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Air Quality in Transit Buses (2023) / Chapter Skim
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Day 2 Session 1
Pages 26-33

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From page 26...
... On the other end of the spectrum, the bacteria that cause bacterial meningitis are larger and have a hard outer shell. Spores are much larger, and most, if not all, have hard outer shells; it would take a very high dose to inactivate spore DNA.
From page 27...
... Terminals and stations can use upper air lights to prevent the spread of infection where a lot of people are waiting for their transportation. Upper air disinfection relies on air currents coming from people's body heat and, as someone speaks or coughs, the pathogens are going to rise to the top of the space.
From page 28...
... John Gasparine discussed the range of bolt-on technologies that could be considered for existing HVAC systems or newly designed HVAC systems. There are three categories of technologies: technologies that agencies can consider for reducing the risk of airborne diseases; technologies that are helpful for other aspects of air quality, but not necessarily helpful for reducing the risk of airborne disease; and technologies that are either not well studied or that can pose unintended safety risks to customers and transit workers.
From page 29...
... Again, it is best to consult a public health professional, in particular an environmental engineer, to help discern which of these technologies are going to help to achieve an air quality goal. Vaporized hydrogen peroxide devices nebulize liquid hydrogen peroxide into the air, and then people breathe in the liquid hydrogen peroxide.
From page 30...
... Some of these black lights claim to help kill biological pathogens, but this is not well documented, so more study is needed to understand both the safety risks and efficacy. UV-C wavelength 222, also called "far UV-C" in laboratory conditions, seems to help accelerate the degradation of COVID-19 in laboratory conditions and offer lower risk for eye or skin exposure.
From page 31...
... EPA has been focused on developing standard test methods that can be used to compare across technology types or within a technology. EPA has been using specialized facilities within the EPA labs in North Carolina, utilizing a large, 3,000–cubic foot test chamber that controls temperature and humidity and a mock HVAC system that is fully recycling the air in the test chamber.
From page 32...
... There is inherent bias variability in working with these microorganisms, particularly in the air, so replicate testing is important. Ratcliff noted that in another set of three replicates, in which EPA ran the test with the electrostatic filter component active, there was more virus removed from the chamber air more quickly than in the control tests.
From page 33...
... Freedman commented that people seem to gravitate toward large reductions as being more effective, regardless of the speed and time, and that there is room for improvement in the communication of these results so that field users can more intuitively understand the relative effectiveness between a product and a different intervention, such as improving dilution ventilation by opening a window.


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