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Many studies have focused mainly on the thermal and energy performance of VGSs on a building scale; however, little is known about the cooling effect of VGSs in street canyons and its response to different aspect ratios (building height/street width, H/W). Therefore, a scaled outdoor experiment was conducted to investigate the spatiotemporal variation of the urban wind and thermal environment caused by west-facing vertical greenery systems (VGSs) in street canyons with H/W = 1 and 2 in the subtropical city of Guangzhou, China. On a typical hot day (26th Oct. 2021), VGSs reduced wind speed by 38.0 % and 21.0 % in street canyons with H/W = 1 and 2, respectively. Compared with the reference cases, the temperature regimes of VGS cases (H/W = 1 and 2), including west-facing wall temperature (T w-west ), east-facing wall temperature (T w-east ), ground temperature (T g ), and air temperature (T a ), were all significantly decreased. Because of the cooling effect of VGSs, the maximum reduction of T w-west in the upper level of street canyons with H/W = 1 and 2 was 20.3 and 16.8 °C, respectively. The maximum reduction of T g in the center of the VGS case with H/W = 2 was 4.6 °C, which was more pronounced than in the VGS case with H/W = 1 (1.8 °C). The maximum reduction of T a at the pedestrian level along the central axis of street canyons with H/W = 1 and 2 was 0.8 and 1.6 °C, respectively, which was more pronounced than at the upper level. The reduction of T w-west in the upper level and of T g and T a in the VGS case with H/W = 2 was greater than that in the VGS case with H/W = 1 due to lower wind speed and albedo., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The aim of the present study was to examine Air Pollution Tolerance Index (APTI) of some climber plant species to develop vertical gardens in Varanasi city which has characteristics of tall building and narrow roads. This condition results in street canyon like structure and hinders the vertical dispersal of air pollutants. We have selected 24 climber plant species which are commonly found in of Varanasi city. Chosen plants can be easily grown either in planter boxes or directly in the ground, with a vertical support they can climb on walls to form green walls or vertical garden. Air Pollution Tolerance Index (APTI) of the selected plant species was calculated and plants with higher APTI are recommended for the development of Vertical garden. Highest APTI was noted for Ipomoea palmata (25.39) followed by Aristolochia elegans (23.28), Thunbergia grandiflora (23.14), Quisqualis indica (22.42), and Clerodendrum splendens (22.36). However, lowest APTI value (8.75) was recorded for the species Hemidesmus indicus. Moreover, the linear regression analysis has revealed a high positive correlation between APTI and ascorbic acid content (R 2 =0.8837) and positive correlation between APTI and Chlorophyll content (R 2 =0.6687). On the basis of higher APTI values (greater than 17), nine species of climber plants viz. I. palmata, T. grandiflora, C. splendens, A. elegans, Q. indica, Petria volubilis, Antigonon leptopus, Cryptolepis buchuanni and Tinospora cordifolia have been recommended to develop vertical greenery systems in a compact tropical city., (Copyright © 2015 Elsevier Inc. All rights reserved.)