce exposure to as far below the maximum exposure limit as is reasonably practicable because equipment providing better protection, such as positive pressure RPE, is readily available.
Powered respirators with helmets are often used in the docks industry, particularly for operations where dust levels are likely significantly to exceed the occupational exposure limit, for example trimming holds or working on the quay close to the source of the dust.
HSE says that when providing RPE, you should ensure that: the wearer is sufficiently physically fit to cope with the demands of working with RPE; it fits well, taking into account facial characteristics – facial hair reduces the effectiveness of any RPE which relies on face seals (powered helmets or visors, air-fed hoods and blouses, or airfed suits are more suitable); equipment with full face masks is generally not suitable for people who wear glasses; it does not interfere with the demands of the job, for example, work rate and the need to move around, communicate and have good visibility; there are adequate storage arrangements for the RPE; it is kept clean and inspected each time it is used; the filters of non-disposable RPE are changed as necessary.
The maintenance of control measures is vital. This applies not only to dust extraction equipment but also to RPE and mechanical handling plant such as elevators, suction legs and grabs. All should be examined at appropriate intervals. Monitoring employee exposure to dust is also required when it is necessary to ensure that adequate control is maintained. Routine monitoring is not necessary where reliance is placed on RPE. Health surveillance is required for workers who are exposed to dusts that are respiratory sensitizers, such as grain and soy.
TRAINING AND SUPERVISION
As in all matters of health and safety, workers must be properly informed and trained: they need to know how to minimize exposure to dust, when to use respiratory protection, how to clean it, how to replace the filters and how to test that it is working properly.
It is important that they receive clear information on the nature of the substances being handled, the risks to health, the early signs of ill health, and how the controls in use should work. They need to be properly instructed on the correct procedures and use of control measures, including the setting up, adjustment and operation of handling equipment such as conveyors and grabs.
Line managers need to provide adequate supervision to ensure control measures are properly used. WG