Is there a smell after disinfection

By method

None of these smells resembles what people often imagine — the household smell of bleach. Professional products are chosen with the fact that somebody has to live in the room afterwards in mind. If you are sensitive to smells, say so in your enquiry: it affects the choice of method, and the answer is often ozone treatment, which leaves neither residue nor smell at all.

Why a smell appears at all

Each method produces a smell for a different reason, and that also determines how quickly it goes.

There is also an opposite effect worth knowing about: in the first hours after treatment people notice smells more sharply, because their sense of smell has been “reset” by time spent outside. That does not mean the smell is stronger — it means you have just come in from outdoors.

A smell after treatment should weaken every day. If it gets stronger, it is no longer about the treatment.

How long it lasts

In most cases the smell is gone once the property has been aired properly. It can last longer if:

• there are a lot of textiles and soft furnishings in the room to take up smells;
• the airing was insufficient or the windows were only left on the latch;
• air exchange in the room is poor — the extract does not draw, there is no incoming air;
• the treatment was intensive because the problem was large;
• the weather outside is warm and damp, so evaporation is slower;
• the room was shut up for several days after treatment and nobody went in.

That last point is commoner than you would think — especially in rented flats and newly bought properties, where nobody goes in until the following week. In a closed room the smell goes nowhere, because it has nowhere to go. The answer is not a repeat treatment but one thorough airing.

Two different smells that get confused

This is the most important distinction on the page. If there is a smell in the room after treatment, first work out which of the two it is — because what you do about it is completely different.

If what came back is the original smell, it is not a treatment smell and it is not a failure of the product. It means the source has not been fully eliminated: something was left in a material, in a duct, under a floor covering or on the neighbours' side. We have written more about tracing sources in the section on odour removal.

If the smell does not go

Check the simple things first — in most cases the answer is here:

• Whether the room has been aired properly — windows wide open, not on the latch, with a through draught.
• Whether the extract ventilation is working. Test it with a sheet of paper, keeping a window slightly open.
• Whether wardrobes, drawers and doors were open during the airing.
• Whether the traps have water in them — in a rarely used shower or floor drain the trap dries out and lets sewer smell through, which has nothing to do with the treatment.
• Whether the smell is from a new source: the bin, the washing machine seal, the fridge.

If after that the smell is still strong or still noticeable several days later, get in touch. That is not normal, and we will look at it. In most such cases it turns out that one specific point was left untreated — a ventilation duct, the space behind fitted furniture, or a material that should have been removed.

How to describe it so that we can help

A smell is the hardest kind of enquiry, because it cannot be photographed. The description is the only thing to work with, and a few details change everything.

A worked example

A client reported a smell that came back on the third day after ozone treatment. The description pinned down two things: it was stronger in the kitchen by the sink, and only in the evenings. It was not a treatment residue — it was the trap on the rarely used second sink bowl, which had dried out and, in the evening when pressure in the stairwell changed, let sewer smell through. The solution was a glass of water, not a second treatment.

When the answer is less welcome

There are also cases where the smell has soaked into a material that is not worth treating again, and the right solution is to replace it. An old mattress, a damp acoustic underlay beneath laminate flooring, or a layer of plaster that stayed wet for a long time are typical examples. In those cases we say so openly — a treatment that hides something for a month is not a service.