The use of UV-C lamps and their effects

Prof. Dr. Sermin Onaygil


The use of UV-C radiating lamps is nowadays a hot topic as a method to eradicate Covid-19 viruses. In fact, UV-C lamps have been utilized in water treatment and air disinfection. With its known adverse effects on skin and eyes in case of direct contact, lamps need to be used in combination with well-designed and controllable systems. It is observed that current applications are conducted unconsciously, not only in our country but also across the world. The important matters and deficiencies, as summarized below, should be taken into consideration in the use of UV-C radiation sources. 

·       Threshold limit values are available for 254 nm based upon scientific researches with no risks on health. Certain values are also released for 270 nm and 222 nm. The sources must generate radiations at wavelengths of known risk threshold limits. Typically, low-pressure mercury vapor lamps of 254 nm are used as the calibration source of instrument in UVR measurements. Spectral mismatch errors between 10% and 50% may occur if measured wavelength of radiation is different than that of calibration source. Therefore, it is not suggested to use LED’s for germicide purposes and their antiviral effects are revealed to be poor.

·       In case of use of UV-C sources with different wavelengths, non-risky threshold limit values (TLV) must be specified.

·       The densities and operating times of UV-C radiations must be controlled with built-in sensors and automation systems.

·       Despite researches related to the effects on skin, no sufficient research is currently available with regards to the safety threshold necessary to prevent any disorders that may occur on the cornea.

·       UV instruments may not only emit UV-C radiations as declared; however, may also emit UV-A and UV-B radiations in addition to UV-C, which increases the risk of skin cancer.

·       WHO strictly warns against direct contact with skin and eyes and against household use.

·       Although they are increasingly used for standard cleaning purposes in hospitals, there is still a lack of specific instructions manual and standard test procedure.

·       It is also recommended to use in integration with water treatment and air-conditioning units as they are not open for human
contact. Maintenance and similar personnel must be equipped with special protective eyewear, gloves and suits in such facilities. 

Adverse effects of UV-C radiations depend on the wave length, density and application times.

Current literature suggests that threshold limit values that prevent any risks on human health are available only for 254 nm radiations in details. Despite recently ongoing researches, authorized organizations have not yet revealed the UV-C
radiation dose required to prevent the reproduction of Covid-19 virus. 

It is not yet possible to make sure that Covid-19 viruses are completely destructible. Nevertheless, certain applications may be applied by adopting the values applicable to influenza and other viruses. The instruments must only emit declared wavelengths of radiation and their densities must have been measured and verified with a measuring device calibrated with the reference source of the same wavelength emitted.

Any deficiencies in standards and controls must be compensated within the shortest time to ensure accurate applications and densities and application times that may be effective on Covid-19 virus must be clearly explained. The spectrum of source must be defined for applications with LED and researches must be conducted according to all existing wavelengths.