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Ozone (O3) is a pollutant of concern in urban areas because of its effects on health, crops, ecosystems, and materials. Despite efforts to meet the Japanese air quality standard for O3 in the Kanto region, the attainment percentage is close to zero. Considering that O3 formation is sensitive to emissions of volatile organic compounds (VOC) and nitrogen oxides (NOx), this study evaluated a range of reductions in the emissions of both precursors using a regional air quality model (ADMER-PRO) and estimated their benefits measured as the economic change due to O3 concentration differences between scenarios. The simulation period was set during the 2016 O3 season. The results showed that O3 concentrations could be reduced using two approaches: significant reduction in VOC levels combined with minor NOx level changes or significant NOx emission reduction. Significant reduction in NOx levels was the most effective strategy for a generalized decrease in the O3 levels in the Kanto region, and the benefit analysis revealed that the most significant economic impacts could be achieved by adopting the latter approach. [ABSTRACT FROM AUTHOR]

We have investigated the pressure dependence of the detection sensitivity of CO2, N2O and CH4 using wavelength modulation spectroscopy (WMS) with distributed feed-back diode lasers in the near infrared region. The spectral line shapes and the background noise of the second harmonics (2f) detection of the WMS were analyzed theoretically. We determined the optimum pressure conditions in the detection of CO2, N2O and CH4, by taking into consideration the background noise in the WMS. At the optimum total pressure for the detection of CO2, N2O and CH4, the limits of detection in the present system were determined. [ABSTRACT FROM AUTHOR]

We have investigated the pressure dependence of the detection sensitivity of CO2, N2O and CH4 using wavelength modulation spectroscopy (WMS) with distributed feed-back diode lasers in the near infrared region. The spectral line shapes and the background noise of the second harmonics (2f) detection of the WMS were analyzed theoretically. We determined the optimum pressure conditions in the detection of CO2, N2O and CH4, by taking into consideration the background noise in the WMS. At the optimum total pressure for the detection of CO2, N2O and CH4, the limits of detection in the present system were determined. [ABSTRACT FROM AUTHOR]

This study evaluated gasoline evaporative emissions from fuel-cap removal during the refueling process (or "puff loss") for one gasoline vehicle in the Japanese market. Specifically, the puff loss emissions were measured after a real-world driving event in urban Tokyo, Japan for different seasons and gasoline types. The experimental results indicated higher puff loss emissions during summer than in winter and spring despite using low vapor pressure gasoline during summer. These higher puff loss emissions accounted maximally for more than 4 g of the emissions from the tested vehicle. The irregular emission trends could be attributed to the complex relationships between physical parameters such as fuel-tank filling, ambient temperature, ambient pressure, and gasoline vapor pressure. Furthermore, an estimation model was developed based on the theory of thermodynamics to determine puff loss emissions under arbitrary environmental conditions. The estimation model included no fitting parameter and was in good agreement with the measured puff loss emissions. Finally, a sensitivity analysis was conducted to elucidate the effects of three physical parameters, i.e., fuel tank-filling, ambient pressure, and gasoline type, on puff loss emissions. The results indicated that fuel tank-filling was the most important parameter affecting the quantity of puff loss emissions. Further, the proposed puff loss estimation model is likely to aid the evaluation of future volatile organic compound emission inventories. [ABSTRACT FROM AUTHOR]