Humidifiers near you

The Health and Safety Executive lists humidifiers and air washers among the systems, alongside emergency showers, eye wash sprays, indoor ornamental fountains and aqueous tunnel washers, that can create a risk of legionella and are dealt with in Part 3 of its technical guidance on the control of legionella bacteria in other risk water systems. The reasoning is mechanical rather than alarmist: a water system becomes a foreseeable risk where the water can sit between roughly 20 and 45 degrees Celsius, where there is a means of creating and spreading breathable droplets, and where nutrients such as sludge, scale, organic matter or biofilm are present. A humidifier with standing water in a warm room meets all three.

The legal duties under that guidance sit on employers and those in control of premises, not on a householder running a unit in a bedroom. But the physics does not check whose house it is. The practical reading for a home is straightforward: do not let water stand in the tank between uses, do not top up a partly full tank rather than emptying it, clean the tank and any wick or disc at the interval the manufacturer states, and descale rather than let deposits build up, because scale is one of the nutrients HSE names.

The units that make the finest mist are the ones where droplet size matters most, which is an argument for evaporative designs in a bedroom and for taking the cleaning schedule of an ultrasonic unit seriously. A humidifier used in a room where someone is unwell, or where someone is immunosuppressed, deserves a stricter routine than a manufacturer's minimum.

Approved Document F sets its moisture criterion as the absence of visible mould on the inner surfaces of the external walls of a properly heated dwelling with typical moisture generation, and expects that criterion to be met whether or not anyone is at home. It converts that into two measurable forms: a surface water activity on the internal surfaces of external walls that should stay below 0.75 as a one-month moving average, 0.85 over a week and 0.95 over a day during the colder months, and, for new dwellings, the room relative humidity figures of 65, 75 and 85 per cent over the same moving average periods.

Those are ceilings, not targets, and they apply to a whole room rather than to the reading on a cheap hygrometer sitting next to the humidifier. What they tell a homeowner is that there is very little headroom in a British winter. A room at 45 per cent humidity is not obviously too dry, and raising it towards 60 to relieve a sore throat can put a cold external corner, a window reveal or the wall behind a wardrobe over the line where mould starts.

The document adds a caution people rarely hear: the moisture criteria needed to avoid house dust mite allergens are more complex and more demanding than those needed to avoid mould, and it does not give guidance on controlling them. If the household includes someone with a dust mite allergy, raising indoor humidity is working directly against that, and it is a question for a clinician rather than for an appliance manufacturer.

Most humidification in Britain is a plug-in appliance bought from a shop, and there is no trade to hire. Where a professional is involved it is usually for one of three reasons: fitting a unit into an existing ducted air system in one of the minority of homes that has one, investigating why a room feels dry when the rest of the house does not, or dealing with the damp and mould that have appeared after humidification. The variables in those cases are access to the plant, whether ductwork exists, how many rooms are affected and whether remedial work to a wall or ceiling follows.

LokalMatch is the introduction, not the tradesperson. Put the problem in once with your postcode — describe the room, the symptoms and what you have already tried — and heating, ventilation or damp specialists covering your area reply to you directly. Using LokalMatch costs homeowners nothing, while pros pay for the requests they receive. LokalMatch performs no work itself, sets no prices, and does not vet, rank or recommend any of the people who get in touch, so the judgement about who to trust remains yours.