C+S February 2021 Vol. 7 Issue 2 (web)

towards inside venues only. There are many retrofit solutions that can play a role in infection mitigation which can be implemented almost immediately. HEPA Filtration Implementing HEPA filtration at the air handling unit can be very ef- fective in capturing and removing viruses from air streams, as long as they pass through the filter. However, because HEPA filters are typi- cally installed in the ductwork and therefore must rely on the airflow patterns to carry contaminants to the filter, small particles like viruses can circulate in the space for an extended period of time before eventu- ally making their way to the filter for capture. In general, while highly effective and reliable, an in-duct HEPA filter is more appropriate in preventing cross contamination between spaces than it is in guarantee- ing removal of contaminants from a given space. Ultraviolet (UV) Sterilization UVc, with a wavelength between 200–280 nm, is a band of ultraviolent light that has proven to be the most effective for infection control while inflicting minimal damage to people; however direct exposure still is not recommended. There are many novel applications of “in-room” UV sterilizers from stationary lights to portable devices mounted on robots for off hour surface sterilization. Given the proper contact time and intensity, UV can be an efficient method to inactivate viruses and bacteria — rendering them harmless. Able to be installed within an air handling unit or directly in the space it- self, UV is only effective, though, if the pathogen comes in direct contact with the light. Just as we discussed with HEPA filtration, if the UV lamp is installed within the air handling unit, the system relies on the airflow patterns to carry contaminants to it. In-room or upper air configurations can affect particles that have not made it to through the HVAC system, but these systems must be properly designed with either occupancy sen- sors of other safeguards to avoid exposing fans or employees. Bipolar Ionization Air Purification Bipolar ionization generators create positively and negatively charged oxygen ions which bind to contaminants in the indoor air, either caus- ing them to drop out of circulation in the room or to be captured by a mechanical filter within an air handling unit. When properly installed,

process that does not create overcrowding. Pre-packaging the food for pick-up will also help prevent lines from forming and droplet infection between patrons picking their food up or waiting for it to be prepared. Providing real-time information like this will help fans navigate their options without missing a minute more than necessary of the action. Restrooms pose similar issues as concession stands in terms of lines. To help keep the number of people down at any restroom, venue opera- tors can consider implementing technology that can show the number of people waiting or the estimated the wait time and even where under- utilized restrooms are located. Airborne Transmission HVAC systems play a large role in combatting airborne transmission, especially in areas where large groups of people gather, such as in a convention center hall or the arena bowl/concourse. While there are several technologies that can be implemented, we also know that tem- perature, humidity, air-movement, and direct sunlight all play a role in the longevity and infection potential for all three vectors. In general, our recommendation is to keep spaces between 40 and 60 percent rela- tive humidity, decreasing the time the virus can live on surfaces and keeping the virus from embedding in your lungs which is a greater concern in drier air. We also know that air movement, especially out- doors, limits the exposure to the virus through airborne particles. Because of the inherent differences between outdoor and indoor venues, we will assume that the following technologies are geared




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