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The abundance of heat-trapping asphalt and concrete, smog, and heat emitted from buildings and vehicles is one of the major reasons for the prevailing high temperature, air and noise pollution in cities. Incorporation of green wall in buildings is considered to be an effective method to reduce temperature and mitigate environmental pollution. This study investigated and compared the performance of two types of climbing green wall (CGW) and paving green wall (PGW) vegetation for temperature and noise reduction. Besides, the biological characteristics of Parthenocissus tricuspidata and Sedum lineare Thunb were also analyzed to substantiate the temperature and noise reduction performance of these plants. The results revealed that, the average temperature reduction by CGW and PGW were 4.9% ± 1.3% and 16.6% ± 7.4%, respectively, under no irrigation condition, and 18.4% ± 9.4% and 23.8% ± 8.7%, respectively, under irrigation condition. The noise reduction by CGW in high (75–80 dB), medium (50–55 dB) and low (30–35 dB) sound pressure level was 12.4, 7.5 and 5.7 dB, respectively, and 15.6, 9.3 and 7.0 dB, respectively, by PGW. The results demonstrated that green wall has an excellent effect on buildings toward temperature and noise pollution reduction. [ABSTRACT FROM AUTHOR]

The large number of vehicles plying in roads is the main cause of traffic jam and air pollution in Hanoi. In this study, the vehicle density and shares of different vehicle types, the traffic flow velocity and roadside air pollutants concentrations were monitored in Chua Boc street, a typical arterial road in the city. The shares of the motorcycle, car and bus fleets in the total on-road traffic in the street were 78.4-87.3, 12.3-20.2 and 0.4-1.4%, respectively. The high density of vehicles caused traffic jam during rush hours and considerably reduced the vehicle speed. The traffic flow velocity during non-rush and rush hours was found to vary from 26.4-34.5 and 10.3-12.1 km/h, respectively. The average concentrations of PM10, PM2.5, SO2, NO2, CO and NMVOC during the rush hours were the following: 117.1 ± 8.5, 65.2 ± 10.6, 113.5 ± 10.9, 138.5 ± 16.0, 6792 ± 998 and 451 ± 71 µg/m3, respectively, which were about 1.9-2.6 times above the levels during non-rush hours. The decrease in vehicle speed during rush hours were strongly correlated with the increase in concentration of PM10 (R2 = 0.732), PM2.5 (R2 = 0.685), SO2 (R2 = 0.578), NO2 (R2 = 0.738), CO (R2 = 0.689) and NMVOC (R2 = 0.747). High levels of these toxic air pollutants in Hanoi city posed a high health risk to humans. Facemask use was more popular among the motorcycle commuters and pedestrians, especially during rush hours, than among the people working for extended time period alongside of the street. [ABSTRACT FROM AUTHOR]