Variability in individual ventilation rate and effects on the inhaled dose of traffic-related air pollution (TRAP) and exhaled nitric oxide (eNO) amongst children with asthma

Abstract

TPS 683: Short-term health effects of air pollutants 2, Exhibition Hall, Ground floor, August 28, 2019, 3:00 PM - 4:30 PM Background/Aim: Exposures to TRAP are causally associated with exacerbation of asthma in children, (Health Effects Institute, 2010 annual report). However, exposure assessment in most epidemiological studies relies on data from central-site or personal monitoring without considering personal activity patterns or ventilation rates. Our aims were to estimate the inhaled dose of TRAP using individual-specific, time-activity data and compare the dose-response relationship with central-site and personal exposure in children with asthma. Methods: We recruited 35 school-aged children with asthma in seaport-adjacent communities of Newark, NJ. For up to thirty consecutive days, we ascertained participants’ daily time-activity patterns along with personal exposure to black carbon (BC), a surrogate for TRAP, and eNO, a marker of inflammation. We calculated lag0 (i.e. previous 0-24 hour) and lag2 days (i.e. previous 48-72 hour) inhaled BC doses using ventilation rates based on USEPA reference values and the air pollution exposure (APEX) model based on time-activity data. Mixed-effect models were used to estimate relative risks (RRs) and 95% confidence intervals (95%CIs) of changes in FeNO per interquartile range (IQR) increase in BC exposure. Results: Compared with non-APEX calculation, the mean inhaled dose of BC using APEX model were lower on both lag0 (41.88μg/day vs. 45.62μg/day; P value <0.0001) and lag2 days (42.45μg/day vs. 46.02μg/day; P value <0.0001). High correlations were found between doses calculated with and without using the APEX model on lag0 (r=0.89) and lag2 days (r=0.87). Inhaled BC doses based on either ventilation reference values or the APEX model were not associated with changes in FeNO. Conclusions: The inhaled BC dose estimated using APEX model were lower in both lag periods compared to doses calculated based on reference values. However, associations between inhaled dose and acute changes in FeNO were not observed.