farinae at difference exposure times and distances are shown in Table 1. Mortality rates for direct irradiation of D. pteronyssinus) and Dermatophagoides farinae ( D. The aim of this study is to investigate the mortalities induced by UV-C irradiation on eggs and adults of 2 species of HDM, Dermatophagoides pteronyssinus ( D. The implication that goes with those long lists is often made that UV-C will be just as effective on HDM. Long lists of bacteria, viruses and moulds also are often quoted to assert the killing power of UV-C. It is, however, difficult to make direct comparisons between studies as the level of UV dose achieved is not always stated and UV intensities vary with light sources. The efficacy of UV-C had been previously demonstrated against some stored product beetle and mite pests - with sensitivity varying with species and doses. High intensity UV light modifies proteins as well, so it is possible that UV light might render an allergen non-allergenic. Ultraviolet light air purification has been used for years by the medical field to sanitize rooms and equipment in order to prevent the spread of illness and disease. To date the UV-C is the wavelength in germicidal applications and is also recommended by the Centre for Disease Control and Prevention. Ultraviolet C (UV-C) is a short wavelength (100-280 nm) radiation and is primarily used for the disinfection of air, surfaces and liquids from microbial contaminants. Ultraviolet light is known to damage or kill living organisms because it will destroy the DNA by forming covalent bonds between certain adjacent bases in the DNA, thereby preventing further replication and growth. A number of other investigators also have considered the possibility of using UV rays to control, or at least to suppress development of various aeroallergens and insects. Wharton reported that UV irradiation (254 nm) killed nymphs of the American cockroach, Periplaneta americana. UV irradiation is widely used as a germicide and as an attractant for insects, in embryological physiological studies and for the surface disinfection of insect eggs. Physical strategies like irradiation has become an established technique for controlling aeroallergens because of residue free advantages over chemicals. Several chemicals have been examined in laboratories but their effectiveness in the home is controversial or even if effective, they have not been commercialized for home use because have potential problems of toxicity to non targets such as humans and pets, produce unpleasant odor, damage household items, and unable to penetrate deeply into carpet and upholstery. There are various approaches for the control of house dust mite and their allergen such as by reducing indoor relative humidity to below 50%, coupled with regular cleaning and use of encasement on mattress and pillows. Dermatophagoides farinae and Dermatophagoides pteronyssinus are considered among the most important pyroglyphid mites because of their cosmopolitan occurrence and abundance in homes. Pyroglyphid mites usually account for >90% of the mite population in houses. A number of the allergen producing HDM belongs to the family Pyroglyphidae. The HDM allergens cause allergic symptoms such as asthma and atopic dermatitis in atopic humans. The concern about HDM is that some species produce allergens affecting humans. They are microscopic, eight-legged creatures closely associated with us, but they are not parasitic and do not bite. House dust mites (HDM) are found in most homes.
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