UV-C acts only where the radiation physically reaches. That is both its strength and its main limitation.
UV-C is the short-wavelength band of ultraviolet radiation. This radiation is absorbed by the genetic material of micro-organisms and damages its structure so that the cell loses the ability to reproduce. It is not a chemical reaction with the surface but a physical effect of light.
Two main properties follow from that. The advantage: nothing is left behind. No chemicals, no residue, no smell. Once the lamp is switched off there is nothing in the room that was not there before, and surfaces do not need rinsing. The drawback: the effect lasts only as long as the lamp is on, and extends only as far as the light reaches.
UV-C works only where the radiation physically reaches — in a straight line of sight. Light does not bend round corners and does not pass through opaque material. In practice that means:
That is why UV-C is rarely the right choice as the only method for disinfecting a room. The comparison is simple: ozone or fog reaches everywhere the air reaches; UV-C reaches only where the light reaches. In a room with furniture, light reaches far fewer places than it seems.
UV-C treats what the lamp can "see". Everything else stays untreated.
Three factors decide whether UV-C treatment achieves anything at all, and all three are measurable things rather than opinions.
If UV-C is offered as a complete disinfection solution for a property, two questions are worth asking: how the places the light does not reach will be treated, and how long the lamp has to run at the given distance. Often there are no answers.
The most worthwhile use in practice is exactly this: treating air in a closed recirculation unit. There all three factors above are controlled — the distance is short and fixed, the exposure time is set by the airflow rate, and there are no shadows at all. Units like this can run with people in the room, because the radiation does not leave the housing.
A lot of mistaken ideas have built up around this method, and some of them cost money.
One more practical warning: lamp output falls over time, even while the lamp is still lit and looks normal. An old lamp gives a weaker effect for the same exposure time, and there is no way to judge that by eye.
UV-C radiation is harmful to the eyes and skin — it acts on human cells the same way it acts on the cells of micro-organisms. So during treatment with an open lamp no people or animals may be in the room, and you must never look directly at the lamp. Units with a protective housing that treat air in recirculation are the exception — they can run with people present, because the radiation does not leave the housing.
Two more practical notes. First: UV-C can gradually damage some materials — plastics, paint and textiles age faster under prolonged, repeated exposure. Second: after treatment the space is usable immediately, as soon as the lamp is switched off. This method needs no airing, and that is one of its real advantages.
We usually use UV-C as part of a combined treatment, so the price is set by the overall scope of the work. We prepare an exact quote after the inspection. All prices →
It can be useful for specific tasks, for example treating air in a recirculation unit with a protective housing. As a solution for disinfecting a room it is limited, because it works only in direct line of sight.
In most spaces, no. It is a good additional method for exposed, clean surfaces and for air, but it does not reach shaded zones, textiles or gaps.
Yes. Once the lamp is switched off there is no more radiation, no residue is left and no airing is needed. That is this method's advantage.
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