This study examined the carbon dioxide (CO_2) pollution inside vehicles under low ventilation condition and evaluated the Air Quality System (AQS) for in-vehicle air quality using two techniques. The low ventilation condition is not recommended in order to keep oxygen-rich condition inside vehicles. Under the low ventilation condition, the in-vehicle CO_2 concentrations exceeded 1,000 ppm, the air quality guidelines in the United States, Western Europe, and Japan, indicating more oxygen deficiency inside vehicles. On the contrary, with the AQS-on condition, the in-vehicle CO_2 concentrations were less than 1,000 ppm for most of the driving time, indicating that the AQS could solve the problem of CO_2 accumulation inside vehicles under the low ventilation condition. The AQS test conducted by comparing carbon monoxide (CO) and volatile organic compound (VOC) concentrations inside two vehicles indicated that the AQS effectively decreased the in-vehicle concentrations by 21 to 36%, as compared to medium ventilation condition with the windows closed, the vent opened, and air conditioning on. In addition, The AQS test conducted by comparing the interior and exterior concentrations indicated that the AQS effectively decreased the in-vehicle concentrations by 18 to 31%, as compared to medium ventilation condition.

Recently, bathes have been suspected to an important source of indoor exposure to volatile organic compounds(VOCs). Two experiments were conducted to evaluate chloroform exposure and corresponding body burden by exposure routes while bathing. Another experiment was conducted to examine the chloroform dose during dermal exposure and the chloroform decay in breath after dermal exposure. The chloroform dose was determined based on exhaled breath analysis. The exhaled breath concentration measured after normal baths (2.8 ㎍/㎥) was approximately 13 times higher that measured prior to normal bathes (0.2 ㎍/㎥). Based on the means of the normalized post exposure chloroform breath concentration, the dermal exposure was estimated to contribute to 74% of total chloroform body burden while bathing. The internal dose from bathing (inhalation plus dermal) was comparable to the dose estimated from daily water ingestion. The risk associated with a weekly, 30-min bath was estimated to be 1 x 10^-5, while the risk from daily ingestion of tap water was to be 0.5 × 10^-5 for 0.15 1 and 6.5 × 10^-5 for 2.0 1. Chloroform breath concentration increased gradually during the 60 minute dermal exposure. The breath decay after the dermal exposure showed two-phase mechanism, with early rapid decay and the second slow decay. The mathematical model was developed to describe the relationship between water and air chloroform concentrations, with R^2 = 0.4 and p<0.02.

Vehicle occupant exposure to volatile organic compounds (VOCs) has been a subject of concern in recent years because of higher levels of VOCs inside vehicles as compared to the surrounding ambient atmosphere and because of the toxicity of VOCs. The effectiveness of two commercial ACDs for the removal of selected VOCs in the interior of automobiles was evaluated on 115 commutes through urban (Taegu) commutes by two cars and 9 idles. The idling and commuting studies conducted under four different driving conditions showed that the two commercial ACDs were not effective for the removal of VOCs in the interior of vehicles. The concentrations of all target VOCs except benzene were significantly higher (p<0.05) in the interior of older car than of newer car. The mean levels of benzene and toluene measured in this study were well excess of earlier other studies in the United States, besides Los Angeles with which was comparable. It was reported that the in-vehicle exposure to benzene and corresponding upper-bound cancer risk were about 8 times higher than those for outdoor environment, while they were about half of those from indoor environment.

The pyrolysis reactions of atomic hydrogen with chloroform were studied in a 4 cm i.d, tubular flow reactor with low flow velocity (518 ㎝/sec) and a 2.6 ㎝ i.d. tubular flow reactor with high flow velocity (1227 ㎝/sec). The hydrogen atom concentration was measured by chemiluminescence titration with nitrogen dioxide, and the chloroform concentrations were determined using a gas chromatography. The chloroform conversion efficiency depended on both the chloroform flow rate and linear flow velocity, but did not depend on the flow rate of hydrogen atom. A computer model was employed to estimate a rate constant for the initial reaction of atomic hydrogen with chloroform. The model consisted of a scheme for chloroform-hydrogen atom reaction, Runge-Kutta 4th-order method for integration of first-order differential equations describing the time dependence of the concentrations of various chemical species, and Rosenbrock method for optimization to match model and experimental results. The scheme for chloroform-hydrogen atom reaction included 22 elementary reactions. The rate constant estimated using the data obtained from the 2.6 cm i.d. reactor was to be 8.1 × 10 exp (-14) ㎤/molecule-sec and 3.8 × 10 exp (-15) ㎤/molecule-sec, and the deviations of computer model from experimental results were 9% and 12%, for the each reaction time of 0.028 sec and 0.072 sec, respectively.

Two experiments were conducted to evaluate breathing zone air quality in Taegu, using automatic analyzers for four air quality standards(SO2, NO2, CO, and O3). First, air target compounds were measured for 8 to 12 hours in each of two commercial areas and five residential areas. Second, air target compounds were hourly measured for 24 hours in each of two commercial areas, two residential areas, and an industrial complex area. Based on the first experiment the breathing zone air was more polluted in the commercial area as compared to the residential area, while the second experiment showed that the breathing zone air was polluted rather in the residential area as compared to the commercial area. The second experiment also indicated that there was some variation of breathing zone air concentration with time and measuring sites. Diurnal variation of breathing zone air concentrations was consistent with previous studies which measured at building height. The highest breathing zone air concentration was shown in Seongseo industrial complex area. An unusual finding of this study was that SO2 concentration in the breathing zone air of Bisandong, a typical residential area of Taegu, was higher than that of other residential areas, even higher than that of Seongseo industrial complex area.