Clean air - 1.4 Biological

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Occupational Asthmagens

Most people with asthma have irritable, swollen air passages, partly blocked with too much sticky mucus. This narrowing of the air passages leads to the symptoms of wheeze, breathlessness and cough.

Work and non-work factors can cause this narrowing or make it worse:

• dusts and fumes (both at work and at home, including cigarette smoke)
• exercise
• cold air.

People with asthma in the workplace may notice a number of symptoms including:

• either a dry cough or one that produces sputum. Often people whose asthma is caused or made worse by work will notice the cough predominantly at night
• shortness of breath or chest tightness
• wheezing.

All of these symptoms may improve when the person isn’t at work.

Asthma can result as an allergic reaction to a substance used in the work process such as TDI (toluene diisocyanate), or western red cedar.

The person has become ‘sensitised’ to the substance and this can occur after weeks, months or even years of being exposed without any ill effect. Sometimes the allergic reaction (and the symptoms) can develop some hours after the exposure. This can make the workplace factor difficult to identify.

Other people develop irritant asthma for the first time after a very heavy single exposure to an airway irritant in the workplace such as welding fume or an irritant gas such as sulphur dioxide.

Pre-existing asthma may also be made worse by factors in the workplace, such as dusts or fumes, and the symptoms tend to follow the exposure closely. The worker will often be very aware of the area of the worksite or of the substance which makes their problem worse.

Advice for people with asthma

Talk to your doctor or occupational health nurse if you suspect something at work is causing asthma or is making your asthma worse.

They will:

• ask you to note what substances or processes you are exposed to in your workplace
• ask you to note if your symptoms worsen during each shift or over the shift period
• ask you to note if there is any improvement away from work
• teach you how to measure and record a peak flow measurement. (This is a measurement of the amount of irritability of the air passages in your lungs.)

In New Zealand the substances or processes recognised as most likely to cause asthma problems are:

• working with chemicals such as isocyanates (TDI, MDI, two-pot paints and glues, foam manufacture, etc.) or epoxy resins.

Common industries include spray painting, boat building and working with wood dusts.

Problem dusts include:

• western red cedar
• some particle-boards (building and joinery industries)
• metal fumes or dusts (aluminium smelting, welding)
• dusts from organic materials such as flour (bakers) animals (veterinarians) and insects.

According to information found at:

www.health.state.ny.us

one out of every six asthmatics has asthma that is either caused, or made worse, by workplace exposures. There are over 350 occupational asthmagens. The US Association of Occupational and Environmental Clinics maintains a list at: www.aoecorg/aoeccode.htm

Selected occupational asthmagens by occupation*

Workers at risk	Agents
Animal handlers	Animal urine, dander
Bakers	Enzymes, flour/grain dust/mites
Carpenters	Acrylate, amines, diisocyanates, epoxy resins, wood dusts
Cleaners/Janitors	Cleaning materials, dusts, moulds
Day care providers	Cleaning materials, dusts, latex (natural), moulds
Electronics workers	Amines, colophony, metals, soldering flux
Farmers	Animal urine, grain dusts, mites, insects
Hairdressers	Henna, persulfate
Health care workers	Formaldehyde, glutaraldehyde, latex, methyldopa, penicillin
Laboratory workers	Animal urine, dander, feathers, enzymes, formaldehyde, glutaraldehyde, insects, latex
Machinists/Tool setters	Metal working fluids, oil mists
Office workers	Cleaning materials, dusts, moulds
Pharmaceutical workers	Cephalosporins, pancreatin, papain, pepsin, psyllium
Photographers	Complex amines
Plastics/Rubber workers	Anhydrides, diisocyanates
Sawmill workers	Wood dusts
Seafood processors	Crabs, prawns
Teachers	Cleaning materials, dusts, moulds
Textile workers	Dyes, gums
Welders	Welding fumes

Question: What do you do with this list?

Answer: You have a high index of suspicion in these workplaces.

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Bird droppings

Bird droppings, left behind by large numbers of roosting birds, are likely to be found by employees during:

• construction work
• maintenance work
• work in roof spaces
• demolition work.

The most serious risks are from organisms that grow in the droppings, feathers and nesting debris on ledges and in lofts. External parasites may also become a problem when infested birds leave their roosts and nests. The parasites they leave behind can invade buildings and bite or irritate people’s skin.

Some of the diseases that can be caused by the organisms in bird droppings are:

• bacterial - e-coli, salmonella, listeriosis, campylobacter, psittacosis
• fungal - histoplasmosis, cryptococcosis, candidiasis
• viral - meningitis, Newcastle disease
• parasitic/protozoal – toxoplasmosis, trichomoniasis.

The bacteria and parasites found in bird droppings can be

• breathed
• ingested by eating
• from eating with dirty hands.

Infection is most likely, however, when dust containing massive amounts of the bacteria or parasites is inhaled.

The risk of disease is greatly increased for people with weakened resistance which called result from things like:

• antibiotic therapy
• skin damage via injury or surgery
• chronic disease.

Precautions

Seal off windows, doors and ventilation inlets.

Dampen bird droppings with a gentle spray until wet enough to prevent dust becoming airborne. This may take several hours or more of repeated spraying to penetrate the droppings completely. (Strong jets of water may cause dust to become airborne and runoff may contaminate public areas.)

Wear a high efficiency (HEPA) dust respirator, disposable gloves and overalls. On completion of the job treat the disposable gloves and overalls and respirator filters as contaminated waste and add to the droppings for disposal.

Double bag the droppings and disposables in 3 mil plastic bags. Dispose in a landfill.

Non-disposable work clothing and respirators should be removed and sealed in a plastic bag. Disinfect in the bag before final cleaning and reuse. Shower after scrubbing boots.

Employers - select workers with high immune status. Medical assistance may be needed to obtain a medical history – with attention to current diseases such as cancer, prolonged oral steroid therapy, pulmonary disease, diabetes mellitus and other conditions. (Get the employee’s permission first.)

Avoid using chemicals. Chemical sterilisation of droppings before removal has NOT proven to be effective against all organisms (and may present another health hazard from chemical exposures).

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Legionnaires disease

Introduction

Legionnaires’ disease is a lung infection (a type of pneumonia) that can be either mild or severe enough to cause death. In its mild form, it is called ‘Pontiac fever’. The disease got its name in 1976 when an outbreak of pneumonia occurred in people at an American Legion Convention.

Legionnaires’ disease is caused by bacteria called Legionella. These bacteria are usually found in water and soils, depending on the species.

In New Zealand:

• Legionella pneumophila is the most common cause  - and is connected with hot water systems and cooling towers.
• Legionella longbeachae is the next most common and is found in soils, compost, and potting mixes.

Legionella can grow on wet surfaces of the cooling units that are part of some building air-conditioning systems and other industrial cooling equipment. It can also grow in pools of water, and its growth is more rapid the higher the temperature of the water. It will not grow in water over 60 degrees C.

In certain circumstances legionella can become airborne and be ejected out of a cooling tower or scrubber in water droplets. The airborne bacteria can be dispersed by the wind to affect members of the public outside a building, or be captured by poorly positioned air intakes of an air-conditioning system.

Some people are more at risk than others. Adults over the age of 50, smokers, people prone to lung disease and other people with low immunity are particularly vulnerable. Legionnaires’ disease is treated with antibiotics.

Legionnaires’ disease is not contagious and outbreaks are localised. In New Zealand, Legionnaires’ disease is a notifiable disease under the Health Act 1956. This means that a doctor is required to notify the medical officer of health at the Public Health Service if he/ she suspects a patient suffers from, or is diagnosed with, Legionnaires ’ disease.

The actions needed to prevent the growth of the bacteria are relatively simple. Comprehensive Codes of Practice (e.g. the New Zealand Guidelines for the Control of Legionellosis and the more recent New South Wales Code of Practice for the Control of Legionnaires’ Disease and Standards describe the design, operation and maintenance and monitoring of air-conditioning systems.

Preventing Legionnaires’ disease is more likely if you:

1. Choose a system that minimises the opportunity for the bacteria to grow:

• design or select plant elements that are easy to clean and minimise bacterial growth
• select processes that allow minimal opportunities for bacterial growth (such as using a hot water system with mixing valves instead of a tepid water storage system)
• design components to avoid sludge build up (legionella grow better in sludge)
• avoid dead-legs in pipework (so the bacteria cannot grow there)
• use drift eliminators (these are mechanical devices that prevent water droplets leaving a cooling tower)
• provide easy access for maintenance and cleaning
• replace inefficient equipment
• use a continuously operating disinfection process to kill any bacteria (see 3 below)
• position air intakes safely
• use an air-cooled system rather than a cooling tower (absence of water means Legionella can’t grow)
• use a closed-circuit system instead of an open circuit (this eliminates potential growth surfaces).

2. Keep water handling systems clean.

3. Treat the water with chemicals.  Specialist advice is needed on:

• the dosing equipment —its selection and operation
• bleed-off techniques (to avoid the accumulation of chemical residues)
• the choice of biocides (effectiveness vs ecotoxicity);
• water sampling and testing (regular quality control — in accordance with AS/NZS 3666.3: 2000 — Performance-based maintenance of cooling water systems) and
• routine cleaning.

4. Use the approach outlined in AS/NZS 3666.3 for monitoring water quality and interpreting the results. This standard also lists the actions that should be taken when these results indicate an increase of microbial growth in the water.

Practical actions for building and plant owners, operators & employers

These observations mean that there are some clear responsibilities for:

• owners and operators of buildings with mechanical ventilation systems
• operators of cooling plant or equipment
• some employers.

General responsibilities

All groups

1. ask for a condition report or specification on the safety and health of the air-conditioning system or cooling equipment.

2. Check the maintenance programme for the system/equipment.

3. Check water quality periodically. The final check for safety is to test for the presence of microbial growth in cooling water. This means that:

• building owners should ensure they get monthly reports on water quality and that they are able to interpret or have interpreted the results (see AS/NZS 3666.3 and the New Zealand Building Code). This will allow employers to demonstrate compliance to local authorities.
• employers should satisfy themselves that the airconditioning system remains safe — perhaps by seeking a copy of the monthly water quality report or requiring the building owner to report by exception.
• operators of cooling plant in industry should satisfy themselves that the cooling equipment remains safe. Since there are many similarities between air-conditioning units and cooling towers, monthly sampling and reporting of water quality is recommended. This type of plant could include cooling units in the following and settings:
  • food processing + storage
  • plastic moulding machinery
  • plants that operate emission control scrubbers to prevent the release of environmental air contaminants
  • cooling units for computer rooms or telephone exchanges
  • supermarket misting units.

Building owners

For responsibilities under the Building Act refer to: the Department of Building and Housing: www.dbh.govt.nz, in particular www.building.dbh.govt.nz/e/publish/bc-28.shtml and: www.building.dbh.govt.nz/e/uploads/

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Moulds and leaky buildings

What are moulds?

Moulds, along with mushrooms and yeasts, are fungi, which are simple, microscopic organisms. They are present everywhere, indoors and outdoors.

To grow they need a food source (any organic material such as leaves, wood, paper, or dirt), moisture and a place to grow. They don’t need light to grow.  When they reproduce they release countless tiny, lightweight spores, which travel through the air, and can be inhaled.

If indoor mould contamination is extensive, high airborne spore levels may exist. Exposure can also occur via contaminated foods, or by touching infected materials.

Adverse health effects

Everyone is exposed to some mould spores on a daily basis without noticeable harm without harm. But they can cause health problems when they are inhaled in large numbers. This may occur with very active mould growth in indoor working and living environments. Moulds can produce adverse health effects such as inflammation, allergy, or infection. Allergic reactions like ‘hay fever’ or allergic rhinitis and sinusitis are most common. In some people an allergic reaction to fungal spores may take the form of asthma.

Symptoms that exposed people report include:

• respiratory problems, such as wheezing and shortness of breath
• nasal and sinus congestion
• eye irritation (burning, watery or reddened eyes)
• dry, hacking cough
• nose or throat irritation
• skin rashes or irritation.

Although uncommon, infection from moulds can result in a fever. Other reported symptoms include headaches, memory problems, mood swings, nosebleeds, and body aches and pains; but their causes are not well understood.

People with pre-existing asthma are at greater risk, as even a relatively small number of spores may trigger an asthma attack. Similarly, those with weakened immune systems (such as people on chemotherapy or with HIV infection) will be more susceptible to infection, as may elderly people and infants.

Anyone suffering from the general symptoms described and who has been exposed to mouldy conditions should see their GP for a medical assessment.

A special danger

Certain types of moulds, such as Stachybotrys chartarum, can produce compounds that have other toxic properties called mycotoxins. These come from a greenish black mould that grows on material with a high cellulose content, such as fibreboard, the paper covering of gypsum wallboard, wallpaper and dust and wood when these become wet.

It requires very wet conditions for days or weeks in order to grow.

While Stachybotrys chartarum is growing, a wet slime layer covers its spores, preventing them from becoming airborne. Significant exposure to individuals can occur when the mould dies and dries up. Air currents or physical handling can then cause the spores to become airborne.

However, finding Stachybotrys chartarum in a building does not necessarily mean that occupants have been exposed to either allergens or toxins.

Just how much stachybotrys and other toxic moulds affect people is uncertain.

The key cause of Mould - dampness

Excessive indoor humidity resulting in water vapour condensation on walls from plumbing leaks, spills from showering or bathing, water leaking through foundations or roofs will promote mould growth.

Preventing mould growth is, in principle, a straightforward matter of keeping things dry.

Evidence of past or ongoing water damage (including warping of floors, or an earthy, musty odour) should trigger a thorough inspection of areas such as those underneath water-damaged surfaces or behind walls, floors or ceilings.

Significant sources of indoor moisture include:

• flooding leaky roofs or walls
• sprinkler spray hitting the house
• plumbing leaks
• overflow from sinks or sewers
• damp basement or crawl space
• steam from shower or cooking
• humidifiers
• wet clothes drying indoors or
• clothes dryers exhausting indoors.

Clean-up procedures

Dealing with mould is, in principle, simple through:

• Removing mouldy materials
• Cleaning and drying mouldy areas

1. Remove mouldy materials

Spores are more easily released when mouldy materials dry – so remove mouldy items and clean mouldy surfaces as soon as possible.

• discard porous materials from which it will be difficult to remove mould completely, e.g. paper, rags, wallboard, wood products, ceiling tiles, carpet, curtains, and upholstered furniture.
• contaminated carpet is often difficult to clean, especially when the backing and/or padding can become mouldy.
• solid materials (such as glass, plastic, and metal) can generally be kept after they are thoroughly cleaned.
• adequately bag and discard mouldy items - dispose with household rubbish.
• dry affected areas for 2-3 days.

2. Clean and dry the mouldy areas

• Use non-ammonia soap or detergent, or a commercial cleaner in hot water; scrub the entire affected area
• Use a stiff brush or cleaning pad on cement walls and uneven surfaces
• Rinse cleaned items with water and dry thoroughly. A wet/dry vacuum cleaner is helpful for removing water and cleaning.

Use of biocides:

Don’t use bleach or other biocodes, except in specific circumstances.

In most cases it is not possible to sterilize an area because of the presence of background mould spores – which settle on the area after it has been dealt with and remain viable.

Biocides may be deemed appropriate in some circumstances: for example if immune compromised people are present.

If they are used, adequate ventilation must be supplied.

Personal Precautions

Use respiratory protection when you are dealing with moulds. A respirator with particulate filter(s) (P1 minimum) is required for spores. With the prolonged substantial use of cleaning agents, a combined particulate and vapour respirator is preferable. If in doubt, consult a safety equipment supply company.

Protective clothing that is easily cleaned or discarded, and rubber or other suitable gloves should be worn

If you are concerned about the effects on your health, work for short time periods with rest in fresh air. Try cleaning a test area first. Small areas or light mould growths should not cause significant problems.

Gross contamination or heavy growths may be more of a problem for certain individuals.

Bleach fumes can irritate the eyes, nose, and throat, and damage clothing and shoes. Minimise exposure when using disinfectants with good ventilation and air it well afterwards. Wear gloves, mask and eye protection.

Never mix bleach with ammonia as toxic fumes may be produced.

Ozone air cleaners ARE NOT recommended. Ozone is a known lung irritant and is not effective in controlling airborne moulds and other microbial contamination. It may damage materials in the home, such as causing rubber items to become brittle.

Never use a gasoline or LPG-fuelled engine indoors for drying as this could produce dangerous levels of carbon monoxide.

Ensuring dry conditions will be the best way of preventing mould from growing.

Preventing mould growth

Inspect your building regularly for the indications and sources of indoor moisture and mould.

If a leak or flooding occurs, it is essential to act quickly:

• stop the source of leak/flooding
• remove excess water with mops or wet vacuum
• whenever possible, move wet items to a dry, well-ventilated area, or outside to expedite drying. Move rugs and pull up areas of wet carpet as soon as possible
• open furniture doors and move furniture away from walls to increase circulation
• run portable fans to increase air circulation. DO NOT use fans if mould has already started growing
• run dehumidifiers to lower humidity
• DO NOT turn up the heat or use heaters in confined areas, higher temperatures increase the rate of mould growth
• if water has soaked inside walls, it may be necessary to open wall cavities, remove baseboards, and/or pry open wall panelling.

Adapted from:

• California Department of Health Services. IAQ Info Sheet, July 2001.
• Mould Remediation in Schools and Commercial Buildings. USEPA. March 2001. On 13/11/08 at: http://www.epa.gov/mold/mold_remediation.html
• A brief guide to mould in the workplace. OSHA. 2003. On 13/11/08 at: http://www.osha.gov/dts/shib/shib101003.html

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Organic Dusts

Allergic respiratory responses

Organic dusts include vegetable and animal bio-aerosols such as:

• bark
• mouldy hay
• animal dander (dandruff!)
• mulch
• grain dust
• silage
• potting mix
• animal droppings
• urine spray
• aerosolised faeces.

Generally, human effects come from exposure to particles from grain, hay, pollen, fungi, fungal spores, mycotoxins*, bacteria and endotoxins*.

Dust from livestock also includes, for example, particles from skin, hair, feathers and excrement.

Exposure can cause lung diseases (some serious) from the allergic response.

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Mycotoxins - toxins produced by fungi.

Endotoxins - toxins from bacteria.

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The allergic response occurs when repeated exposures, over time, accumulate to produce dramatic lung responses on exposure to tiny amounts of substance.

The diseases are known by names like:

• organic dust toxic syndrome
• occupational asthma
• farmer’s lung
• Legionnaires disease

Problem assessment

Assessing the risk is difficult. Some people may develop the disease while others may not and different people may take differing lengths of time to become reactive to the airborne contaminants.

Any activity which could create airborne dusts, spores and liquid aerosols can lead to exposure, such as:

• disturbing mushroom compost
• producing, bagging, using potting mix
• removing animal droppings
• handling flapping chickens
• feeding-out mouldy hay
• seed dressing
• cleaning grain silos
• repairing leaky buildings.

Control measures

The primary aim is to reduce airborne contaminant levels.

• With waste material, dampening before disturbing but this would not be appropriate for products like seeds.
• In confined spaces (e.g. silos) avoiding entry using other work practices is the preferred option, however appropriate protocols for confined space entry must be developed and adhered to if entry required. In non confined indoor environments, specific ventilation may be required.
• Technical innovation which isolates the worker from the source, such as not needing to enter silos or seed cleaning plant

Personal protection - the last and least effective option.

Specific exposures

1. Urine/faeces spray – meat works and chicken processing.

• The problem: Airborne droplets containing urine and faeces (meat and chicken processing respectively) may transmit zoonotic diseases such as leptospirosis and campylobacter (respectively).
• Assessing the risk: Difficult – can only be done by measuring the incidence of the disease in the employees in the area.
• Control: Shielding over processes to prevent sprays of droplets, wearing face shields, frequent hand washing, work practices to prevent the generation of sprays and splashes, covering cuts.

2. Chicken farms

The problem: People working in chicken sheds may, over time, develop a variety of respiratory diseases including asthma and extrinsic allergic alveolitis (farmer’s lung). These diseases develop due to cumulative reactions to proteins and other substances in the litter that become airborne. Fungi are often the cause and another well-known known cause is mouldy hay.

Assessing the risk: Difficult. Allergic reactions occur only in a minority of individuals, and such clinical sensitisation may not occur for months or years after exposure began. (There are few factors known to influence susceptibility to allergic alveolitis.)

Control:

• limiting the time of exposure
• avoiding exposure
• selection of appropriate PPE. The use of battery-powered supplied-air helmets.
• avoid prolonged dampness – which aids fungal growth.

3. Grain dusts

Grain production has been associated with both inflammatory and allergic conditions of the upper and lower airways. This is due to the toxicity of grain dusts and/or their contamination by fungal spores or bacterial endotoxins. Control is by ventilation and confined space entry protocols.

4. Feed additives

Vitamins and enzymes are added to animal feeds to enhance the feed’s properties. Exposure to enzymes used in animal feeds has been linked with occupational sensitisation.

5. Mushroom farming

Characteristic symptoms include fever, dry cough, dyspnea*, chills, malaise, myalgia and tachypnea. These are caused by immunological reactions to inhaled antigens like Micropoly spora faeni and Thermo-actinomyces vulgaris.

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Dyspnea is difficulty breathing.

Myalgia is muscle pain.

Tachypnea is rapid breathing.

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6. Potting mix

The problem: Hazard from dust due to its bacterial contamination with Legionella bacteria. Symptoms include fever, rigors, sweating, vomiting, cough, chest discomfort, respiratory distress, and pneumonia.

Assessing the risk: Tests of New Zealand potting mixes have revealed a significant percentage positive for Legionella species. Prolonged storage, particularly at higher temperatures, can increase Legionella concentrations. Poor work practices also increase the risk.

Control:

• open bags slowly - opening away from face
• wet soils to reduce dust levels
• avoid working in poorly ventilated areas (e.g. enclosed greenhouses)
• use a dust mask
• store bags in a cool area.

Medical practitioners and Public Health Units can provide assistance in diagnosis and management.

7. Seed dressing

Seed dressings are fungicides applied to seeds before planting to protect the seeds against fungi or pests. Preparation and application can result in exposure. Appropriate controls i.e. extraction ventilation, PPE, administrative controls are required.

8. Piggeries and chicken farms – exposure to ammonia from urine.

The problem: Ammonia from urine may result in symptoms of acute poisoning – weepy eyes, coughing and other signs of irritated airways. Animal confinement can produce hydrogen sulphide as well.

Assessing the risk: Self-indicating. The extent of these symptoms and their severity will reflect the degree of exposure

Control: General air ventilation. Piggeries should have at least 12 air changes per hour. This is a theoretical concept that assumes that all the air in the space changes and that there are no ‘dead spots’. Frequent cleaning of the pens.

References:

www.cdc.gov/nasd

www.av.se/dokument/inenglish/legislations/eng9411.pdf [pdf file]

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