In the Cincinnati study into Childhood Allergy and Air Pollution, 624 babies and toddlers of allergic parents were assessed and when exposured to a combination of high levels of indoor allergens (such as bacteria from throat infections, house dust mites and mould spores) plus traffic air pollution, this increased their risk of developing wheezing and persistent asthma by six fold. The well-established Hygiene Hypothesis highlights the connection between a sterile home environment in infancy and the risk of deveoping childhood allergies. It was the combined effect of exposure to high levels of indoor allergens (endotoxin) together with the motor car diesel exhaust fumes that seemed to be such a potent trigger for wheezing and persistent airway inflammation. The resultant chronic airway inflammation is also known to retard long-term normal lung development. While in children exposed to moderate levels of indoor or outdoor allergens, only 11 percent developed asthma and in those exposed to low levels of allergen but high level air pollution, 18 percent developed persistent or chronic asthma.
Posts Tagged ‘hygiene hypothesis’
Motor traffic air pollution increases allergies
Thursday, December 10th, 2009Home hygiene, infections and allergies
Thursday, November 12th, 2009A recent study on children attending day care or nurseries by de Jongste in the American Thoracic Society journal cast some doubt on the so-called Hygiene Hypothesis for allergy development. The Hygiene Hypothesis notion that farm animal faeces exposure and childhood infections will prevent allergies has been promoted for decades. The hygiene hypothesis essentially links a more clean and sterile home environment with the overall rise in allergies seen in many developed Western counties. Poor living conditions with early exposure to germs, infections and parasites seem to shift the infant’s immune system into survival mode (TH1) and away from allergy mode (TH2) when allergy testing. However this immune switching probably occurs very early in the first few months of life. Therefore as mentioned in the American study, day care centre exposure and subsequent childhood infections may have little impact on allergy development. Particularly if the child attends a day-centre after one year of age when their immune type reactivity is more established. It still seems likely that a germ-filled household with difficult living conditions and plenty of sickly older siblings will be more protective from allergies while a sterile, insular environment in early infancy seems to promote allergies.
