IGHE and asthma: Similarly, in the New York City Neighborhood Asthma and Allergy Study (NAAS), Chew et al. found that increased allergen exposure was associated with increased probability of sensitization (IgE) to cockroach (P < 0.001) [36], and cockroach allergen (Bla g2) was more prevalent in the bed dust taken from the homes in the high asthma prevalence neighborhoods (HAPNs) compared with low asthma prevalence neighborhoods (LAPN), while sensitivity to cockroach allergen was twice as common at 23% versus 10% [7].