Common mould is health hazard

PUBLISHED : Friday, 21 May, 2010, 12:00am
UPDATED : Friday, 21 May, 2010, 12:00am

Indoor mould is hazardous to your health. In extremely rare cases, over-exposure to a certain type of mould may lead to death by asphyxiation, according medical science.

Because of Hong Kong's high humidity during spring and summer, mould tends to grow in homes that are poorly ventilated and damp.

'The most common [health problems] caused by mould are coughing, chronic sinus problems, runny nose, headaches and fatigue,' says Phillip Fry, a toxic-mould consultant.

He also says there are thousands of mould species and each one is unhealthy to humans if it is present at elevated levels indoors.

The two most common species of mould that are unhealthy to humans are aspergillus and penicillium - and the toxic mould stachybotrys can cause severe brain damage.

Although illness caused by mould spores is not something new, Fry says awareness of the problem has been increasing in Hong Kong over the past few years.

There has also been media attention to the health problems associated with mould.

One can detect indoor mould, apart from visual sightings, by the odour it releases.

If the air is damp and there is a musty and stale smell, all walls, ceilings and furniture should be inspected to see if there is any mould growing.

Even air conditioners are vulnerable to mould. Fry says air conditioners need to be cleaned every three months.

The best way to remove mould is to scrub it off, and the most effective way to get rid of it is to dilute boric acid powder with water.

'Mix a quarter of the acid powder with two gallons of warm water and use it to scrub the mould off the infected area. No matter what type of mould it is, this process is [effective],' Fry says. There is also Fry's 25 steps to remove mould in his website (

He stresses that mould spreads fast and must be eliminated quickly.

If the mould has spread over a large area, Fry recommends hiring a professional to remove it.

However, people should be wary of the professionals they hire, as many tend to use ineffective mould-removing methods. 'Often, mould removal is done by maintenance companies that lack training in how to safely and effectively remove it. For example, most try to remove it with bleach, which is not effective for killing mould,' Fry says.

According to Fry's website, one reason why chlorine bleach is not effective is that it is too dilute to permanently kill mould.

Bleach also does not penetrate porous materials, such as wood, and it only remains on the surface.

There are, however, simple and effective preventive measures to keep mould out.

'Use a dehumidifier to keep indoor humidity to less than 70 per cent and preferably as low as 40 per cent to discourage mould growth,' Fry says. Also, regular inspection for water leakage is also an effective preventive measure.

There are also special wall paints, such as ICI Dulux Paint, that prevent mould from growing.