Dry-fog disinfection as a method for processing vehicles for passenger transport

Due to the corona pandemic, the demand for efficient and fast-acting disinfection measures is high. In this work, the disinfecting potential of a dry fogging technology (Apollon Biotech GmbH, Germany) was investigated for the possibility of disinfection of vehicles for passenger transport. This could represent a new approach for processing emergency vehicles or local passenger transport vehicles quickly and cost-effectively. A public bus was used as a model for a passenger transport vehicle (Ferienfahrschule Hense GbR, Germany). This vehicle was tested at predetermined points before and after dry-fog disinfection with swab and contact plate samples. In addition, contaminated sample tiles (Staphylococcus aureus ATCC 6538;5x104 CFU) were placed at some locations in order to be able to record a standardized germ reduction. To determine the decontamination effect of the air in the vehicle, active airborne germ measurements were performed. In the airborne germ measurement, our results indicated a reduction of approx. 68% of the microbiological air contamination. Screening of the total contamination of the bus at several selected sites showed an average load of approximately 348 CFU per test site. After disinfection, the average bacterial count was reduced to approx. 18 CFU per test site. This disinfecting effect could also be shown with the standardized test tiles. An efficiency level of between log 0.8 and 3.7 was obtained at the various test sites. © 2022 The Author(s), published by De Gruyter.

Health risk assessment of inhalation exposure to dry fogging of hydrogen peroxide in a dental clinic during the COVID-19 pandemic.

After the outbreak of COVID-19, many dental clinics use dry fogging of hydrogen peroxide (H2O2) to disinfect the air and surfaces. Inhalation of highly concentrated solutions of H2O2 may cause severe respiratory problems. This study aimed to estimate the health risk assessments of inhalation exposure to dry fogging of H2O2 in a dental clinic. This cross-sectional, descriptive-analytical study was performed to determine the inhalation exposure and health risk of 9 dental clinic staff with H2O2 in six rooms. Occupational exposure to H2O2 was assessed using the OSHA VI-6 method and a personal pump with the flow rate of 500 mL/min connected to the midget fritted-glass impinger containing 15 mL of TiOSO4 collecting solution. The health effects of H2O2 exposure were assessed using a respiratory symptoms questionnaire. The health risk assessment of inhaled exposure to H2O2 was also performed using the method provided by the Singapore occupational health department. The mean respiratory exposure of clinic staff to H2O2 was ranged from 1.3 to 2.83 ppm for six rooms which was above the limits recommended by international organizations. Dyspnea (44.4%), cough (33.3%), and nasal burning (22.2%) were the most prevalent health problems. The results also showed a medium risk for endodontics and surgery, and lower risk for periodontics, restorative care, orthodontics, and prosthetics. The results of this study indicate that when using an automated hydrogen peroxide-vapor fogger, calculating the spraying time based on room volume and using the rooms after 30 min of fogging is very important and can greatly reduce the risk ranking.

Airborne Disinfection by Dry Fogging Efficiently Inactivates Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), Mycobacteria, and Bacterial Spores and Shows Limitations of Commercial Spore Carriers.

Airborne disinfection of high-containment facilities before maintenance or between animal studies is crucial. Commercial spore carriers (CSC) coated with 106 spores of Geobacillus stearothermophilus are often used to assess the efficacy of disinfection. We used quantitative carrier testing (QCT) procedures to compare the sensitivity of CSC with that of surrogates for nonenveloped and enveloped viruses, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), mycobacteria, and spores, to an aerosolized mixture of peroxyacetic acid and hydrogen peroxide (aPAA-HP). We then used the QCT methodology to determine relevant process parameters to develop and validate effective disinfection protocols (≥4-log10 reduction) in various large and complex facilities. Our results demonstrate that aPAA-HP is a highly efficient procedure for airborne room disinfection. Relevant process parameters such as temperature and relative humidity can be wirelessly monitored. Furthermore, we found striking differences in inactivation efficacies against some of the tested microorganisms. Overall, we conclude that dry fogging a mixture of aPAA-HP is highly effective against a broad range of microorganisms as well as material compatible with relevant concentrations. Furthermore, CSC are artificial bioindicators with lower resistance and thus should not be used for validating airborne disinfection when microorganisms other than viruses have to be inactivated.IMPORTANCE Airborne disinfection is not only of crucial importance for the safe operation of laboratories and animal rooms where infectious agents are handled but also can be used in public health emergencies such as the current severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. We show that dry fogging an aerosolized mixture of peroxyacetic acid and hydrogen peroxide (aPAA-HP) is highly microbicidal, efficient, fast, robust, environmentally neutral, and a suitable airborne disinfection method. In addition, the low concentration of dispersed disinfectant, particularly for enveloped viral pathogens such as SARS-CoV-2, entails high material compatibility. For these reasons and due to the relative simplicity of the procedure, it is an ideal disinfection method for hospital wards, ambulances, public conveyances, and indoor community areas. Thus, we conclude that this method is an excellent choice for control of the current SARS-CoV-2 pandemic.