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Indoor air quality
Published in Abhishek Tiwary, Jeremy Colls, Air Pollution, 2017
Each person can shed as much as 1 g of skin cells each day, and this constitutes the organic matter for the domestic micro-ecology, regardless of the additional supply from pets, foodstuffs etc. The skin scales accumulate in furniture, carpets and bedding, where they are colonised by saprophytic fungi, and in turn by mites. The latter 300 μm arthropods (Dermatophagoides, which means skin-eater) enjoy conditions of 25°C and 70–80% relative humidity, and grow from egg to adult in 25 days. Hence their abundance has been favoured over the last 50 years by increased use of central heating (which raises temperatures), combined with reduced ventilation (which increases humidity) and use of fitted deep-pile carpets (which reduces cleanability). Floor or mattress dust samples typically contain 100–1000 mites (dead or alive) g–1. Mite faeces, which are sticky pellets about 20 μm in diameter, constitute a large proportion of the allergen in house dust. The gastric enzymes produced by the mites, which are in their faeces and are strong human allergens, become airborne and are eventually inhaled. The concentrations of the two specific allergenic proteins are in the range 2–10 μg (g settled dust)–1 or 5–50 ng m–3 air in the houses for which house dust mite allergy has been implicated in triggering an asthma attack. Corresponding allergens are produced by cats (Fel d), dogs (Can f) and cockroaches (Bla g). Again, the concentrations and inhalation rates are increased by the use of tighter buildings with better draught-proofing and reduced ventilation. The allergic response may be a gentle ‘runny nose’ of little concern, but it may also be associated with a violent or even fatal asthma attack. Although specific materials are related to sources – cat allergen concentrations are naturally higher in homes with cats, for example – there may be high enough concentrations in adjacent properties, or in trains and other public places, to cause reactions in sensitive individuals.
Indoor air quality
Published in Abhishek Tiwary, Ian Williams, Air Pollution, 2018
Each person can shed as much as 1 g of skin cells each day, and this constitutes the organic matter for the domestic micro-ecology, regardless of the additional supply from pets, foodstuffs, and so on. The skin scales accumulate in furniture, carpets and bedding, where they are colonised by saprophytic fungi, and in turn by mites. The latter 300 µm arthropods (Dermatophagoides, which means skin-eater) enjoy conditions of 25°C and 70%–80% relative humidity, and grow from egg to adult in 25 days. Hence their abundance has been favoured over the last 50 years by increased use of central heating (which raises temperatures), combined with reduced ventilation (which increases humidity) and use of fitted deep-pile carpets (which reduces cleanability). Floor or mattress dust samples typically contain 100–1000 mites (dead or alive) g−1. Mite faeces, which are sticky pellets about 20 µm in diameter, constitute a large proportion of the allergen in house dust. The gastric enzymes produced by the mites, which are in their faeces and are strong human allergens, become airborne and are eventually inhaled. The concentrations of the two specific allergenic proteins are in the range 2–10 µg (g settled dust)−1 or 5–50 ng m−3 air in the houses for which house dust mite allergy has been implicated in triggering an asthma attack. Corresponding allergens are produced by cats (Fel d), dogs (Can f) and cockroaches (Bla g). Again, the concentrations and inhalation rates are increased by the use of tighter buildings with better draught-proofing and reduced ventilation. The allergic response may be a gentle runny nose of little concern, but it may also be associated with a violent or even fatal asthma attack. Although specific materials are related to sources – cat allergen concentrations are naturally higher in homes with cats, for example – there may be high enough concentrations in adjacent properties, or in trains and other public places, to cause reactions in sensitive individuals.
Rhinitis in Japanese students – associations with window pane condensation, recent indoor painting, wooden home and dog allergen at school
Published in International Journal of Environmental Health Research, 2022
Motoko Takaoka, Kyoko Suzuki, Dan Norbäck
The study has some limitations. The number of schools and the number of students were limited. This limits the statistical power of the study, but since rhinitis is a common disease even a relatively small study can give reasonable statistical power. Outdoor air pollution is a well-known risk factor for rhinitis. We did not measure outdoor air pollution in our study, but data from the local monitoring station showed relatively low levels of outdoor air pollution in Kobe. Another limitation is that we did not measure microorganisms, VOC or airborne particles in the classrooms and that data on the home environment was assessed by the questionnaire, only. Another weakness is the lack of nasal physiological data. However, the ISAAC questions on rhinitis and rhinoconjunctivitis have been validated against doctors diagnosis and the agreement was sufficiently good (Vanna et al. 2011; Kim et al. 2012). Another limitation is that the data on IgE-mediated allergy is questionnaire data. However, high specificity (89–97%) but poorer sensitivity (28–55%) for questionnaire data on allergies have been reported, when allergy testing was the gold standard (Wieslander et al. 1997; Lakwijk et al. 1998; Linneberg et al. 2001). Thus, students reporting allergies could be expected to be sensitized. However, because of the lower sensitivity, the true prevalence of allergic sensitization could be underestimated, especially since we had no information on house dust mite allergy. Moreover, as cross-sectional study measure associations, such studies cannot be used to draw conclusions on causality.