Biological Hazards

There are a variety of biological hazards that may be present on a construction site and any of these could lead to disease if precautions are not taken to reduce the risks. Some of these diseases can be serious or fatal.

Not all sites will contain biological hazards. Sites where groundwork, refurbishment, or demolition work is taking place are more likely to be affected. Common hazards leading to potential for exposure to biological hazards that could cause disease include:

• bird droppings, for example in refurbishment or demolition sites - inhaling dust or water droplets containing contaminated bird droppings can lead to several diseases, including Psittacosis (a flu-like illness that can lead to pneumonia).
• discarded needles, for example from recreational drug use - needlestick injuries can lead to exposure to blood borne viruses including Hepatitis B&C and HIV.
• rat infestation and exposure to rat urine - rat urine or water contaminated with it can cause Leptospirosis / Weil's disease if it enters a cut or gets into the nose, mouth or eyes.
• contamination of the site with sewage or animal faeces - this can lead to infection with E.coli, a bacterium which can cause stomach problems or more serious ill health - sewage could also be contaminated with Hepatitis A.
• water systems that have not been drained or disinfected, containing stagnant water - these could contain bacteria which can cause Legionnaires' disease if spray / fine droplets contaminated with the bacteria are inhaled.

If any of these are present on your site, a risk assessment will be needed to determine the precautions to be followed when working on the site.

All sites must have adequate welfare and washing facilities, regardless of whether biological hazards are present. This is a requirement of the law. The washing facilities must include an adequately sized sink ie large enough to wash the hands, face and forearms. Hot and cold (or warm) preferably running water, soap (or other cleaning products) and towels (or other means of drying) must also be provided. In some circumstances, additional facilities may be needed. For example, when dealing with sewage, nail brushes and disposable paper towels should be provided in addition to the usual facilities. If heavy contamination is foreseeable, showers will also be appropriate.

A risk assessment will be required to determine the correct work methods and equipment to be used during the work but, in addition, where biological hazards are suspected, workers should practice good occupational hygiene including:

• washing hands and forearms before eating, drinking, smoking, using the telephone, taking medication, applying make-up, inserting contact lenses etc
• covering existing cuts and grazes with waterproof dressings and/or gloves before starting work. If cuts and grazes occur during work, wash immediately with soap and running water and apply a waterproof dressing
• taking rest breaks and meal breaks away from the main work area
• avoiding hand-mouth or hand-eye contact when in contaminated areas - for example, workers should not put pens/pencils in the mouth
• disposing of all contaminated waste safely

Areas for storage of clean and contaminated equipment must be kept apart and separate from eating facilities. Provision of suitable washing facilities and good hygiene measures, such as those described above, can be sufficient to control the risk of infection on some sites, depending on the hazards present.

Good washing facilities should be provided and good occupational hygiene measures should be followed, as described in the questions above, when dealing with bird droppings. Common activities, such as cleaning of windowsills, will not result in high exposures to infected material and are not high risk. For larger quantities, use of high pressure water should be avoided to minimise creation of droplets of water containing infected material, but wetting down the work area (using low pressure) will help to prevent inhalation of infected dust, reduce the risk of infection and will also prevent the spread of dust outside the work area. Containing the work area with plastic sheeting should also be considered. If required, following a risk assessment, for example when larger quantities of droppings are involved, a "P3" or "FFP3" mask should be used. These masks are designed to provide a good level of protection from particles in the air. A supplier of respiratory protective equipment (RPE) can help you choose the correct type of mask. If you need to use this kind of equipment you need to have a "face fit test" which is a test to ensure that the mask fits properly, before it is used. If the mask does not fit properly, it will not provide protection. Overalls should be worn when carrying out this work, and replaced when they are soiled.

Where there is a chance that needles might be  present, such as during demolition of derelict buildings or in areas where recreational drug use has been identified, a risk assessment should be carried out. This should include an assessment of the need for vaccination against hepatitis B for staff involved in removing the needles. You should consult an occupational health provider when doing this assessment.

Workers removing sharps, such as needles, from a contaminated area should be trained in how to carry out the work safely. A 'needle picker' should be used to remove them, rather than hands. Needles should be disposed of into a sharps box and the box should not be over-filled. Training should include the hazards associated with needlestick injuries, including the risk of infection with blood borne viruses, such as Hepatitis B & C and HIV, and the procedures to be followed during the work.

In the event of a needlestick injury, after appropriate first aid, the member of staff should consult their occupational health provider or the nearest A and E department, as soon as possible, to be assessed for PEP (post exposure prophylaxis) for HIV and post exposure immunisation for Hepatitis B, if not already vaccinated.

If you would like further information about biological hazards including:

• more information about working on sites contaminated with sewage;
• more information about Leptospirosis / rat urine;
• general information about biological safety and infections at work;

try these links:

• Working with sewage The Health hazards, hand card
• Working with Sewage The Health Hazards: A Guide For Employers
• HSE Infections at Work website

Trade associations and other industry bodies can also be a good source of information   about how to control exposure to biological hazards in your work.