Farming stirs up a lot of dust. We breathe it into our lungs when we till fields, make hay, harvest, grind and feed grains and when we work in livestock barns.
Livestock barn dust includes feed components, dried fecal material, hair and skin cells, feather particles, pollen, insect parts, moulds, fungi, viruses and bacteria.
And there are a lot of undesirables in that dirt.
Grain dust, for example, will carry particles of grain, soil and plant material, but it might also carry fungi, bacteria, residues of agricultural chemicals and the excreta of insects, rodents and birds. Spoiled grain is particularly contaminated with dust and bacteria.
Inhaled grain dust can affect the respiratory tract in several ways, none of which are any fun. It can also cause gastrointestinal issues, skin rashes and eye irritation. How our lungs are affected depends on the size of the dust particle, the number of particles we inhale and the source of the dust.
Size: it’s the little guys that are the most dangerous
Dust particles are measured in microns. One micron equals 0.001 mm. A dust particle of at least 10 microns can be seen floating in a sunbeam. That’s big enough to be caught inside your nose where you’ll either swallow it, or spit or sneeze it out. You might have a runny nose and watery eyes for a short while, but otherwise no ill effects.
On the other hand, dust particles between 4 microns and 10 microns, because of their smaller size, will slip through the respiratory system’s outermost defences and settle in the upper lungs and bronchial area where they might trigger asthma-like symptoms such as wheezing, laboured breathing and a cough.
But dust particles smaller than four microns can be even more sinister. They can make their way deep into the lungs where they can cause pneumonia-like symptoms including fever, chills, muscle pain, laboured breathing and wheezing.
Prolonged exposure to heavy grain dust or dust from any mouldy crop, straw, corn, silage, hay etc. can lead to serious respiratory diseases like Toxic Organic Dust Syndrome (TODS, also called grain fever) or Farmers Lung. Symptoms usually appear four to eight hours after exposure. Both diseases generate flu-like symptoms.
Numbers: The more the scarier
How many dust particles you inhale is also important. Canada’s Occupational Health and Safety Act regulations on biological and chemical agents states that the ceiling for grain dust is 400,000 particles per litre of air and 1,000,000 particles per litre for total dust.
Sounds like a pretty high ceiling, but in a dairy barn, for example, there might be about 10,000,000 (that’s right ten million)dust particles per litre if mouldy hay or grains are on the menu or mouldy straw is on the floor. Even in ideal conditions with good hay and straw, levels of 1,000,000 to 2,000,000 are commonly measured.
Feeding and grinding feed kicks up the most dust in the swine industry. An Ontario study found that during the normal working day, 27 per cent of operators were exposed to levels of dust which exceeded allowable levels.
For broiler, roaster, turkey and laying hen operations, the average number of dust particles is generally below 100,000 particles per litre of air, which is considered safe. However, levels spike during feeding time when all the birds are very active. The main health problems with poultry workers occur while moving or handling older birds; these symptoms could be attributed to exposure to the air-stew of dust, ammonia and endotoxins.
Sources and types of dust: not wanted dead or alive
Dust found inside livestock barns can be a mixture of organic and inorganic materials. In animal housing, 70 to 90 per cent of the dust is organic. Organic dust is “alive” and will react with the defense system of the respiratory system. Organic barn dust would include feed components, dried fecal material, hair and skin cells, feather particles, pollen, insect parts, moulds, fungi, viruses and bacteria. Inorganic dust is composed of numerous aerosols originating from such building sources as concrete, mineral or fibreglass insulation, or material, such as soil particles, drawn into the barn by the fresh air supply.
Health effects from farm type inhalants can be broken down into three categories. From not great to very bad they are:
- Some temporary damage to the respiratory system which rapidly disappears when the person is no longer exposed to dust.
- Insidious damage to the respiratory system such as bronchitis or occupational asthma after long term exposure to dust. Symptoms include coughing, shortness of breath or a reduction of pulmonary capacity. Most times when the workers are no longer exposed, the respiratory system may, but not always, recover entirely.
- Permanent lung damage. Some parts of the lung tissue are permanently affected reducing respiration capacity. Unfortunately, this process is irreversible.
A compilation of studies from Australia, Finland, Denmark, Sweden, Scotland, the USA and Canada indicate very high levels of occupational respiratory problems in farm workers. About 1 dairy producer in 5 has bronchitis problems directly related to the in-barn air quality.
So, what can we do to make it better?
The Canadian Centre for occupational health and Safety while cautioning that there is no simple method to prevent conditions that lead to conditions such as Farmer’s Lung advises that steps must be taken to deal with the problem at its root. Avoid crop spoilage and production of bacterial or mould spores that cause the allergic reaction. Workers must also take precautions to avoid breathing in spores from mouldy crops. The following measures are recommended:
- Wet hay, grain, or other crops can be dried at harvest. This is often an effective solution but it is seldom easy and usually expensive.
- If possible, hay with a high risk of spoilage should be stored in silage instead of bales.
- Buildings with large amounts of dusty material should be properly ventilated.
- Farm chores that involve handling hay or feed should be mechanized as much as possible to reduce exposure to moldy dust.
During cleaning of barns or stables, dust from mouldy crops should be wetted down before being swept to prevent it from becoming airborne.
Masks & respirators
A respirator is any device designed to provide protection against the inhalation of a potentially hazardous contaminant. Choose one that has been approved for the specific respiratory hazard involved in a style that fits properly and read and follow all manufacturer instructions for use and maintenance.
An approved toxic dust respirator is recommended when dealing with grain dust or fungal spores in livestock feed.
Alberta Agriculture and Forestry at their site at: http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex9742 offers this advice on fitting a respirator:
Wearing a respirator incorrectly is as dangerous as not wearing one at all. If the respirator does not provide a tight seal around the nose and mouth, the contaminant will leak through the seal. Choose a model approved by a recognized safety standards agency such as CSA. Check fit each time the respirator is used. More than one brand and size of a particular type of face piece are available. A fitting test can ensure the face piece fits properly. For best results, have the equipment fitted to the wearer by qualified personnel. Always follow the manufacturer's instructions for wearing the respirator. Check for a proper seal each time the respirator is worn. An easy way to check the seal is to conduct a positive or negative fit check:
For a positive check, cover the exhalation valve with the palm of the hand and exhale so that air builds up inside the respirator. If there is a leak, the wearer will feel it against the skin of his/her face.
For a negative fit check, cover the cartridge(s) with both hands and inhale. If there is no leakage, the mask will be drawn tightly to the wearer's face.
Most respirators will not seal properly if the wearer has a beard or moustache. Facial hair should either be shaved off, or the user should wear a powered air-purifying respirator if that type is appropriate for the respiratory hazard involved. Industries require that workers be clean-shaven if they have to wear respirators.
Nasty, nasty dust you must avoid
Though rare, hantavirus and anthrax are two potentially lethal diseases that you can get through your nose. To avoid hantavirus, be aware that there are mice on any farm. Control them religiously, and if you must enter a building where they could conceivably be hanging out, make sure to wear a well-fitting filter mask including a NIOSSH-approved 100 series filter such as N100, P100 and R100 (formerly called HEPA filters) or a respirator with P100 cartridges. An N95 mask may also be used. For more information, visit WorkSafeBC at www.worksafebc.com
Ventilate any enclosed areas for 30 minutes before cleaning. Wet down the area with household disinfectant before you start. Diluted bleach (1 part bleach to 10 parts water) can also be used.
Once you are wearing your mask, rubber gloves and goggles, and have done the prep work described above, follow these steps:
- Pour solution carefully onto debris to avoid disturbing any virus present – do not use a sprayer.
- Wipe up droppings, nesting materials and other debris with a paper towel and place in a plastic garbage bag. Avoid sweeping dry floors. Do not vacuum.
- Double bag the contents, seal the bags and bury, burn or place in the trash, according to local bylaws.
- Clean floors, carpets, clothing and bedding, and disinfect counter-tops, cabinets and drawers that have been in contact with mice.
- Wash rubber gloves with disinfectant or soap and water before removing them. Wash your hands with soap and water after removing gloves.
Inhalation anthrax develops when anthrax spores enter the lungs through the respiratory tract. It is most commonly contracted when workers breathe in airborne anthrax spores during processes such as tanning hides and processing wool. It is rare, but if you do either of these activities you should not work with the hides of diseased animals.
- Shirley Byers