Effects of ultrafine and fine particles in urban air on peak expiratory flow among children with asthmatic symptoms.
ABSTRACT It has been suggested that ultrafine particles in urban air may cause the health effects associated with thoracic particles (PM10). We therefore compared the effects of daily variations in particles of different sizes on peak expiratory flow (PEF) during a 57-day follow-up of 39 asthmatic children aged 7-12 years. The main source of particulate air pollution in the area was traffic. In addition to the measurements of PM10 and black smoke (BS) concentrations, an electric aerosol spectrometer was used to measure particle number concentrations in six size classes ranging from 0.01 to 10.0 microns. Daily variations in BS and particle number concentrations in size ranges between 0.032 and 0.32 micron and between 1.0 and 10.0 microns were highly intercorrelated (correlation coefficients about 0.9). Correlations with PM10 were somewhat lower (below 0.7). All these pollutants tended also to be associated with declines in morning PEF. However, the only statistically significant associations were observed with PM10 and BS. Different time lags of PM10 were also most consistently associated with declines in PEF. Therefore, in the present study on asthmatic children, the concentration of ultrafine particles was no more strongly associated with variations in PEF than PM10 or BS, as has earlier been suggested.
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ABSTRACT: The relationship between particle number concentration and the established air quality indicators such as PM10 and NO2 is very important regarding the environmental quality of air. The results of this study revealed that correlation of the number of particles and NO2 depends on the mixing processes in the atmosphere, such as the formation of boundary layer and mixing layer. The diurnal variation of the correlation of the number of particles and PM10 is related to their sources and life times in an urban atmosphere. The effect of the wind speed and rainfall is strong in the correlation of NO2 and number of particles.Procedia Environmental Sciences. 01/2011; 6:60–69.
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ABSTRACT: This paper reports the size classification of nanoparticles as well as electrical tuning techniques for the cut-off diameter and collection efficiency. Classifying particles < 100 nm in diameter is quite a technical challenge using a virtual impactor with the cut-off diameter being determined geometrically. However, the proposed virtual impactor can classify particlesJournal of the Korean Society for Precision Engineering. 01/2009; 26(2).
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ABSTRACT: Objectives Increased air pollutant concentrations have been linked to several asthma-related outcomes in children, including respiratory symptoms, medication use, and hospital visits. However, few studies have examined effects of ultrafine particles in a pediatric population. Our primary objective was to examine the effects of ambient concentrations of ultrafine particles on asthma exacerbation among urban children and determine whether consistent treatment with inhaled corticosteroids could attenuate these effects. We also explored the relationship between asthma exacerbation and ambient concentrations of accumulation mode particles, fine particles (≤2.5 micrograms [μm]; PM2.5), carbon monoxide, sulfur dioxide, and ozone. We hypothesized that increased 1–7 day concentrations of ultrafine particles and other pollutants would be associated with increases in the relative odds of an asthma exacerbation, but that this increase in risk would be attenuated among children receiving school-based corticosteroid therapy. Methods We conducted a pilot study using data from 3 to 10 year-old children participating in the School-Based Asthma Therapy trial. Using a time-stratified case-crossover design and conditional logistic regression, we estimated the relative odds of a pediatric asthma visit treated with prednisone (n=96 visits among 74 children) associated with increased pollutant concentrations in the previous 7 days. We re-ran these analyses separately for children receiving medications through the school-based intervention and children in a usual care control group. Results Interquartile range increases in ultrafine particles and carbon monoxide concentrations in the previous 7 days were associated with increases in the relative odds of a pediatric asthma visit, with the largest increases observed for 4-day mean ultrafine particles (interquartile range=2088 p/cm3; OR=1.27; 95% CI=0.90–1.79) and 7-day mean carbon monoxide (interquartile range=0.17 ppm; OR=1.63; 95% CI=1.03–2.59). Relative odds estimates were larger among children receiving school-based inhaled corticosteroid treatment. We observed no such associations with accumulation mode particles, black carbon, fine particles (≤2.5 μm), or sulfur dioxide. Ozone concentrations were inversely associated with the relative odds of a pediatric asthma visit. Conclusions These findings suggest a response to markers of traffic pollution among urban asthmatic children. Effects were strongest among children receiving preventive medications through school, suggesting that this group of children was particularly sensitive to environmental triggers. Medication adherence alone may be insufficient to protect the most vulnerable from environmental asthma triggers. However, further research is necessary to confirm this finding.Environmental Research 02/2014; 129:11–19. · 3.24 Impact Factor