![]() The most striking divergence occurred during the spring of 1941 when measles swept through schools around Philadelphia. In the 1930s, the first upper-room ultraviolet fixtures were installed around Philadelphia.ĭuring five years of experiments at several schools there, students in classrooms outfitted with ultraviolet fixtures were less likely to catch and spread some contagious diseases, such as smallpox and mumps. “They’re not plug in and walk away forever,” Dr. The systems also add to electricity bills and require cleaning and maintenance. Bahnfleth, a professor of architectural engineering at Pennsylvania State University. “You’ve killed it essentially,” said William P. ![]() Ultraviolet light mangles the genetic material in pathogens - DNA in bacteria and fungi, RNA in viruses - preventing them from reproducing. A different frequency of ultraviolet might be even safer, even when it shines directly on people, which would also allow disinfection of surfaces. Ceiling fans are sometimes installed to draw air upward so that floating bacteria, viruses and fungi are zapped more quickly. ![]() Nardell describe, fixtures mounted on walls or ceilings, similar to fluorescent lights used today, shine ultraviolet light across the top of an interior space, well above people’s heads. Portable ultraviolet units are already being used to sterilize surfaces in hospital rooms and subway cars, but these can be used only when those spaces are unoccupied. This is not what President Trump incomprehensibly described in April when he suggested irradiating the insides of Covid-19 patients with ultraviolet light.
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