A range of ailments can be attributed to these organisms such as respiratory allergies, sore throats, tuberculosis, legionnaire's disease and frequent common colds and the flu.

Those people who are at most risk from such airborne pollutants are the very young and the old, consequently it is these age groups that tend to benefit most from UV air purifiers.

UV light has an even shorter wavelength than pure violet light, being just off the visible spectrum UV it thus invisible to humans.

Three categories of UV exist:

380-315nm, known as UVA this was used in so-called 'backlights' during the 1970's

315-280nm, this is termed UVB

less than 280nm, this is called UVC and happens to be most effective at killing microorganisms

All three levels of UV have the capacity to damage people's eyes and promote skin cancer. UV has been seen to be very effective at killing microorganisms. This is achieved by the UV wavelength in use damaging the DNA of the organism, the energy contained breaking apart and misplacing the nucleotide bonds, as such lowering the chances of the organism's self repair or reproduction. Very small organisms like these have short lifespans and so purification results occur fast.

Two particular UV wavelengths have proved best at being absorbed by air bound microorganisms, and therefore killing them, 185nm and 265nm. Hence all good UV air purifiers need to utilize wavelengths similar to these.

To ensure that your UV air purifier works to its maximum pathogen killing capacity the date when a new bulb is introduced needs to be recorded. UVC does eventually stop being emitted, whilst the bulb its self continues for some time further and so can appear to still be functioning to the first-time user. The best place to record the date is typically using permanent marker on the underside of the purifier. Based on the manufacturer's recommendations you are then able to calculate the life of the bulbs and so know when replacements are required.

Air filtering systems should always be employed ahead of the UV lamps in the purifier to stop particles in the air (e.g. dust and pollen) landing on the lamps and shielding the emitted rays. The majority of UV air purification therefore works in tandem with HEPA and/ or activated carbon to begin with, UV being the final purification stage.