Showing papers by "Yutaka Matsumi published in 2018"

Development and evaluation of a palm-sized optical PM2.5 sensor

Abstract: A new palm-sized optical PM2.5 sensor has been developed and its performance evaluated. The PM2.5 mass concentration was calculated from the distribution of light scattering intensity by considerin...

Characterizing PM2.5 in Hanoi with New High Temporal Resolution Sensor

Abstract: A year-long observation of PM2.5 concentrations was conducted in Hanoi from July 2016 to June 2017 using newly developed highly sensitive sensors. The hourly concentration data of PM2.5 agreed well with corresponding data obtained with a beta attenuation monitor located 3 km away, with R2 = 0.73. The monthly variation showed that levels of PM2.5 were high during the dry season, particularly in December (median = 62 µg m–3) and low during the rainy season, particularly in June and July (medians = 19 µg m–3). Haze episodes of PM2.5 with levels higher than 100 µg m–3 were observed 13 times during the dry season (October 2016–March 2017). These episodes may be linked to the East Asian winter monsoon, as the daily levels of PM2.5 and CO increased several days after most of the cold surge events. Two events were investigated further at a higher temporal resolution. For both events, peaks of PM2.5 appeared at midnight for some days after a cold surge, while CO levels often increased during rush hours. For the first event, brief peaks of PM2.5 with a high rate of increase (~5 µg m–3 min–1) were observed, highlighting the importance of a high temporal resolution for PM2.5 sensors in assessing health effects. For the second event, a broad peak of PM2.5 with a gradual increase was observed along with high CO levels. This research reveals the characteristics of PM2.5 haze episodes in Hanoi, which should be studied further to effectively manage air pollution.

Effect of Oxidation Process on Complex Refractive Index of Secondary Organic Aerosol Generated from Isoprene

Abstract: Oxidation of isoprene by hydroxyl radical (OH), ozone (O3), or nitrate radical (NO3) leads to the formation of secondary organic aerosol (SOA) in the atmosphere This SOA contributes to the radiation balance by scattering and absorbing solar radiation In this study, the effect of oxidation processes on the wavelength-dependent complex refractive index (RI) of SOA generated from isoprene was examined Oxidation conditions did not have a large effect on magnitude and wavelength dependence of the real part of the RI In the case of SOA generated in the presence of sulfur dioxide (SO2), significant light absorption at short visible and ultraviolet wavelengths with the imaginary part of the RI, up to 0011 at 375 nm, was observed during oxidation with OH However, smaller and negligible values were observed during oxidation with O3 and NO3, respectively Moreover, in the absence of SO2, light absorption was not observed regardless of the oxidation process There was an empirical correlation between the imagin

The some results of study on outdoor and indoor ambient PM 2.5

Abstract: In this study, PM2.5 pollution of indoor and outdoor ambience has been measured on a household which is located between the Ger area and the residential district at simultaneous duration and point. In order to analyze, we used n = 3,119,500 data which was measured at each 10 second during 24 hours period. The instrument that was used to study, created by Nagoya University and Panasonic Corporation. In recent years, the capital of Ulaanbaatar, Mongolia, is leading the air pollution during the winter in the world, and the majority of this pollution is comprised of PM2.5 . Fine particles are very harmful to human health, and people spend approximately 90% of their lives in the indoor ambient. Thus, it is important to measure continuously the amount of indoor and outdoor PM2.5, so we have selected two points and indicated some statistical analysis on indoor and outdoor ambient. The results of this study indicate the PM2.5 concentrations of air in Ulaanbaatar are higher than the air quality standard in October and peak in the December and January. Also, due to the feature of the sites being measured, pollution of indoor ambient was demonsrated strong or weak level, which is depended on outdoor ambient pollution. The measurements of the majority days were a high level of pollution from at 00:00 to 04:00 pm, however, it was decreased at 5:00 pm, but it started to increase around 07:00 to 09:00 in the morning, and it decreased from 10:00 am to low level of the pollution whole day. At 18 o’clock in the evening, the pollution was increasing and at the peak of the day, the fine particle pollution up to 02:00 on the next day.

Characterising seasonal variations and spatial distribution of ambient pm2.5 concentration based on short-term monitoring in darkhan city

Abstract: The purpose of this study was to survey the seasonal variation of fine particulate matter (PM2.5) concentration and determine spatial distribution in Darkhan city. Air pollution research and reports have been few and far between in most of parts in Mongolia, especially in Darkhan with respect to quantitative aerosol particle concentration. In this study, we utilized “PM2.5sensor” to measure spatial and seasonal variation of particulate matter concentrations in the study area. The monitoring points were chosen by basing on their specific features and set up directly at ambience outdoor. In each season, we carried out measurement at 3 points, which covered the ger district and apartment district areas for one day. Whereas, at one point the ger district was sampled for 4 days in summer. Fine particulate matter concentrations were the highest in the ger district area because there are many households that use coal for their daily heating and cooking, and at the bared surface. As for seasonal variation, in winter pollution reached 400 times higher than other seasons. Furthermore, at the ger district area, PM2.5 concentration was as much as 20 times greater than other points and it was observed that this too had its impact on the apartment district as well. As regards the air quality index, the level of particulate matter in the ger district area is extremely unhealthy to hazardous in winter. While, good and moderate indexes were mostly identified at monitoring points during the springtime.