Domestic airborne black carbon and exhaled nitric oxide in children in NYC

Abstract

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; BC) were collected. Neighborhood built-environment characteristics were assessed for the 500 m surrounding participants' homes. Airborne BC 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 than in those without frequent wheeze (≥4 times/year) (P=0.002). FeNO concentrations correlated with domestic BC among children without seroatopy (P=0.012) and with dust mite allergen among children with seroatopy (P=0.020). The association between airborne BC 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.

Figure 1. Schematic illustrating the use of FeNO as a biomarker of airway inflammation to model risk for asthma exacerbation with environmental exposures

Figure 2. Predictors of domestic airborne BC

There was a significant correlation between BC and a) neighborhood asthma prevalence (R=0.33, P<0.001), B) density of buildings burning residual oil (R=0.37, P<0.001) and C) density of truck routes (R=0.31, P<0.001). Lines represent linear regression with 95% CI in gray. Points are color coded by homes in low (blue) and high (red) asthma prevalence neighborhoods

Figure 3. Correlation between FeNO and BC among non-seroatopic (A, P=0.009) and seroatopic (B, P=0.083) children and dust mite allergen among non-seroatopic (C, P=0.68) and seroatopic (D, P=0.029) children

Lines represent linear regression 95% CI (gray). Points are color coded to represent children living in low (blue) and high (red) asthma prevalence neighborhoods.