The hidden dangers of mould – part one

Health Check
How healthy is your building? Mould is usually an indicator of hidden damp issues caused by leaks, poor ventilation, the spore released by mould can cause health issues to employees/staff.
Moulds release spores that, like dust allergens, can cause allergic reactions in people. Spores are microscopic particles released by moulds into the atmosphere in their thousands. Spores come into contact with skin and nasal and bronchial membranes, causing symptoms such as rhinitis, itchy eyes, eczema and, most importantly, asthma. Several conditions, such as Farmer’s lung and Sauna-taker’s lung, are caused by mould allergy.

Mould can easily grow in areas like this

Mould growing on a wall

Causes of damp and mould
Mould growth is caused by excess moisture due to condensation, leaking pipes, rising damp in basements or ground floors or rain seeping in because of damage to roofs or around window frames are major causes of damp.
The following are the optimum conditions for mould to thrive:
• Moisture (e.g. water leaks, humidity, cooking)
• Oxygen in the air
• Mould spores already present
• A food source for the mould spores (e.g. rotting food, paper, wood, cotton)
• Darkness (mould can’t grow under ultraviolet light)
• Warmth (mould can’t grow in freezing temperatures)
• Enough time (most moulds can begin to grow in 24-48 hours if the conditions are right)

Recommendations for the prevention of mould
The following are recommendations to prevent condensation and the optimum conditions for the growth of mould in a building:
• When cooking, use extractor fans and cooker hoods which are vented outside to manage the amount of condensation produced from steam.
• Good insulation and adequate heating will keep a building warm.
• Regular ventilation of rooms will prevent stale, moist air which can lead mould growth.
• Planned preventative maintenance, such as repairing any leaks, will help contain the spread of mould.
• Thoroughly cleaning kitchens, bathrooms and utility rooms will help prevent the conditions for mould growth.
• Thorough cleaning of walls behind kitchen units and cupboards will help prevent the conditions for mould growth.
• Thorough cleaning of food preparation areas and refrigerators, particularly refrigerator seals, is required. Do not let food decay.
• Leave wardrobe doors ajar to ventilate clothes as mould can begin here.
• Check tumble dryers are vented outside during use, or use a condenser-dryer to ensure good ventilation.
• Get rid of old foam pillows and mattresses where mould spores can begin.
• Mould has a tendency to start under wallpaper that is beginning to peel. Tackle any areas of dampness on walls and remove wallpaper. It may be better to paint the walls.
• Remove piles of old papers/stored documents where mould can begin and then spread to other areas.
• Keep indoor plants to a minimum and change the soil regularly as mould grows on the surface of the soil.
• Do not use humidifiers as humidity will encourage mould formation.

Adequate ventilation
Adequate ventilation is necessary but containment of spores is essential. Open the windows but keep doors closed to prevent spores spreading to other areas of the building. Put up safety signage and ensure no person is allowed to enter the room whilst cleaning is being completed.

Prepare the environment
Prepare the environment and remove any items of materials such as soft furnishings, clothes etc that are mouldy. Dispose of any items that are not easy to clean.

Cleaning Technique
• Use a wash basin containing water and a 1-to-8 bleach/water solution. In addition there are chemical solution products on the market for to help with cleaning mildew and mould. Ensure that the instructions are followed carefully.
• Contain the mould with the wet cloth and carefully wipe the mould off the wall. Be careful not to brush it, as this can release mould spores. The bleach in the cleaning mixture kills the mould.
• If the mould doesn’t disappear after light scrubbing, reapply the cleaning mix for a couple of minutes. Then lightly scrub again.
• When the cleaning is finished, use a dry cloth to remove the moisture from the wall. Dispose of all cloths used on the cleaning of the mould.
• Don’t mix ammonia or any detergent containing ammonia with bleach. The combination forms a poisonous gas.
• As a further precaution all the surfaces in the room should be thoroughly cleaned by wet wiping to remove any spores.

For more advice on how to tackle mould contact Mary at Principal Hygiene on 01772 817600 or email her at