Development of a Protocol for the Determination of the Ultraviolet Sensitivity of Microorganisms Suspended in Air

Ke, Qing Sheng; Craik, Stephen A.; El-Din, Mohamed Gamal; Bolton, James R.

doi:10.1080/02786820802616893

Cited by 11 publications

(6 citation statements)

References 9 publications

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“…The values range considers the different variants of the same pathogen. Organism Species Type Range (J/m ) (J/m ) Virus Adenovirus dsDNA – 59 116 Coronavirus ssRNA – 3 116 SARS-CoV-2 ssRNA – 5 117 Coxsackie ssRNA – 21 27 Influenza A ssRNA – 19 27 Bacteria Bacillus subtilis Veg – 14 118 Sp 149 119 Burkholderia cepacia Veg – 22 120 Escherichia coli Veg – 11 121 Francisella tularensi s Veg – …”

Section: Resultsmentioning

confidence: 99%

Solar ultraviolet light collector for germicidal irradiation on the moon

Lombini

Schreiber

Albertini

et al. 2023

Sci Rep

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Prolonged human-crewed missions on the Moon are foreseen as a gateway for Mars and asteroid colonisation in the next decades. Health risks related to long-time permanence in space have been partially investigated. Hazards due to airborne biological contaminants represent a relevant problem in space missions. A possible way to perform pathogens’ inactivation is by employing the shortest wavelength range of Solar ultraviolet radiation, the so-called germicidal range. On Earth, it is totally absorbed by the atmosphere and does not reach the surface. In space, such Ultraviolet solar component is present and effective germicidal irradiation for airborne pathogens’ inactivation can be achieved inside habitable outposts through a combination of highly reflective internal coating and optimised geometry of the air ducts. The Solar Ultraviolet Light Collector for Germicidal Irradiation on the Moon is a project whose aim is to collect Ultraviolet solar radiation and use it as a source to disinfect the re-circulating air of the human outposts. The most favourable positions where to place these collectors are over the peaks at the Moon’s poles, which have the peculiarity of being exposed to solar radiation most of the time. On August 2022, NASA communicated to have identified 13 candidate landing regions near the lunar South Pole for Artemis missions. Another advantage of the Moon is its low inclination to the ecliptic, which maintains the Sun’s apparent altitude inside a reduced angular range. For this reason, Ultraviolet solar radiation can be collected through a simplified Sun’s tracking collector or even a static collector and used to disinfect the recycled air. Fluid-dynamic and optical simulations have been performed to support the proposed idea. The expected inactivation rates for some airborne pathogens, either common or found on the International Space Station, are reported and compared with the proposed device efficiency. The results show that it is possible to use Ultraviolet solar radiation directly for air disinfection inside the lunar outposts and deliver a healthy living environment to the astronauts.

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Section: Resultsmentioning

confidence: 99%

Solar ultraviolet light collector for germicidal irradiation on the moon

Lombini

Schreiber

Albertini

et al. 2023

Sci Rep

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“…In the repair-deficient case, the simple exponential decay in fluence is mathematically equivalent to the binomial probability if the units are simply changed from joules per unit area to photons per unit area. In the repair-capable case, the multitarget expression, especially with noninteger shoulder parameter, is not mathematically equivalent to expressions with fixed integer n , such as a series event or a cumulative binomial distribution, and derived decay constants can differ by as much as a factor of 2 or 3 [see the discussion above comparing the results of Ke et al (2009) and Lim and Blatchley (2009) for B. subtilis strain ATC6633]. As a result, the estimates obtained by simple unit change of the multitarget decay constants may be less than those obtained by simple conversion of the data given in C2002, as shown here in Table 4.…”

Section: Resultsmentioning

confidence: 99%

“…The value of the decay constants obtained using a multitarget versus series event can differ by as much as a factor of 2 or 3 [e.g., Ke et al (2009) report a multitarget-derived k = 0.15 cm 2 /mJ, and Lim and Blatchley (2009) report a series-event-derived k = 0.53 cm 2 /mJ for the same strain B. subtilis (ATC6633) in air at the same humidity exposed to narrow band ultraviolet-c (UVC) [254 nm]). For B. subtilis , the sensitive, repair-deficient strain exponential decay in narrow band exposures ranges from ∼3 to 20 times faster than the exponential decay region of the repair-capable strain, depending on wavelength (M91).…”

Section: Methodsmentioning

confidence: 99%

Predicting Inactivation of Bacillus subtilis Spores Exposed to Broadband and Solar Ultraviolet Light

Handler

2019

Environmental Engineering Science

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This study develops general predictive models for the ultraviolet (UV) radiation dose–response behavior of Bacillus subtilis spores to solar UV irradiation that occurs in the environment and broadband UV irradiation used in water disinfection systems. The approach is demonstrated using previously obtained experimental survival rates for B. subtilis spores deposited on dry surfaces as well as in water and exposed to both narrow band UV radiation as well as broadband UV irradiation from solar exposure and disinfectant lamps. Results are modeled to derive predicted survival rates for spores as a function of irradiance intensity and wavelength, capability for repair, and depletion of available sites for UV damage. The essential features of the approach are expression of the inactivation action spectrum in terms of the probability of an incident photon being absorbed and forming a dimer lesion, and expression of the spore survival as a cumulative binomial distribution for damage. The results provide increased accuracy in estimating dispersed biological hazards, and evaluating the effectiveness of UV air and water disinfectant systems. In addition, the approach for the first time explains the observed reduced inactivation rate in a repair-capable strain compared with a sensitive, repair-deficient strain by accounting for the depletion of available lesion-forming sites due to increasing DNA damage.

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“…The present research aims at the development of a rigorous modeling, based on theoretical concepts and engineering principles in order to accurately incorporate the radiation field into the kinetic expressions of airborne microbial inactivation. In addition, the approach used of a continuous flow reactor is closer to real-life applications rather than batch approaches (Ke et al 2009) or surface deposited microorganisms (Handler 2016). A key aspect of the model is the application of an analogy between chemical and biological targets.…”

Section: Introductionmentioning

confidence: 99%

Dose estimation methodology for the UV inactivation of bioaerosols in a Continuous-Flow reactor

Retamar

Passalía

Brandi

et al. 2018

Aerosol Science and Technology

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Indoor air microbial pollution may be responsible for various human allergies and diseases. To reduce exposure, airborne bacteria can be directly controlled through devices that employ ultraviolet-C (UV-C) radiation. In this study, a continuous annular photo-reactor was used to evaluate the inactivation dose for two species: Gram-negative Escherichia coli and Pseudomonas aeruginosa. In order to provide meaningful results, a comprehensive kinetic modeling was performed, which included the evaluation of optical properties of the microorganisms and the calculation of radiation field inside the reactor. In this way, intrinsic inactivation rates could be obtained. From the reactor modeling and the experimental data sets, the first order inactivation rate or UV susceptibility for E. coli was 0.1055 m 2 J À1 , while for P. aeruginosa the obtained value was 0.2579 m 2 J À1 . The approach used allows a straightforward scaling-up of the process for real applications and microorganism species involved.

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Development of a Protocol for the Determination of the Ultraviolet Sensitivity of Microorganisms Suspended in Air

Cited by 11 publications

References 9 publications

Solar ultraviolet light collector for germicidal irradiation on the moon

Solar ultraviolet light collector for germicidal irradiation on the moon

Predicting Inactivation of Bacillus subtilis Spores Exposed to Broadband and Solar Ultraviolet Light

Dose estimation methodology for the UV inactivation of bioaerosols in a Continuous-Flow reactor

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