Ozone is a secondary air pollutant produced from photochemical air pollutants such as NOx and non-methane hydrocarbons (NMHC). It can not only cause adverse respiratory effects for humans but also damage plants and metalic meterials. Taiwan EPA (Environmental Protection Administration) air quality data show that ozone concentration has increased in recent years. The PSI data of 2000-2004 in Mid-Taiwan showed that ozone played an increased important role in local air quality, especially in Nantou county. Furthermore, the Nantou government has continuously developed tours business to boost the local economy. As a result, the traffic has increased in the country and air quality has become worse. This study investigated the variations of ozone concentration in Nantou county.
Previous ozone studies in Taiwan used the EPA air-quality monitor data only for the ground levels. This study assessed the ozone distributions in the atmospheric environment including both ground level monitoring data and vertical sampling data. Using the tethered balloon technique, ozone sampling was collected using liquid passive samplers (LiPS) installed at different height above the ground level. Ozone concentrations in the air samples collected at different altitudes were determined after controlling the weather parameters including pressure, vertical temperature, relative humidity, wind direction and wind speed through the meteorological sounding system at Chi-Chi mountain, a discrete mountain remote from other hills, in Nantou. The ozone concentrations related to traffic influence both in the weekdays and weekends were the focus of this study.
Results of LiPS data showed that the ozone concentrations varied by the vertical altitudes in this Nantou Mountain. Two major findings included: First, the ozone concentration was the highest at the altitude of 1200-1400 meter during the sampling period, with the ozone concentrations on weekdays of greater than 60ppb on weekends, and greater than 40ppb on weekdays. Second, there was lowly correlation between the ozone concentration and the absolute humidity.
Based on the previous studies, the traffic density is heavier on the weekends than on weekdays in Nantou county. The local traffic density is an explanation parallel to the higher ozone concentration observed in Nantou on weekends. However the occurs of temperature inversion also had a significant effect on ozone concentrations appeared from the assessment of both ground level and vertical dimensions.
