Impact of High Solar UV Radiant Exposures in Spring 2020 on SARS-CoV-2 Viral Inactivation in the UK†.

Potential for SARS-CoV-2 viral inactivation by solar UV radiation in outdoor spaces in the UK has been assessed. Average erythema effective and UV-A daily radiant exposures per month were higher (statistically significant, P < 0.05) in spring 2020 in comparison with spring 2015-2019 across most of the UK, while irradiance generally appeared to be in the normal expected range of 2015-2019. It was found that these higher radiant exposures may have increased the potential for SARS-CoV-2 viral inactivation outdoors in April and May 2020. Assessment of the 6-year period 2015-2020 in the UK found that for 50-60% of the year, that is most of October to March, solar UV is unlikely to have a significant (at least 90% inactivation) impact on viral inactivation outdoors. Minimum times to reach 90% and 99% inactivation in the UK are of the order of tens of minutes and of the order of hours, respectively. However, these times are best case scenarios and should be treated with caution.

Survey of Home-Use UV Disinfection Products†.

The COVID-19 pandemic provided a commercial opportunity for traders marketing a range of ultraviolet (UV) radiation products for home-use disinfection. Due to concerns about the efficacy of such products and the potential for harmful levels of UV exposure to people, a range of products were purchased from on-line trading platforms. Spectral irradiance measurements were carried out to determine whether the products could be effective against the SARS-CoV-2 virus and whether they were likely to exceed internationally agreed exposure limits. It was concluded that many of the devices were not effective and many of those that were potentially effective presented a risk to users.

Opinion: To UV, or not to UV – That is the question

Opinion: To UV, or not to UV - That is the question The COVID-19 pandemic has seen a rush of initiatives to stem the spread of SARS-CoV-2, the coronavirus that causes the disease. UVR sources have been available for disinfection for many years, the main one being the low-pressure mercury lamp, with the primary emission at 253.7 nm in the UV-C part of the spectrum. [Extracted from the article] Copyright of Lighting Research & Technology is the property of Sage Publications, Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

SmartPDT®: Smartphone enabled real-time dosimetry via satellite observation for daylight photodynamic therapy.

BACKGROUND: Actinic keratosis (AK) affects one quarter of over 60  year olds in Europe with the risk of transforming into invasive squamous cell carcinoma. Daylight photodynamic therapy (dPDT) is an effective and patient preferred treatment that uses sunlight to clear AK. Currently, there is no standardised method for measuring the light received during treatment. METHODS: SmartPDT® is a smartphone-based application and web-portal, developed by siHealth Ltd, enabling remote delivery of dPDT. It uses satellite imagery and computational algorithms to provide real-time determination of exposure to PpIX-effective solar radiation ("light dose"). The application also provides forecast of expected radiant exposures for 24- and 48-hs prior to the treatment period. Validation of the real-time and forecasted radiant exposure algorithms was performed against direct ground-based measurement under all weather conditions in Chilton, UK. RESULTS: Agreement between direct ground measurements and satellite-determined radiant exposure for 2-h treatment was excellent at -0.1 % ± 5.1 % (mean ±â€¯standard deviation). There was also excellent agreement between weather forecasted radiant exposure and ground measurement, 1.8 % ± 17.7 % at 24-hs and 1.6 % ± 25.2 % at 48-hs. Relative Root Mean Square of the Error (RMSEr) demonstrated that agreement improved as time to treatment reduced (RMSEr = 22.5 % (48 -hs), 11.2 % (24-hs), 5.2 % (real-time)). CONCLUSION: Agreement between satellite-determined, weather-forecasted and ground-measured radiant exposure was better than any existing published literature for dPDT. The SmartPDT® application and web-portal has excellent potential to assist with remote delivery of dPDT, an important factor in reducing risk in an elderly patient population during the Covid-19 pandemic.