Background Asthma prevalence varies widely among neighborhoods within New York City. Exposure to mouse and cockroach allergens has been suggested as a cause. Objective To test the hypotheses that children living in high asthma prevalence neighborhoods (HAPN) would have higher concentrations of cockroach and mouse allergens in their homes than children in low asthma prevalence neighborhoods (LAPN), and that these exposures would be related to sensitization and asthma. Methods In the NYC Neighborhood Asthma and Allergy Study, a case-control study of asthma, 7–8 year old children from HAPN (n=120) and LAPN (n=119) were recruited through the same middle-income health insurance plan. Children were classified as asthma cases (n=128) or non-asthma controls (n=111) based on reported symptoms or medication use. Allergens were measured in bed dust. Results HAPN homes had higher Bla g 2 (P=0.001), Mus m 1 (P=0.003) and Fel d 1 (P=0.003) and lower Der f 1 (P=0.001) than LAPN homes. Sensitization to indoor allergens was associated with asthma, but relevant allergens differed between LAPN and HAPN. Sensitization to cockroach was more common among HAPN than LAPN children (23.7% vs. 10.8%, P=0.011). Increasing allergen exposure was associated with increased probability of sensitization (IgE) to cockroach (P<0.001), dust mite (P=0.009) and cat (P=0.001), but not mouse (P=0.58) or dog (P=0.85). Conclusions These findings further demonstrate the relevance of exposure and sensitization to cockroach and mouse in an urban community and suggest that cockroach allergen exposure could contribute to the higher asthma prevalence observed in some compared with other NYC neighborhoods.

Increased heat-related morbidity and mortality are expected direct consequences of global warming. In the developed world, most fatal heat exposures occur in the indoor home environment, yet little is known of the correspondence between outdoor and indoor heat. Here we show how summertime indoor heat and humidity measurements from 285 low- and middle-income New York City homes vary as a function of concurrent local outdoor conditions. Indoor temperatures and heat index levels were both found to have strong positive linear associations with their outdoor counterparts; however, among the sampled homes a broad range of indoor conditions manifested for the same outdoor conditions. Using these models, we simulated indoor conditions for two extreme events: the 10-day 2006 NYC heat wave and a 9-day event analogous to the more extreme 2003 Paris heat wave. These simulations indicate that many homes in New York City would experience dangerously high indoor heat index levels during extreme heat events. These findings also suggest that increasing numbers of NYC low- and middle-income households will be exposed to heat index conditions above important thresholds should the severity of heat waves increase with global climate change. The study highlights the urgent need for improved indoor temperature and humidity management.

Differential exposure to combustion by-products and allergens may partially explain the marked disparity in asthma prevalence (3%–18%) among New York City neighborhoods. Subclinical changes in airway inflammation can be measured by fractional exhaled nitric oxide (FeNO). FeNO could be used to test independent effects of these environmental exposures on airway inflammation. Seven and eight year-old children from neighborhoods with lower (range 3–9%, n=119) and higher (range 11–18%, n=121) asthma prevalence participated in an asthma case-control study. During home visits, FeNO was measured, and samples of bed dust (allergens) and air (black carbon) were collected. Neighborhood built-environment characteristics were assessed for the 500m surrounding participants’ homes. Airborne black carbon concentrations in homes correlated with neighborhood asthma prevalence (P<0.001) and neighborhood densities of truck routes (P<0.001) and buildings burning residual oil (P<0.001). FeNO concentrations were higher among asthmatics with compared to asthmatics without frequent wheeze (≥4 times/year) (P=0.002). FeNO concentrations correlated with domestic black carbon among children without seroatopy (P=0.012) and with dust mite allergen among children with seroatopy (P=0.020). The association between airborne black carbon in homes and both neighborhood asthma prevalence and FeNO suggest that further public health interventions on truck emissions standards and residual oil use are warranted.

Background-Numerous mechanisms link outdoor weather and climate conditions to human health. It is likely that many health conditions are more directly affected by indoor rather than outdoor conditions. Yet, the relationship between indoor temperature and humidity conditions to outdoor variability, and the heterogeneity of the relationship among different indoor environments are largely unknown.Methods-We use 5-14 day measures of indoor temperature and relative humidity from 327 dwellings in New York City for the years 2008-2011 to investigate the relationship between indoor climate, outdoor meteorological conditions, socioeconomic conditions, and building descriptors. Study households were primarily middle-income and located across the boroughs of Brooklyn, Queens, Bronx, and Manhattan.Results-Indoor temperatures are positively associated with outdoor temperature during the warm season and study dwellings in higher socioeconomic status neighborhoods are significantly cooler. During the cool season, outdoor temperatures have little effect on indoor temperatures; however, indoor temperatures can range more than 10 °C between dwellings despite similar outdoor temperatures. Apartment buildings tend to be significantly warmer than houses and dwellings on higher floors are also significantly warmer than dwellings on lower floors. Outdoor specific humidity is positively associated with indoor specific and relative humidity, but there is no consistent relationship between outdoor and indoor relative humidity. Conclusions-InNew York City, the relationship between indoor and outdoor temperature and humidity conditions vary significantly between dwellings. These results can be used to inform studies of health outcomes for which temperature or humidity is an established factor affecting human health and highlights the need for more research on the determinants of indoor climate.