The Sixteenth Conference of the International Society for Environmental Epidemiology (ISEE): Abstracts
As information about the health risks associated with air pollution has become available, attention has focused increasingly on smaller air particles such as particulate matter with an aerodynamic diameter to or less than a 10 or 2.5 u (PM10 or PM2.5, respectively). A number of recent studies conducted in Asia, Europe and the United States have shown that acute exposure to current levels of air particles is associated with adverse health status, including mortality, hospital admissions due to asthma, severity of preexisting chronic illness, low birth weight and pulmonary functions. Our objective was to evaluate the acute effects of ambient air particles on pulmonary function.
This study was directed at the schoolchildren (3th and 6th grades) surrounding the industrial complex of Ulsan, Korea. Each child was provided with a mini-Wright peak flow meter and a preformatted health symptom diary for 4 weeks, and was trained on their proper use. Participants were instructed to perform the peak flow test three times in the standing position, three times daily (9 am, 12 pm, and 8 pm), and to record all the readings along with the symptoms (cold, cough, and asthmatic symptoms) experienced that day. Daily measurement of ambient air particles (PM10 and PM2.5) was obtained on the roof of the participating elementary school building for the same period of this longitudinal study. The relationship between daily PEFR and ambient air particle levels was analyzed using a mixed linear regression models including gender, age in year, height, the presence of respiratory symptoms, and relative humidity as an extraneous variable.
The total number of subjects participating in this longitudinal study was 144. The range of daily measured PEFR in this study was 182∼481 L/min. In general, a PEFR measured in the morning was lower than a PEFR measured in the evening (or afternoon) on the same day. The daily mean concentrations of PM10 and PM2.5 over the study period were 64.9 ug/m3 and 46.1 ug/m3, respectively. The IQR (inter-quartile range) of PM10 and PM2.5 were 50.1 ug/m3 and 23.1 ug/m3. During the study period, the national ambient air quality standard of 150 ug/m3 was exceeded once. The analysis showed that an increase of 1 ug/m3 of PM10 corresponded to 0.45 ug/m3 increment of PM2.5. Daily mean PEFR was regressed with the 24-hour average PM10 (or PM2.5) levels, weather information such as relative humidity, and individual characteristics including gender, age, height, and respiratory symptoms. The analysis showed that the increase of air particle concentrations was negatively associated with the variability in PEFR. We estimated that the IQR increment of PM10 or PM2.5 were associated with 1.5 L/min (95% Confidence intervals −3.1, 0.1) and 0.8 L/min (95% CI −1.8, 0.1) decline in PEFR.
Our objective was to evaluate the relationship between ambient air particles and lung function measured by peak expiratory flow rate (PEFR) among school children. We conducted a community-based diary study and used a classic design for the respiratory effects of ambient air particles and used longitudinal information for one month of follow-up starting from May 15, 2001 to June 12, 2001. The relationship between daily PEFR and ambient air particle levels was analyzed using a mixed linear regression models including gender, age in year, height, the presence of respiratory symptoms, and relative humidity as an extraneous variable. In conclusion, we did not find a significant association between outdoor levels of particulate matter and PEFR. Even though this study shows negative findings on the relationship between respiratory function and air particles, it is worth noting that the findings must be interpreted cautiously because exposure measurement based on monitoring of ambient air likely results in misclassification of true exposure levels and this is the first Korean study that PM2.5 measurement is applied as an index of air particle quality.