The influence of odd-even car trial on fine and coarse particles in Delhi.
The odd-even car trial scheme, which reduced car traffic between 08.00 and 20.00 h daily, was applied from 1 to 15 January 2016 (winter scheme, WS) and 15-30 April 2016 (summer scheme, SS). The daily average PM2.5and PM10exceeded national standards, with highest concentrations (313 μg m-3and 639 μg m-3, respectively) during winter and lowest (53 μg m-3and 130 μg m-3) during the monsoon (June-August). PM concentrations during the trials can be interpreted either as reduced or increased, depending on the periods used for comparison purposes. For example, hourly average net PM2.5and PM10(after subtracting the baseline concentrations) reduced by up to 74% during the majority (after 1100 h) of trial hours compared with the corresponding hours during the previous year. Conversely, daily average PM2.5and PM10were higher by up to 3-times during the trial periods when compared with the pre-trial days. A careful analysis of the data shows that the trials generated cleaner air for certain hours of the day but the persistence of overnight emissions from heavy goods vehicles into the morning odd-even hours (0800-1100 h) made them probably ineffective at this time. Any further trial will need to be planned very carefully if an effect due to traffic alone is to be differentiated from the larger effect caused by changes in meteorology and especially wind direction.
Department of Civil and Environmental Engineering, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH, United Kingdom; Environmental Flow (EnFlo) Research Centre, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH, United Kingdom. Electronic address: P.Kumar@surrey.ac.uk.
Prashant
P
Kumar
Department of Civil Engineering, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India; Presently at: CSIR-National Environmental Engineering and Research Institute, Delhi Zonal Centre, India.
Sunil
S
Gulia
Division of Environmental Health & Risk Management, School of Geography, Earth & Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom; Department of Environmental Sciences/Center of Excellence in Environmental Studies, King Abdulaziz University, Jeddah 21589, Saudi Arabia.
Roy M
RM
Harrison
Department of Civil Engineering, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
Mukesh
M
Khare
D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000032:analysis / Q000706:statistics & numerical data; D001336:Automobiles / Q000706:statistics & numerical data*; D004784:Environmental Monitoring; D007194:India; D018986:Motor Vehicles; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis*; D012621:Seasons; D001335:Vehicle Emissions / Q000032:analysis*; D014919:Wind
D000393:Air Pollutants; D052638:Particulate Matter; D001335:Vehicle Emissions
Living labs; Odd–even car trial; PM(10) and PM(2.5); Pollution exposure; Traffic emissions