The association of dust events with asthma exacerbation in the U.S.-Mexico border children: A pilot study
Background. Asthma is one of the most prevalent chronic pediatric illnesses in the U.S. and a major cause of childhood disability, hospitalization, and missed schooldays. Air pollution is one of a number of known environmental triggers known to exacerbate pediatric asthma. Emerging evidence also suggests that exposure to dust aerosols associated with dust storm events may trigger asthmatic symptoms. The Paso del Norte (PDN) region is the single most dust-prone major metropolitan area in the U.S., averaging 14.5 major dust events/yr. The annual peak in dust event activity occurs during March to May where there is a 42% chance of blowing dust on any day. Pediatric asthma is common in the PDN. Published and unpublished studies estimate asthma prevalence in El Paso children at 5-15%. In Ciudad Juarez, the prevalence of medically diagnosed asthma has been estimated at 6.8% and wheezing at 20%. Objectives and hypotheses. A panel pilot study was conducted to explore the association between dust aerosol exposure and symptom exacerbation in asthmatic El Paso children. It was hypothesized that exposure to high ambient PM concentrations produced during dust events (especially finer particulates in the < 2.5-0.09 nm diameter range) will be associated with symptom exacerbation in asthmatic children because of ability of particles in this size range to readily penetrate to lower airways where they initiate the Type 2 immune response inflammatory process. Methods. Medically diagnosed asthmatic children were identified from the original UTEP ARCH Cohort study and recruited for participation. The inclusion criteria were age 5-17 years, medically diagnosed asthma, current asthma sufferer, and El Paso area resident. Subjects and their parents/guardians who elected to participate went through the informed consent & assent process (UTEP IRB #94578-2). Detailed dust aerosol data (size and elemental composition) were collected over a consecutive 42 day period (April 1-May 15, 2009) by the ARCH companion project using an 8-Stage DRUM sampler. Sampling was performed by upwind-downwind transect in four geographical sites. Additional data on PM2.5 and PM10 concentrations were obtained from TECQ central air monitors. Subjects/parents used a 16-question asthma diary (Juniper et al., 2000) to record daily symptoms during the 42-day study period (e.g., wheezing, persistent cough, chest tightness, shortness of breath, activity limitations, asthma medications, asthma-related outpatient visits/hospitalizations). Three unannounced telephone calls to verify the previous day’s diary entries were made to each home over the 5.5-week study period as a quality control check. Results. The 24 study participants ranged in age from 7-17 years (x=11.8 ± 3.0 yrs). The majority were female (58.3%), Hispanic (83.3%), and had lived in El Paso since birth (91.7%). During the study period, recorded 24-hour average of PM2.5 that ranged from 5 ± 1.9 μg/m 3 to 16 ± 9.1 μg/m3 while that of PM 10 ranged from 16 ± 5.6 μg/m3 to 92 ± 77.2 μg/m3. The concentration of elements such as silicion, sulfur, and lead was elevated on high dust days. On the high compared to low PM2.5 days, there was a statistically significant increase in the proportion of the asthmatic subjects who experienced moderate-severe shortness of breath, wheezing, and chest pain. A statistically significant increase also was identified regarding the proportion of children reporting moderate-severe chest pain and persistent coughing during the high compared to low PM 10 days. In addition, the number of children who experienced moderate-severe limitations in their overall daily activities and who received emergency medical treatment for their asthma was significantly increased on high compared to low PM10 days. Conclusions. The preliminary evidence from this pilot study suggests that exposure to high PM10 as well as PM2.5 from dust, fire and other sources may exacerbate pediatric asthma. However, future studies are needed which employ a larger sample size and a longer observation period in order to improve statistical contrast of maximal and minimal dust aerosol periods for the data analyses.
Gaytan, Monika, "The association of dust events with asthma exacerbation in the U.S.-Mexico border children: A pilot study" (2009). ETD Collection for University of Texas, El Paso. AAI1473863.