Ultraviolet (UV) light from the sun is one of the ways in which viruses are destroyed in nature; for example, coronaviruses (such as feline coronavirus) and avian influenza viruses are rapidly destroyed outdoors in the feces of free-ranging cats and chickens. Avian influenza pandemics have occurred regularly only since the rise of factory farms in the 1970s. The highly pathogenic avian influenza virus strain H5N1 is destroyed by UV rays from the sun in 30 minutes; however, it can survive for up to 5 days in moist poultry feces at ambient temperature, and up to 8 weeks at 4°C. The increasing frequency of pandemics of newly emerging diseases has been attributed to intensive farming practices (eg, overcrowding); while disinfection can somewhat mitigate those outbreaks, they will not stop until these poor farming practices are changed.
UV-B radiation (range 280–320 nm) and UV-C radiation (typically 254 nm) have been studied for their potential ability to disinfect water, food preparation surfaces, plasma for transfusions, and hospital rooms. Devices that emit UV-C radiation can decrease the population of some important pathogens (eg, Clostridioides difficile and vancomycin-resistant enterococci, but not appreciably Acinetobacter) in real-world settings such as hospital rooms.
