Is Condensation Mould Growth Really That Bad For Your Health?

Richard Hughes,Residential Sales Manager


So many people within the social housing sector have asked me over the last twenty years or so to give my opinion on the true hazards presented by condensation mould growth. I meet people from across the social housing field that all have different opinions as to how seriously, or not condensation mould growth should be taken. Responses to condensation mould growth range from “open the windows and turn the heating up” at one end pf the spectrum to a fully proactive response, including some Housing Associations and Local Authorities who have actively programmed works that include fitting anti-condensation units within their problem estates to solve this issue once and for all.

When I am trying to answer this question I like to refer to evidence rather than hearsay or conjecture. There seem to be a lot of people talking about condensation in one way or another, and I have attended numerous seminars and presentations where each speaker has their own opinion on what is right, or wrong.

In order to try to cut a clear path through tangle of opinions firstly let’s look at current UK legislation. This places condensation mould growth firmly as a Category 1 hazard under the Homes Health and Safety’ rating system. This system was originally introduced to assist private landlords in identifying those hazards that were serious enough to warrant specific action. Furthermore, it allowed Environmental Health Officers the power to act in severe circumstances if they felt it was warranted. This alone would seem a fairly strong indicator of the serious nature of condensation mould growth within dwellings.

So what initially prompted condensation mould growth to be categorised in this way? One of the big drivers for this change in perception was The World Health Organisation (WHO) European Office Report. The WHO conducted considerable research into internal air quality and the issues associated with mould growth and condensation within the living environment. In 2009, the WHO even went so far as to bring all this scientific data together and issue The Guidelines for Indoor Air Quality Report based upon these numerous research studies carried out across Europe, Australasia, and America.

They recognised that problems of indoor air quality are an important risk factor for human health in low-income, middle and high-income countries. Indoor air quality also becomes even more important when populations spend a substantial proportion of time within buildings, particularly in day-care centres, retirement homes and other special environments; effecting groups that are particularly vulnerable due to their health, status, or age. The full report makes for pretty interesting reading. It is impossible to accurately summarise a document of this size, but it leaves the reader in no doubt that condensation mould growth is not something to be taken lightly.

One of the most effective methods of combating condensation mould growth is positive input ventilation (PIV). This technology, first invented by Nuaire in the 1970’s, has been used in thousands of homes across the UK, and is used across the globe to effectively combat condensation mould growth. The principals behind the system are even discussed in the WHO report, and the psychrometrics behind the unit’s success cannot lie. It’s interesting to listen to manufacturers talk about positive input ventilation, who, when asked about Psychrometrics in relation to the effectiveness of PIV, look blank-faced and change the subject. Without understanding this basic principle, PIV cannot be properly explained.

In relation to this technology the WHO’s  own report states that when outdoor air at a temperature of –8 °C and 100% relative humidity, which is usually very high in winter, is brought to an indoor temperature of 20 °C, its relative humidity decreases to 15%. Thus, cold but tempered outdoor air used in ventilation is effective in reducing indoor moisture levels.

The message is clear then. Condensation mould growth is a serious hazard to health and must be treated as such. PIV technology is a time-proven and scientifically-proven answer to this problem and can as such be used by social housing providers and landlords across the UK and beyond.

So when asked about the seriousness of condensation mould growth I always say yes it is serious, but luckily I know a man who can cure it!

Find out more about Nuaire’s condensation-curing PIV range – Drimaster for homes with lofts and Flatmaster for homes without lofts. Call us on 02920 850500 or email:

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