Indoor air: the danger of quick-fix solutions to damp and mould

But her condition kept getting worse. Her eyes swelled up. The rashes blistered and the blisters wept. Even though her parents tried to stop her, she would scratch at her raw skin, drawing blood and scraping her skin off. Her downy baby hair fell out in chunks, leaving bald patches.

“She had to be restrained 24/7, and no matter how I held her, she would rub either the front of her face or the back of her head against me for relief,” Ms King says.

They kept going to the GP, to no avail. The creams seemed to have no effect, and Becky’s condition got worse and worse. In November, she went into anaphylactic shock and was rushed to hospital, where doctors narrowly saved her life. 

After her condition stabilised, the hospital ran blood tests and these produced a curious result: Becky had been suffering a sensitisation reaction to alternaria mould.

It was a light-switch moment for Mr and Ms King. On return to the property, Mr King inspected the PIV unit and found mould inside the air filter. He told the landlord and turned it off, afraid that the unit had been spreading mould-contaminated air around the house, which his daughter had been breathing in.

The council carried out a house survey, which identified many issues: insulation inside the cavity walls had become sodden, and damp had started to spread through the walls. Wood rot in the roof, along with waterlogged soffits and damaged guttering, were also contributing.

“A PIV cannot compensate for active leaks, structural dampness, saturated materials, insufficient insulation or existing contamination”

Work was carried out to fix these issues, but Becky’s symptoms were still serious: the rashes left her skin shining and raw. Her breathing was effortful. “I was balling my eyes out every day,” says Ms King. “There were times I thought she would die and there was nothing anyone could do.”

By now, the older children were also suffering from breathing and skin problems, although not as seriously as their baby sister was. In desperation, the family moved out, paying rent on a second home they found privately. 

At this point, something apparently miraculous happened. Almost as soon as the family moved into the new property, Becky’s skin began to heal, her breathing stabilised and her hair grew back. Mr and Ms King show me photos of her transformation from a sobbing, red raw, bald baby into a healthy-looking one-year-old within a matter of weeks. 

The council landlord sent workers over to ‘dry fog’ the house, which involves pumping a mist-based pesticide (peracetic acid) through the property, claiming that it would eradicate the mould.

The family was told the house was safe to return to, so after three months, they moved back to their former home, hoping that the fogging had done its job. 

The health conditions came back almost immediately. Becky’s skin deteriorated quickly, and so did the health of the other children, who got nosebleeds immediately on re-entering the property and went on to develop other symptoms, such as mouth ulcers. Further blood tests revealed a sensitisation to another mould in Becky’s blood.

The family were desperate. They thought their baby daughter was going to die. 

Thanks to several reports and assessments of their home, the King family now have a clear understanding of what was happening to their home and their children.

Inside their attic, where the PIV system was located, the roof was suffering from areas of wet rot. This rot became so severe that the roof would actually be deemed in need of full replacement in 2023, but when the PIV was fitted in 2022, it somehow wasn’t spotted. Instead of circulating clean air, the PIV unit was pulling in mould spores, small enough to pass through its filter, which then circulated throughout the air in the rest of the property.

An air sample revealed high levels of airborne fungal particles. Swabbing on the property in May 2023 revealed the presence of aspergillus spores, which can cause severe health issues. The proportion of this type of spore actually rose after the property was fogged, shown by air samples taken before and after. 

“The installation of the PIV by the landlord into a contaminated and decaying roof space/loft was a major mistake,” said a report from an expert indoor environmental hygienist, acting for the tenants. “This PIV… was effectively pumping loft contamination into the occupied spaces of the home.”

PIVs are fitted with filters that are supposed to keep dangerous particles out. But the filter on this PIV allowed some very small particles through, meaning dangerous mould spores were able to pass through. An independent report from property consultancy Savills, commissioned by the council, agreed with the conclusion.

“My opinion is that a PIV unit was not suitable for application in this instance, given its location within a contaminated environment and use of a filter which allowed potential for mould spores to pass through the filter,” it said. 

The tenants’ independent report added that the attempt at ‘fogging’ would have made the situation worse, as it would have “increased contamination within the property”, by forcing mouldy air out of the cavity in which it was mostly contained. 

The family had been breathing in these spores for months. The fungi was entering their bloodstreams, causing illnesses.

What happened to the Kings is not unique. After years of rising awareness of the risks of damp and mould, and following the introduction of Awaab’s Law in October, social landlords are reaching for methods to rid their properties of mould. But there is a risk that these solutions can make problems worse – especially if they fail to consider the pivotal question of indoor air quality.

“If the air can leave the property, it can push the stuff you don’t want out. But if the air can’t leave, it’s doing nothing – you’re just creating mould soup”

PIVs are typically fixed in a loft space, with a hole cut in the ceiling beneath, and a vent fitted. The unit then draws in the air from the loft, and pushes it around the home. This is supposed to stop moisture settling on walls and create a positive pressure differential to force indoor air out through the home’s ventilation system. 

While this might work in a home with a perfectly clean loft space and ventilation to take the air elsewhere, in a poorly ventilated home with contamination in the loft, it will circulate poor-quality air straight into the lungs of the residents.

“Obviously the loft is not a controlled space; it’s quite often a dirty, contaminated space where pollutants can be introduced, either through a leak or a rodent moving in, or the breakdown of insulation,” explains Lisa Malyon, founder of the campaigns Indoor Air Aware and Mums Versus Mould, and the new UK Centre for Mould Safety. “Then, the danger is that a PIV unit sucks all of those things into the family’s home.”

Dr Suhail Ahmed, a microbiologist who works for the remediation firm Action Dry, says: “A PIV is not a standalone mould remediation solution. A PIV cannot compensate for active leaks, structural dampness, saturated materials, insufficient insulation or existing contamination. It also requires clean loft air, correct filtration and proper commissioning and filter maintenance – otherwise it can introduce dust or fungal particulates into the living space.”

Manufacturers advertise the systems as providing “fresh, filtered air” and say tenants will no longer need to open their windows to prevent condensation. But the reality is more complex. In fact, if the property is not properly ventilated, and if the roof space is contaminated, they are simply circulating that air around the property. 

“PIVs are seen as a Hail Mary solution,” says one asset management expert, who asked not to be named. “There is a good margin on them for the contractors, so they like recommending them. And some housing associations like the idea that they can plug it in and forget about it. But it all comes down to the quality of the install and the quality of the ventilation. If the air can leave the property, it can push the stuff you don’t want out. But if the air can’t leave, it’s doing nothing – you’re just creating mould soup.”

Kelly Butler, director of external affairs at the British Electrotechnical and Allied Manufacturers’ Association (BEAMA) – which includes companies that make and sell PIV units as its members – says the key question is whether the product is properly installed, adding that the same can be said of all ventilation systems and other building services.

“This is a question of proper regulatory enforcement. It’s not the biggest-selling solution on the market, but it has been really popular in recent years – particularly in social housing. It does work, but we do need to make sure that the standards are properly followed,” he says.

“The market uses a two-step distribution model: PIVs are sold through wholesalers and specifiers and installed by contractors, which means manufacturers don’t always know where their products are being used.”

EnviroVent, the company that made the PIV used in the Kings’ house, declined to comment, referring Inside Housing to the statement from Mr Butler.

Data gathered by Inside Housing from a group of larger stock-owning councils show that the products are, indeed, widely used in the sector. Nottingham Council, for example, has installed 309 devices, and plans to install a total of 800 by March. Gateshead has installed 1,225 devices. Both councils say, in statements, that PIVs are not used as blanket solutions, but are part of a wider damp and mould strategy.

The potential reach for a quick fix with PIVs is part of a wider risk with Awaab’s Law. Given the new timelines in which issues need to be addressed, and the potential for legal claims if they are not, there is a risk that landlords will reach for apparent solutions that might actually make the situation worse. 

“The market is massively under-regulated, and we’re seeing so many companies offering their lotions and potions, telling social landlords that they can remove mould in a single day or a few hours,” says Nathan Wood, a ventilation specialist and managing director of contractor Farmwood. “Too many people have been on a two-day course and are now out in the market claiming to be experts.”

No quick fixes

The reality is that there aren’t quick fixes for damp and mould, Dr Ahmed says. Time-consuming as it may be, mould and water-damaged materials need to be removed, and the conditions that caused the mould to form must be eliminated.

“The most effective way to deal with mould is to remove the visible and hidden growth safely, control the moisture source that allowed it to develop, and improve heating and ventilation so conditions don’t allow it to return,” he says.

Mr Wood adds: “The only true way to guarantee mould remediation is actually to cut it out and remove it. Don’t stain it, don’t seal it, don’t fog it or bleach it. All you’re going to do is remove the visual signs. But 80% of mould is invisible, and what’s dangerous to health is the particles in the air.”

Fogging – where a mist of chemicals is pumped through the property in a bid to kill the mould spores – also comes with risk.

“The fogging process simply breaks the mould spores down into smaller pieces, which are more easily inhaled,” Ms Malyon says. “I know of people who have been left unable to function upon returning to their property after it’s been fogged – their properties are uninhabitable and they lose everything.”

Industry figures say that the key standard for home retrofit work, PAS 2035, requires “complete ventilation”. But in reality, this is often overlooked, with homes rendered effectively airtight by new insulation systems.

“Modern buildings can’t breathe as they used to. People planning remediation work are simply not addressing the ventilation strategy,” Mr Wood says.

The health hazard related to damp and mould is obvious: there was the death of Awaab Ishak, as well as research including a recent report from the Centre for Ageing Better, which showed that in 42% of homes that have condensation, damp or mould, there is at least one person with asthma and/or a weakened immune system. This is almost double the proportion for households that have never had such issues. These health impacts relate to what is breathed in, not what is visible on the walls.

As the sector grapples with its new responsibilities on damp and mould, it needs to remember that quick solutions may not always work. “Unregulated solutions are doing so much harm,” Ms Malyon says. “I know because people are coming to our service to ask for help.”

“The market is massively under-regulated, and we’re seeing so many companies offering their lotions and potions, telling social landlords that they can remove mould in a single day or a few hours”

So what became of the Kings and their daughter Becky? After a prolonged struggle with the council, they were finally decanted from the property on health grounds and offered alternative accommodation. Most of their possessions from the former property will likely have to be destroyed, as they are contaminated with mould spores. 

All but one of the family’s children have lingering health concerns, as do the parents. Four of the children have an asthma diagnosis, which they did not have before the arrival of the PIV. 

By the time we have finished talking, the table in front of them is scattered with wince-inducing photos of baby Becky, which they took for evidence when her condition was getting worse. With some trepidation, I ask how she is now. 

Mr King gets up. “Becky!” he calls. “Come in here for a minute.”

In walks a healthy, happy-looking three-year-old girl, her hair down to her shoulders and no signs of rashes or scars. “Say hello,” Mr King prompts.

Becky manages a small smile, but is a bit too shy to say hello to the strange journalist sitting in her parents’ kitchen. Mr King smiles and she trots back off to watch television with her brother and sister while we finish up. 

While her health has improved drastically from those terrifying months, she is still not completely OK, and probably never will be. Her diet is severely restricted because of her high histamine response, and catching a common bug can mean a trip to A&E and a stint on a ventilator. The whole family have to be incredibly careful about germs as a result.

But given that at one stage it looked like she might not survive at all, it must be a huge relief to see her healthier than before. Mr King’s face, stoic and matter-of-fact throughout the interview, clenches for a moment, but he keeps his composure. “We just want to make sure no other family goes through it,” he says.

*Names have been changed