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.
- Inhalation Toxicology - INHAL TOXICOL. 01/1995; 7(5):645-655.
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ABSTRACT: The objective of the present study was to assess the prevalence of asthma and asthma-related symptoms in Finland. We also wondered whether chronic cough may be an indicator of occult asthma. Prevalence and characteristics of children with doctor-diagnosed asthma and chronic respiratory symptoms were investigated in 7-12 year old school children from eastern Finland by using a questionnaire on respiratory symptoms. In addition, skin-prick tests, flow-volume spirometry, and serum total immunoglobulin E (IgE) measurements were performed in children reporting chronic respiratory symptoms. The parent-reported prevalence of doctor-diagnosed asthma was 4.4%, of wheezing 5.4%, of attacks of shortness of breath with wheezing 4.6%, and of dry cough at night 12%. Children with dry cough only (n = 195) had less frequent parental asthma, self-reported allergies, daily respiratory medication, and moisture stains or molds at home than asthmatic children (n = 180), but these findings were more frequent than among asymptomatic children (n = 2,169). The prevalence of at least one positive skin-prick test result was 79% among the asthmatic children and 55% among children with dry cough only. There were no differences between the two symptom groups in serum total IgE levels and spirometric lung functions, except in maximal mid-expiratory flow (MMEF) values, which were significantly lower among children with asthmatic symptoms. The present results support the hypothesis that chronic cough may be an indicator of occult asthma. Therefore, to improve the sensitivity of respiratory questionnaires designed to detect asthma, they should also include questions on chronic cough.(ABSTRACT TRUNCATED AT 250 WORDS)European Respiratory Journal 08/1995; 8(7):1155-60. · 6.36 Impact Factor
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ABSTRACT: Several recent studies have reported associations between short term changes in air pollution and respiratory hospital admissions. This relationship was examined in two cities with substantially different levels of sulphur dioxide (SO2) but similar levels of airborne particles in an attempt to separate the effects of the two pollutants. Significant differences in weather between the two cities allowed the evaluation of that potential confounder also. Daily counts of admissions to all hospitals for respiratory disease (ICD 9 460-519) were constructed for persons aged 65 years and older in two cities - New Haven, Connecticut and Tacoma, Washington. Each city was analysed separately. Average daily concentrations of SO2, inhalable particles (PM10), and ozone were computed from all monitors in each city, and daily average temperature and humidity were obtained from the US weather service. Daily respiratory admission counts were regressed on temperature, humidity, day of the week indicators, and air pollution. A 19 day weighted moving regression filter was used to remove all seasonal and subseasonal patterns from the data. Possible U-shaped dependence of admissions on temperature was dealt with using indicator variables for eight categories each of temperature and humidity. Each pollutant was first examined individually and then multiple pollutant models were fitted. All three pollutants were associated with respiratory hospital admissions of the elderly. The PM10 associations were little changed by control for either ozone or SO2. The ozone association was likewise independent of the other pollutants. The SO2 association was substantially attenuated by control for ozone in both cities, and by control for PM10 in Tacoma. The magnitude of the effect was small (relative risk 1.06 in New Haven and 1.10 in Tacoma for a 50 micrograms/m3 increase in PM10, for example) but, given the ubiquitous exposure, this has some public health significance. Air pollution concentrations within current guidelines were associated with increased respiratory hospital admissions of the elderly. The strongest evidence for an independent association was for PM10, followed by ozone. These results are consistent with other studies and suggest that lowering air pollution concentrations would have some impact on public health.Thorax 06/1995; 50(5):531-8. · 8.38 Impact Factor