Estimating the exposure and dose of children with asthma to air pollutants in an urban industrialized area

Abstract

Asthma affects millions of people worldwide and there is substantial evidence that air pollution exposure is associated with asthma prevalence. For children, the impact is aggravated because their lungs are developing; they have higher ventilation rates and tend to be engaged in daily physical activities. All this contributes to higher doses (also per body weight) than adults have in the same exposed environment. In the Metropolitan Region of Vitoria (MRV), previous epidemiological assessments showed that asthma prevalence among children is higher than the national average. Furthermore, pollutants such as PM2.5 and SO2 impose different associated risks of respiratory symptoms. Nevertheless, to this day no study in MRV approached the exposure and dose of air pollutants at the individual level. Thus, in this work the author aims to address this gap in corroboration with the ongoing project ‘ASMAVIX’. This study follows twenty-one children from three different neighborhoods (thus three campaigns) in their daily activities. To establish the methodology for exposure assessment a systematic review is proposed. The author observes drawbacks in 104 papers and approaches children exposure using the best practices found. The literature review also provides a list of opportunities, challenges, and recommendations for future studies to estimate exposure and the associations between air pollutants and asthma prevalence. In the concentration assessment of particles (PM10 and PM2.5) and gaseous pollutants (NOx, NO2, and SO2) at children’s home, school and pathway, the author uses the dispersion model CALPUFF, alongside with outdoor monitoring and personal samplers; all integrated with routine aspects of participants. PM10 and PM2.5 indoor-outdoor (I/O) ratios are calculated (through indoor measurements) and gases I/O derives from literature. This research results support that the correct choice (or measurement of) indoor-outdoor ratios proved to be of significant importance in a holistic exposure assessment, especially for particulate matter. Pathway exposition showed little significance in this study approach, as revealed by sensitivity tests. The main environmental factors interfering in dosage are proximity to sources, and time spent indoors. Physiological key variables are the body mass index and ventilation minute. Thus, more research on I/O ratios on different environment and inhalation rates of children with asthma would benefit future analysis using the proposed method.