Wladyslaw J. Kowalski

Sanuvox · Research & Development

Ultraviolet Rate Constants for Human Pathogenic Bacteria

Ultraviolet Rate Constants for Human Pathogenic Viruses

A review of the ultraviolet susceptibility of Langya Henipavirus.

The effects of ultraviolet light on allergens

Monolayers of bacterial cells of Staphylococcus aureus and Pseudomonas aeruginosa were inoculated on glass slide carriers using an automated inoculum spray deposition system. The use of bacterial monolayers allows for control of critical variables for testing and verification of light-based disinfection technologies. This approach avoids the variab...

The Panzootic of Avian Influenza

First aid for UV overexposure

A review of the ultraviolet susceptibility of Adenovirus, and epidemiology.

In the legal cannibis sector, unwanted microbes in the airstream can translate to big investments going up in smoke.

Ultraviolet Light Disinfection for animal facilities.

This report addresses a topic of high current interest - the ultraviolet susceptibility of SARS-CoV-2, the virus that causes COVID-19 disease. The results of a literature review are presented and summarized to provide a basis for estimating the ultraviolet susceptibility of SARS-CoV-2, and relevant supplemental information is provided on COVID-19 b...

This spreadsheet demonstrates the Cluster Model of Ultraviolet Disinfection and can be used to fit any data set with or without a shoulder and with or without a tail. It will provide parameters defining the degree of clustering and will estimate the Intrinsic UV Rate Constant. It requires input in terms of the microbe mean diameter and must be used...

Aims: To develop a new mathematical model derived from first principles to define the kinetics of ultraviolet disinfection and to explain the phenomenon known as tailing. The theory presented interprets tailing as the result of photoprotection due to cumulative Mie scattering effects in clustered populations of microorganisms. Methods and results...

A focused multivector ultraviolet (FMUV) light system was used in a parallel process with manual chemical disinfection during operating room (OR) turnovers to assess the impact on cleaning time. The average time to disinfect an OR using only chemical wipes and mops was 19.0 minutes (n = 68); for the FMUV process, the average time was 18.8 minutes (...

Aerobiological engineering is the art and science of designing buildings and systems for the control of airborne pathogens and allergens in indoor environments, including commercial buildings, hospitals, and residences. Aerobiology is the study of microorganisms in the air that may be detrimental to human health. Included among these organisms are...

A primer on mold problems in buildings.

Background: The aim of this study was to evaluate the performance of a focused multivector ultraviolet (FMUV) system employing shadowless delivery with a 90-second disinfection cycle for patient care equipment inside and outside the operating room (OR) suite without manual-chemical disinfection. Methods: A 5-point multisided sampling protocol was u...

Abstract This study investigated the ability of monochromatic ultraviolet (UV) light at 254 nm applied at typical drinking water disinfection doses to damage the antibiotic-resistant genes mph(A), sul1, tet-A, and bla-Tem1 in waterborne bacteria. UV sensitivity rank was bla-TEM1 > tet-A > sul1 > mph(A), which is consistent with predictions of a pre...

Surrogates of Candida auris are used as a basis to estimate the UV susceptibility of Candida auris.

The ultraviolet (UV) sensitivity of viruses, bacteria, fungi, and other microorganisms has been established by clinical testing in hundreds of published studies and has been related to the genomic sequences of DNA or RNA (Kowalski 2009). Recently, the UV sensitivity of individual genes that impart antibiotic resistance (ABR) to bacteria was clinica...

There is a connection between ultraviolet light disinfection and cancer genomics. This report explores the relationship between these two subjects with the intent of developing a quantifiable mathematical relationship that may provide insight into cancer and lead to the development of a cancer prediction index. There are several major causes of mut...

This report examines the susceptibility of codons and amino acids to single nucleotide substitutions based on ultraviolet genomics. Results suggest that evolution may have generated redundancy in the genetic code as a hedge against the mutability of codons that are pyrimidine-rich.

A review of the effectiveness of dilution ventilation, filtration, and ultraviolet germicidal irradiation in mitigating five biological-weapon agents and Bioterrorism Defense

A comparison is made of the genomic parameters of Influenza A viruses H1N1, H2N2, H3N2, H5N1, H7N9, and Influenza C, C and D viruses based on their complete genomes. Table 1 summarizes the genomic parameters and these include counts of the base pairs, counts of the dimer pairs, counts of the hyperchromic (h) pairs, and the number of Clusters and Me...

This study investigated the potential to use genomic modelling to identify future viral surrogates for the purposes of UV reactor validation. The need for readily available and easily cultured bacteriophage led to a search of the American Type Culture Collection (ATCC) and Felix d’Herelle organism collections and the identification of 182 `Hazard G...

Ultraviolet genomic modeling is a method for evaluating the ultraviolet sensitivity of microorganisms by reading and interpreting the complete microbial genome. Base counting software is used to identify short sequences of amino acids that have a high photodimerization potential. The specific sequences that can result in photodimers include thymine...

Ultraviolet genomic modeling is a method for evaluating the ultraviolet sensitivity of microorganisms by reading and interpreting the complete microbial genome. Base counting software is used to identify short sequences of amino acids that have a high photodimerization potential. The specific sequences that can result in photodimers include thymine...

This book is a comprehensive source for technical information regarding ultraviolet germicidal irradiation (UVGI) and its application to air and surface disinfection for the control of pathogens and allergens. The primary focus is on airborne microbes and surface contamination applications for hospitals, commercial facilities, and residential homes...

Ultraviolet Germicidal Irradiation (UVGI) is electromagnetic radiation that can destroy the ability of microorganisms to reproduce by causing photochemical changes in nucleic acids. Wavelengths in the UVC range are especially damaging to cells because they are absorbed by nucleic acids. The germicidal effectiveness of UVC peaks at about 260–265 nm....

The disinfection of surfaces is perhaps the simplest and most predictable application of ultraviolet germicidal radiation. UV is highly effective at controlling microbial growth and at achieving sterilization of most types of surfaces. Early applications included equipment sterilization in the medical industry. Modern applications include pharmaceu...

Various applications for UVGI exist in the field of bioterrorism defense, or biodefense, including air disinfection, surface disinfection, material disinfection, and remediation of the aftereffects of a bioweapon attack. The specific types of microbes that may be used as biological weapons are finite in number and are addressed here insofar as they...

Pulsed light systems using ultraviolet wavelengths have been shown to rapidly produce high levels of disinfection. The rate of disinfection is high due to the extreme UV power levels produced by pulsed UV lamps. The disinfection effect of pulsed light is primarily due to the UV content and can be modeled using the same basic UV rate constants previ...

Many types of UVGI systems and equipment are currently available for air and surface disinfection applications. These systems include lamps, fixtures, and ballasts, and often include reflective surfaces to enhance the irradiance field. Various other components may form part of more complete systems, including filters, light baffles, and UV-absorbin...

A variety of guidelines and standards are available or under development that provide information on engineering design, applications, and safety considerations for air and surface disinfection UVGI systems. Guideline documents have been issued by government institutions, professional organizations, and by some private sources. Some of them merely...

UVGI air disinfection systems that operate on airstreams have applications in hospitals, schools, commercial buildings, homes, and in many other facilities. There are two main types forced air UV disinfection systems: In-duct UV systems and stand-alone recirculation units (also called unitary UV systems). A third class of systems exist, barrier sys...

Ultraviolet exposure can cause a number of secondary effects on materials as a result of photochemical reactions and heat. These effects include solarization, photodiscoloration, photodegradation, damage to plants, and generation of ozone, which can itself degrade materials. These secondary effects are of concern to UVGI applications such as in-duc...

UVGI systems can be implemented in the various types of buildings in which people live to reduce the transmission of pathogens and to control the levels of allergens. Living accommodations vary from single unit houses to large condominiums and apartments where thousands of people may live. In houses and apartments with separate ventilation systems,...

Ultraviolet germicidal irradiation (UVGI) used for the disinfection of air and surfaces is biocidal to microorganisms but presents a variety of potential health hazards to humans as well, including eye damage, skin burns, and even has the potential to cause skin cancer. Because germicidal UV rays are invisible to the eye, humans may be subject to h...

Applications for UVGI systems in commercial buildings vary with the type of building, but virtually every type of building can benefit from the use of in-duct air disinfection and many buildings can benefit from the use of other types of UV systems. The health hazards and microbiological problems associated with various types of commercial building...

This chapter addresses applications of ultraviolet germicidal irradiation (UVGI) in health care facilities, including laboratories and animal or veterinary facilities. This chapter does not review the applicable guidelines or standards for air quality in these facilities, which typically do not mention UVGI, but the references and Chapter 11 may be...

Upper Room UV systems, sometimes called Upper Air systems, create a germicidal zone of UV rays that are confined to the upper portion of a room, known as the UV zone or stratum. Air that enters into this field is disinfected, along with any exposed surfaces. UV exposure levels in the lower room are maintained below the ACGIH 8-hour exposure limit o...

Microbiological testing methods are the best means of verifying the effectiveness of ultraviolet germicidal irradiation systems. Testing may involve the irradiation of bacteria or fungi on surfaces or petri dishes, or it may involve airborne testing of bacteria and fungi inside UVGI units, ducts, or in buildings. Sampling methods for air and surfac...

Mathematical modeling of the UV disinfection process provides a basis for sizing ultraviolet disinfection equipment and for interpreting test results. It also allows for adaptation of UV systems to specific disinfection processes and for the disinfection of specific microorganisms. Disinfection is generally modeled in terms of the survival, or its...

The modeling of systems for air and surface disinfection can be used to assess the UV dose, which can then be used to determine disinfection rates for specific microbes. The modeling of UV irradiance fields can produce fairly accurate results for the purposes of system sizing. Several components in UV disinfection systems may require modeling – the...

The ultraviolet (UV) lamp is the most critical component of any UVGI air or surface disinfection system. UV lamps come in many shapes, sizes, and UV output power levels, and they may produce different spectral bands of germicidal UV. All germicidal UV lamps will produce light wavelengths of either UVC (100–280 nm), UVB (280–320 nm), or both (UVC/UV...

Testing of Ultraviolet Germicidal Irradiation (UVGI) systems encompasses both irradiance measurement of UV lamps and UV dose measurements, which is a field known as radiometry. Measurement of individual UV lamp irradiance is often performed in the factory before, during, or after burn-in of the lamps. Traditionally the minimum testing required has...

Microbial susceptibility to ultraviolet light varies widely between species of microbes. Bacteria, viruses, and fungal spores respond to UV exposure at rates defined in terms of UV rate constants. Other parameters used to define UV susceptibility include the Z value or Z eff (same as UV rate constant), the inactivation cross-section, the D 90 (UV d...

A mathematical model is presented for the ultraviolet susceptibility of microbes based on evaluation of complete genomes. The genomes of 49 animal viruses and bacteriophages, and 33 bacteria, were analyzed using base-counting software to establish the frequencies of potential dimers. A total of 71 data sets represented 27 ssRNA viruses, while 77 da...

A mathematical model is presented to explain the ultraviolet susceptibility of viruses in terms of genomic sequences that have a high potential for photodimerization. The specific sequences with high dimerization potential include doublets of thymine (TT), thymine-cytosine (TC), cytosine (CC), and triplets composed of single purines combined with p...

The susceptibility of viruses to ultraviolet (UV) light has traditionally been defined in terms of the UV rate constant, also called a Z value, which is the slope of the survival curve on a logarithmic scale. The UV rate constant refers to either broad range UV in the UVB/UVC spectrum (200-320 nm) or, more commonly, to narrow-band UVC near the 253....

Pathogenic microorganisms that have developed resistance to antibiotic treatment and have begun to spread beyond the bounds of health care setting are discussed. The most dangerous are those that may spread by the airborne route, which include methicillin-resistant Staphylococcus aureus (MRSA) and multidrug-resistant tuberculosis (XTB). Once these...

The epidemiology and aerobiological pathways of airborne nosocomial infections and reviewing air and surface disinfection technologies, including ultraviolet germicidal irradiation (UVGI), are discussed. Air recirculation is permitted in most hospital areas, including operation rooms (ORs) and intensive-care units (ICUs). ORs have an air-change rat...

Some critical issues related to indoor-air-quality (IAQ) are presented along with their salient solutions. Some contemporary indoor-air-quality problems affecting the health and comfort of occupants and the progresses made towards laws and legislations related to IAQ are also presented. The development of 62.2 and 62.1 versions of the ANSI/ASHRAE S...

A model for predicting the ultraviolet (UV) irradiance field inside specularly reflective rectangular ultraviolet germicidal irra-diation (UVGI) air disinfection systems is developed based on a view factor model of the UV lamps and a virtual image model of the specular reflections. The combined three-dimensional irradiance field, direct and reflect...

A dimensional analysis of an ultraviolet germicidal irradiation (UVGI) air disinfection system within a diffusely reflective enclosure is performed using the Buckingham pi theorem. The eight dimensionless parameters obtained include the duct aspect ratio, the lamp aspect ratio, the reflectivity, and terms that incorporate the UV dose, airflow, duct...

This paper presents the results of research on the performance of air-cleaning and air-disinfection systems used for protecting buildings against intentional releases of biological agents. The air-cleaning technologies addressed include dilution ventilation, filtration, and ultraviolet germicidal irradiation. A 40-story commercial office building i...

An enclosed flow-through system using airborne ozone for disinfection and which removes the ozone with a catalytic converter was tested with a strain of Escherichia coli. Petri dishes containing the microorganisms were inserted in a chamber and exposed for 10-480 min to ozone concentrations between 4 and 20 ppm. Death rates in excess of 99.99% were...

We here present a review of the problem of controlling airborne disease transmission in animal research facilities, with emphasis on engineering design and air-treatment technologies. Dilution ventilation, pressurization control, source control, and air disinfection and removal systems are reviewed, and analytical studies on the effects of dilution...

In this article a modified single fiber model of filtration is described and used to generate filter performance curves that can be fit to MERV data in the 0.3-10.0 micron size range and that can be extended down to the size range of viruses. Coupled with the summary of logmean diameters of airborne microorganism included here, these models will en...

Multizone network airflow analysis is used to analyze stack and mechanical system effects on the distribution of three representative biological agents in a prototype 40 story building. This approach relies on mass balances to compute airflow and contaminant transfer between the building zones. The analysis considers stack effects caused by cold ou...

The critical aspects of filter sizing and a methodology for predicting a filter's performance against allergens, bacteria and viruses are presented. The use of 80- and 90-percent filters produces air-quality improvements that approache those with HEPA filters. The combination of filtration and UVGI offers an efficient way of controlling both the la...

Mathematical models of the response of populations of microorganisms exposed to ultraviolet germicidal irradiation (UVGI) are developed that include two-stage response curves and shoulder effects. Models are used to develop a C++ computer program that is capable of predicting the performance of UVGI air disinfection systems. The algorithms are base...

A comprehensive treatment of the mathematical basis for modeling the disinfection process for air using ultraviolet germicidal irradiation (UVGI). A complete mathematical description of the survival curve is developed that incorporates both a two stage inactivation curve and a shoulder. A methodology for the evaluation of the three-dimensional inte...

This paper summarizes an improved methodology for predicting the rate of airstream disinfection for UVGI systems that will enable effective designs and lower energy costs. This approach uses radiative view factors to define the three- dimensional intensity field for lamps and reflective surfaces inside enclosures. Lamp photosensor data for a variet...

The factors that determine the design parameters of ultraviolet germicidal irradiation (UVGI) systems are addressed. The methods that can be used to size systems more effectively are discussed. The information presented may lead the industry back to the path of continuous improvement although the goal of eliminating airborne disease might remain un...

The filtration of airborne particulates has been studied extensively and removal efficiencies can be adequately predicted from theory or from catalog data. The filtrations of airborne microorganisms, however, has not been specifically addressed by theory and has seen limited empirical study. This paper addresses the variety of factors that may caus...

The bactericidal effects of high concentrations of airborne ozone were tested against Escherichia coli and Staphylococcus aureus. Petri dishes containing the microorganisms were inserted in a chamber and exposed for 10 - 480 seconds to ozone concentrations between 300 and 1500 ppm. Death rates in excess of 99.99% were achieved for both species. The...

Airborne transmission of respiratory disease in indoor environments remains a problem of indoor air quality with few engineering alternatives and for which performance goals and design parameters unclear. This paper summarizes the relevant literature of medical microbiology and aerobiology in a manner that engineers may find useful in designing a H...

Ultraviolet Germicidal Irradiation (UVGI) systems for air disinfection are coming into increasing use for indoor air quality, disease control, and biodefense applications. However, there are currently no consensus standards for the design, application, or testing of UVGI systems. Several agencies are currently investigating development of guideline...