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

Category: Urban Air Quality

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DOI: 10.4209/aaqr.2017.10.0435
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Bich-Thuy Ly 1, Yutaka Matsumi 2, Tomoki Nakayama2,3, Yosuke Sakamoto4,5,6, Yoshizumi Kajii4,5,6, Dung Trung Nghiem1

  • 1 School of Environmental Science and Technology, Hanoi University of Science and Technology, Hanoi, Vietnam
  • 2 Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, Aichi 464-8601, Japan
  • 3 Graduate School of Fisheries and Environmental Sciences, Nagasaki University, Nagasaki, Nagasaki 852-8521, Japan
  • 4 Graduate School of Global Environmental Studies, Kyoto University, Kyoto, Kyoto 606-8501, Japan
  • 5 Graduate School of Human and Environmental Studies, Kyoto, Kyoto 606-8501, Japan
  • 6 Center for Regional Environmental Research, National Institute for Environmental Studies, Tsukuba, Ibaraki 305-8506, Japan

Highlights

Observation of PM2.5 was conducted using high temporal resolution sensors in Hanoi.
Hourly PM2.5 mass concentrations by the sensor agreed with those by a BAM instrument.
PM2.5 levels were high in dry season (winter) and low in rainy season (summer).
PM2.5 haze episodes were observed, especially several days after a cold surge.
This research reveals for first time characteristics of PM2.5 haze episode in Hanoi.


Abstract

A year round observation of concentrations of PM2.5 was conducted in Hanoi from July 2016 to June 2017 using newly developed highly sensitive sensors. 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 in the dry season, particularly in December (median = 62 µg m–3) and low in 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 link to East Asia winter monsoon, because the daily levels of PM2.5 and CO increased several days after most of cold surge events. Two episode events were investigated further in 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 at rush hours. For first event, short peaks of PM2.5 with high rates of increase of ~5 µg m–3 min–1 were observed. This highlights the importance of high temporal resolution of PM2.5 sensors in assessing of health effect. For second event, a broad peak of PM2.5 with gradual increase was observed together with high CO levels. This research reveals characteristics of PM2.5 haze episode in Hanoi that should be studied further to develop an effective air pollution management.

Keywords

PM2.5 measurement compact sensor Mega city Southeast Asia


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