Year

Accomplishment

1885

Duclaux [1] noted dissimilarities in sensitivity to sunlight among diverse species of bacterial spores.

1892

Geisler [1] demonstrated that UV radiation from sunlight and electric lamps was more efficacious in neutralizing microbes than longer wavelength radiation; nevertheless, he as well observed that the deadly impacts of longer wavelength radiation were boosted at augmented intensities.

1904-1905

Hertel et al. [1] were the premier to illustrate the mutagenic impacts of UV radiation.

1929

Gates [1] presented the premier analytical bactericidal action spectrum. Utilizing a mercury arc lamp, he generated the same shaped action spectra for Staphylococcus aureus and Bacillus coli, both with peak performance at 265 nm.

1930

Gates [1] announced an analytical bactericidal action spectrum with peak performance at 265 nm, very near to the 254 nm output of low-pressure Hg germicidal lamps.

1935

Wells and Fair [1] established that airborne infectious organisms can be efficiently destroyed in a short time employing aerosolized E. coli at 254 nm radiation in commanded circumstances.

1934-1955

Wells [1] suggested the idea of airborne infection via “droplet nuclei”―evaporated droplets carrying infectious microbes that could stay suspended in the air for prolonged times. Wells and Fair [1] established the capability of UVGI to efficaciously demobilize airborne microbes and demonstrated the notion of infection through the airborne pathway. They utilized upper-room UVGI to avoid the epidemic diffusion of measles. Overholt and Betts [17] widen the implementation of UVGI in hospitals by applying many dispositions of cubicle-like UVGI “light curtains” conceived to avert respiratory cross-infections. Whisler et al. [18] estimated the influence of physical and ecological parameters on UVGI performance, comprising humidity and air circulation―two key variables in the effectiveness of UVGI. The Council on Physical Therapy [19] agreed on UVGI for disinfecting targets. Hollaender and Oliphant [20] declared that the high UV Germicidal Irradiation for Air Disinfection vulnerability of several agents at around 260 nm is founded on the essential work of DNA in biological actions of organisms.

1957-1976

Riley et al. [21] revealed Guinea pigs to air emerging from an occupied tuberculosis (TB) ward and established that TB is diffused through the airborne pathway [22] [23] . Riley et al. [24] established that virulent tubercle bacilli and Bacillus Calmette-Guérin (BCG) are in the same manner vulnerable to UVGI and quantified the vanishing rate of aerosolized BCG in a model room with and without upper-room UVGI. Further, UVGI efficiently demobilized E. coli in the ward and stopped rabbits from developing TB. On the contrary, revealed rabbits were infected with TB without employing UVGI. Investigations have emphasized both that TB can easily be diffused via droplet nuclei and that UVGI can enough demobilize the infected air [25] [26] [27] . Beukers and Berends [28] revealed frozen solutions of thymine to UV-C radiation leading to the generation of thymine dimmers. McLean [29] blocked the diffusion of influenza in Veterans Hospital TB patients utilizing upper-room UVGI throughout the 1957 pandemic, presenting testimony for the airborne transmission of influenza. Riley et al. [21] examined the influences on disinfection rates in the lower room from air mixing via convection and a ceiling fan and mathematically modeled it. Riley and Kaufman [25] [27] followed the impact of relative humidity (RH) on the performance of UVGI, with an acute slop observed in the portion of organisms neutralized at RH estimates bigger than 60% to 70%.

1985?1992

UV-C wavelengths are the most biologically energetic radiation and, ironically, much less hazardous to human beings. This is due to the fact that UV-C radiation is absorbed by the outer dead layer of human skin, while UV-B and UV-A radiation infiltrate deeper. The contrast has to be performed among the biological effect and the infiltration depth of UV radiation, a fundamental notion in UVGI security in the direction of quantitatively assessing UVGI performance and integrity actions for the appropriate employment of UVGI [30] - [35] .

2001

Investigations estimating different ecological and physical variables on UVGI efficiency (like air mixing and ventilation, humidity, microbial vulnerability, fixture irradiance and configuration, and photo-reactivation) were performed [36] .

2004

The dielectric barrier has a crucial contribution in prevention of arcing and in the so-called non-thermal excitation of the plasma. Further, DBD produces uniform discharge plasma at atmospheric pressure [37] .

2010-2020

Plasma-based apparatuses have been assessed for biological sterilization. Cooper et al. [38] focused on the impact of plasma on Bacillus stratosphericus in three viability states (i.e., viable, cultivable at low plasma dose, and viable but non-cultivable (VBNC) at high plasma dose). B. stratosphericus possesses the capacity to turn into VBNC across plasma implementation. Yating et al. [39] examined the influence of atmospheric pressure non-equilibrium plasmas (APNPs) on N. gonorrhoeae. APNPs are apt to efficiently and rapidly neutralize the N. gonorrhoeae; further, the neutralizing impact is linked to the structural deterioration of the cell membrane. Employing non-thermal plasmas for disinfecting multidrug-resistant microorganisms such as S. aureus, Pseudomonas aeruginosa, and Candida albicans in environmental settings and substantiate ongoing clinical applications for plasma devices. Maisch et al. [40] assessed the influence of cold atmospheric plasma for numerous time periods or UVC radiation doses on D. radiodurans. They found D. radiodurans sensible to the cold atmospheric plasma treatment, identical to the methicillin-resistant Staphylococcus aureus (MRSA) strain. Conversely, D. radiodurans was more resistant than MRSA to UVC radiation treatment. Using cold plasma, Pan et al. [41] killed E. faecalis in vitro biofilms in dental root canal treatment, and Xu et al. [42] eliminated yeast cells in water.