The effects of urban green space and road proximity to indoor traffic-related PM2.5, NO2, and BC exposure in inner-city schools.

BACKGROUND: Since there are known adverse health impacts of traffic-related air pollution, while at the same time there are potential health benefits from greenness, it is important to examine more closely the impacts of these factors on indoor air quality in urban schools. OBJECTIVE: This study investigates the association of road proximity and urban greenness to indoor traffic-related fine particulate matter (PM2.5), nitrogen dioxide (NO2), and black carbon (BC) in inner-city schools. METHODS: PM2.5, NO2, and BC were measured indoors at 74 schools and outdoors at a central urban over a 10-year period. Seasonal urban greenness was estimated using the Normalized Difference Vegetation Index (NDVI) with 270 and 1230 m buffers. The associations between indoor traffic-related air pollution and road proximity and greenness were investigated with mixed-effects models. RESULTS: The analysis showed linear decays of indoor traffic-related PM2.5, NO2, and BC by 60%, 35%, and 22%, respectively for schools located at a greater distance from major roads. The results further showed that surrounding school greenness at 270 m buffer was significantly associated (p < 0.05) with lower indoor traffic-related PM2.5: -0.068 (95% CI: -0.124, -0.013), NO2: -0.139 (95% CI: -0.185, -0.092), and BC: -0.060 (95% CI: -0.115, -0.005). These associations were stronger for surrounding greenness at a greater distance from the schools (buffer 1230 m) PM2.5: -0.101 (95% CI: -0.156, -0.046) NO2: -0.122 (95% CI: -0.169, -0.075) BC: -0.080 (95% CI: -0.136, -0.026). These inverse associations were stronger after fully adjusting for regional pollution and meteorological conditions. IMPACT STATEMENT: More than 90% of children under the age of 15 worldwide are exposed to elevated air pollution levels exceeding the WHO's guidelines. The study investigates the impact that urban infrastructure and greenness, in particular green areas and road proximity, have on indoor exposures to traffic-related PM2.5, NO2, and BC in inner-city schools. By examining a 10-year period the study provides insights for air quality management, into how road proximity and greenness at different buffers from the school locations can affect indoor exposure.

Question 3: Can we diagnose asthma in children under the age of 5 years?

The diagnosis of asthma in children under five years has been controversial due to changing concepts of what true asthma is in this age group. Previous diagnostic algorithms that used clinical indices to predict the persistence of asthma symptoms or phenotypes based on asthma triggers do not predict which children will benefit from asthma medication. A pragmatic approach to asthma diagnosis in this age group is based on identifying signs and symptoms of reversible airflow obstruction and documenting their response to asthma medication. Hopefully, this approach will provide clearer guidance to clinicians and improve asthma morbidity in these young children.

ß-2 adrenergic receptor gene methylation is associated with decreased asthma severity in inner-city schoolchildren: asthma and rhinitis.

BACKGROUND: Genetic variation in the ß-2 adrenergic receptor gene (ADRB2) has been implicated in asthma severity and control with conflicting results. Epigenetic variation in the ADRB2 may play an important role in asthma phenotype. OBJECTIVE: We aimed to evaluate whether DNA methylation of ADRB2 is associated with asthma phenotypes in inner-city school-aged children. METHODS: Multiple CpG sites in the promoter region of ADRB2 gene were analysed in 177 children enrolled in the School Inner-City Asthma Study. Blood- or saliva-derived DNA was measured by bisulphite-polymerase chain reaction pyrosequencing assay. Average percentage DNA methylation across the sites was evaluated for association with asthma severity (report of dyspnoea, night-time symptoms, rescue medication use, and baseline spirometry) and morbidity (school absences and unscheduled healthcare visits). Three clades composed of highly correlated methylation sites within the methylated segment of ADRB2 were further analysed. RESULTS: Methylation of individual sites generally ranged from 0% to 6% with average percentage methylation across sites of 2.4%. Univariate analyses strongly favoured the association of higher percentage methylation with lower asthma severity measured by report of dyspnoea. Furthermore, there was a non-significant trend towards less rescue medication use, night-time symptoms, school absences, activity limitation due to asthma, and improved lung function measurements with increased methylation. Multivariate analysis demonstrated methylation of ADRB2 gene significantly associated with less dyspnoea (odds ratio (OR) 0.2, 95% confidence interval (CI), 0.1-0.6, P = 0.002). Each of the three clades of methylation sites showed a strong, but not statistically significant, effect on decreased dyspnoea. CONCLUSIONS AND CLINICAL RELEVANCE: DNA methylation in the ADRB2 gene is associated with decreased asthma symptom severity, suggesting a role for methylation in asthma phenotypes.