GRAINDUSTPOSESREAL RISKSFORUNWARY
GRAINDUSTPOSESREAL RISKSFORUNWARY
Grain dust can sometimes
seem an innocent enough
part of the farmers
working life, but its
actually a major cause
of occupational asthma.
David Cousins looks
at the possible cures.
GRAIN dust has always been so much part and parcel of harvest-time, we tend not to think of it as anything sinister. OK, so it tends to billow around when you open the combine door, and sometimes you forget to grab a mask when youre cleaning out the grain store pre-harvest. Its unpleasant, certainly, and it makes you cough a bit. But its not going to do you any harm, surely?
The answer – regrettably – is yes, it is. Incidences of farmers lung may be on the decline, thanks largely to a sharp reduction in the amount of manual handling of damp hay and damp feed, but the dangers to farmers and their staff from grain dust are probably greater than ever.
What is concerning the HSE is the increasing amount of occupational asthma caused by grain dust. Farmers and their staff may be more likely to use dust masks than they used to, but there is still a good deal of ignorance about the seriousness of exposure to grain dust and the best ways of reducing it.
Nottingham-based HSE principal inspector Graeme Walker deals with all aspects of health and safety in farming, but respiratory problems caused by grain dust is one that is particularly worrying. Here he gives some answers to commonly-asked questions.
Why is grain dust so dangerous?
One type of dust can seem much like another, but the truth is that grain dust is likely to be contaminated with varying amounts of the following nasties: storage mite or weevil faeces, fungal spores, mouldy vegetable matter and bird droppings.
Any one of these can trigger an allergic reaction in the respiratory system. Once this reaction has taken place, any further exposure to the substance (even a very small one) can produce symptoms.
The symptoms are a runny or stuffy nose (rhinitis) and attacks of coughing, wheezing and chest tightness (asthma). Once people are sensitised, exposure to the substance can cause symptoms that last for several hours, if not days. In extreme cases it can cause death.
As well as asthma, exposure to grain dust can cause bronchitis, chronic obstructive lung disease, farmers lung or grain fever (a short-lived flu-like illness).
How much dust do you have to be exposed to for your health to be endangered?
This varies from individual to individual. Some people can be exposed to grain dust all their lives and suffer no ill-effects; others can find they develop asthma relatively late in their working lives. Equally, some people can find that just a few hours of exposure can bring on occupational asthma. Once you are sensitised, though, you tend to be sensitised for life.
"Its very unpredictable," says Graeme Walker. "As with other forms of asthma, its impossible to identify who might be adversely affected."
Are incidences of occupational asthma in farming on the increase?
A lack of reliable historical data makes it hard to know precisely, says Mr Walker. Added to that is the fact that asthma is increasing across the population generally, especially among children. However, it does seem to be on the rise, probably because of the fact that farms are now bigger and each person is likely to be handling more grain than he did 10 or 20 years ago. So exposure is greater.
Does farming have a worse record on this than other industries?
The short answer is yes, but thats largely because its much easier to pipe away dangerous dust in a factory or workshop than it is on a farm. You may be able to make the grain store dust-free, but out in the field its rather more difficult.
Exactly how bad farming is on this score compared to other industries is hard to ascertain, says Mr Walker, because most data on incidences of respiratory diseases isnt broken down by occupation. Also, what looks on paper like an increase in incidence of a particular disease may have come about because it is being reported more widely rather than any actual rise in cases.
However, figures from the Surveillance of Work-related and Occupational Respiratory Disease (SWORD) scheme in 1997 suggested that the rate of occupational asthma per 100,000 employees in farming, forestry and fishing was up to four times that in other industries.
What is a safe level of dust?
In an ideal world, farmers and their staff would have no exposure to dust at all. Because that is currently impractical, if not impossible, to achieve, the HSE sets a Maximum Exposure Limit (OEL). This is not a safe level, but the maximum concentration to which an employee may be exposed. For grain dust, the figure is 10mg/cu m.
Which are the worst jobs for exposure to dust?
It obviously varies from farm to farm. But a recent study of dust levels for different jobs came up with the following, rather chilling, figures. Bear in mind that the maximum exposure limits (see above right) is 10mg/cu m.
The huge range of values for a single operation illustrate the differences between one farm and another, or indeed one day and another. Someone corn-carting with a cabless tractor, for instance, with the wind in their direction will be on the receiving end of vastly more dust than someone in a modern cabbed tractor with dust blowing away from him.
What is the best way to reduce the problem?
The HSE says the first goal should be to separate the dust from the workers. Primarily, that means finding mechanical or engineering ways of removing the dust before the worker can breathe it in – or else minimising the time the operator spends in a dusty environment. This can be more difficult in some situations than in others, but that shouldnt be taken as an excuse for doing nothing.
Much of the equipment used to reduce dust is simple and therefore not too expensive, says Mr Walker. Equally, much of the advice is common-sense.
Combining and corn-carting
• If you are using a combine without a cab, consider investing in one with a cab. If financial pressures make that impossible, consider using a contractor for combining.
• Use tractors with cabs and air filtration systems for corn-carting.
• Use a dust sleeve over the end of the unloading auger to minimise the amount of dust produced during unloading.
Tipping grain into pits or onto on-floor stores.
• Ensure the operator stays in the tractor cab or out of the way of the dust as much as possible while the trailer is tipping.
• Try to fit baffles, screens or extraction equipment to stop the dust rising out of the top of the grain pit and getting into the rest of the grain store.
Moving grain about in a grain store
• Fit covers over conveyors
• Cover holes in elevators or conveyors – as well as the points where the two join – to prevent the dust escaping into the grain store
• Position fixed or portable dust extraction equipment at those points where dust is difficult to suppress (see section on equipment).
• Check that all extraction fans effectively remove dust.
• Use materials-handling equipment fitted with cabs to move grain in on-floor stores. Consider taking out of use equipment that causes high levels of dust that cannot be reduced by engineering changes.
Cleaning and dressing grain
• Try to screen equipment to prevent dust spreading into other parts of the store.
• Use an industrial vacuum cleaner to keep equipment and surrounding areas dust-free.
Milling and mixing dry grain
• Changing to an enclosed self-feed system running with some automatic controls will avoid constant attention and minimise the time that staff are exposed to dust.
• Try to fit sleeves, baffles or screens to prevent dust escaping into other parts of the building.
• Check that dust bags dont have holes in them that will allow dust to escape.
• Use an industrial vacuum cleaner to keep the area dust-free.
Cleaning up in grain stores
• Try to avoid creating vast dust clouds when you clean the grain store. Instead of sweeping or blowing with an air-line, use an industrial vacuum cleaner to clean ledges, floors, bins, etc.
• Investigate all causes of damp which may cause dust or spilt grain to become mouldy.
• Use portable dust extraction equipment when cleaning out grain bins.
Feeding dry milled grain
• Changing to a wet feed system will reduce the amount of dust produced.
• Using a less dusty feed, eg cubes or nuts, or using dust suppressant like molasses mixed into the feed will also help.
Is a disposable dust mask a good substitute?
Maybe, but thats not quite the point. The HSE says disposable dust masks should be used as a last resort in keeping operators away from dust, not a first line of defence. Use the engineering solutions outlined above to keep dust out of the grain store, it says, and only if you cant do that fall back on masks or respirators.
In practice, though, masks are often the only means of protection used by farmers and their staff. And while Mr Walker concedes that the wider use of masks in recent years has helped protect the health of those concerned, users shouldnt put too much reliance on them.
Will a standard nuisance mask do an effective job?
Definitely not. The bulk of the lung-damaging particles in grain dust will sail with ease through the relatively coarse mesh, especially the very small particles that get deep into the lungs and cause most harm. Also, because a nuisance mask feels much like a proper dust mask, it can give a false sense of security.
How do you know if a dust mask is up to the job?
Not always that easily. A glance at the disposable masks hanging up on the wall of your local tractor dealer or DIY store will reveal a mass of different code numbers and recommended usages. Some will claim to protect against dust from grinders and drills, others against fine wood dust. There may well be no mention of grain dust.
The simplest thing is to look for a disposable that meets the BS EN149 standard, or a half-mask respirator that meets BS EN140 with particle filters to BS EN143. Choose carefully and if in doubt consult a supplier who seems to know what hes talking about.
How many times can you use a disposable mask before it is no longer doing a useful job?
The short answer is once. However, there is a widespread (and largely misplaced) view in farming that you can use a mask several times and still get useful protection from it. Common sense should prevail; if you use a mask for five minutes in light dust conditions, there is probably still some life in it. However, as Mr Walker points out, many farmers and their staff go to extremes.
"Weve all seen it, the filthy dust mask hanging on a nail in the grain store gathering dust. You suddenly need a mask, there isnt a clean one around, so you grab the dirty one. The moment you put it on again you get a massive intake of accumulated dust that probably undoes all the good done by wearing a clean mask for the previous three hours!"
Also, in very dusty conditions, the performance of the mask may deteriorate more quickly than you expect. The upshot of all this? Keep a ready supply of clean masks, store them out of the dust and ditch them promptly when theyre dirty.
Dust masks arent exactly comfortable things to wear. Is there a more pleasant alternative?
Yes, fit proper dust extraction equipment, cover up conveyors and elevators and look at ways of stopping dust getting into the main part of the grain store from bins and grain reception pits (see above).
Mr Walker points out that the unpleasantness of wearing dust masks for any length of time often contributes to their ineffectiveness. Users having to wear them for long periods of time, particularly in hot conditions, are tempted to loosen them, letting in the dust.
The quality of fit is often overlooked too. If the mask shifts or puckers when you turn your head, it is breaking the seal and not doing its job. If you have a moustache or beard, its performance is going to be reduced anyway.
Harvest-time, and the dust flies. Are you keeping it out of your lungs, though?
WHAT ABOUT COSHH?
Grain dust is a hazardous substance as defined by the Control of Substances Hazardous to Health regulations 1994 (COSHH). These specify that a person at work must not be exposed to 10mg/cu m or more of grain dust averaged over eight hours.
The COSH* regulations require employers and the self-employed to:
• Assess the risk to health from work activities that involve a hazardous substance.
• Prevent, or where this is not reasonably practicable, adequately control exposure to hazardous substances.
• Introduce and maintain control measures.
• Inform and train employees about the risks and precautions to be taken.
It is also good practice to involve employees in a risk assessment – they often have personal experience of the processes that create grain dust and may be able to offer common-sense solutions to reducing exposure to it. Employees must co-operate with their employer on matters of health and safety.
Left: Disposable dust masks may give adequate protection, but they should be a last resort, says the HSE. Above: Tipping grain into the reception pit produces a lot of dust.
HEALTH SURVEILLANCE
COSH* requires employers to provide adequate health surveillance for all employees who are exposed to grain dust unless their COSH* assessment has shown that there is unlikely to be a risk of sensitisation under the conditions of use.
This means that employers should:
• Find out about employees past and present respiratory symptoms (for the purposes of gaining baseline information only), preferably by way of an examination by an occupational health professional.
• Tell employees what symptoms to look out for and advise them to report any symptoms to a responsible person.
• Regularly ask employees to fill out a questionnaire about respiratory symptoms. This should be given to new employees at six and 12 weeks after starting work and then every year. The questionnaires can be given out and checked by a "responsible person" trained by an occupational health nurse or doctor, who can also advise on the content of the questionnaire.
• Depending on the degree of risk, consider providing regular examinations for staff carried out by an occupational health nurse or doctor.
Occupational asthma resulting from work involving grain dust is, if confirmed by a doctor, a reportable disease under the 1995 RIDDOR regs (Reporting of Injuries, Diseases and Dangerous Occurrences Regulations).
• Activity Exposure level (mg/cu m)
• Combining without a cab 18-41
• Combining with a cab (plus clean cab filter) 0.2-2.5
• Grain carting 1-40
• Grain drying 4-57
• Milling and mixing 0.1-11
Regular health checks help those vulnerable to respiratory sensitisation.
Above and left: New grainstores invariably have dust control equipment built in at the design stage.