Browsing by Author "Powell, M.A."

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    COVID-19 lockdown: a rare opportunity to establish baseline pollution level of air pollutants in a megacity, India
    (Springer Science and Business Media Deutschland GmbH, 2021-02-22T00:00:00) Sahoo, P.K.; Salom�o, G.N.; da Silva Ferreira J�nior, J.; de Lima Farias, D.; Powell, M.A.; Mittal, S.; Garg, V.K.
    This paper analyses air quality data from megacity�Delhi, India, during different periods related to the COVID-19, including pre-lockdown, lockdown and unlocked (post-lockdown) (2018�2020) to determine what baseline levels of air pollutants might be and the level of impact that could be anticipated under the�COVID-19 lockdown�emission scenario. The results show that air quality improved significantly during the lockdown phases, with the most significant changes occurring in the transportation and industrially dominated areas. A pronounced decline in PM2.5 and PM10 up to 63% and 58%, respectively, was observed during the lockdown compared to the pre-lockdown period in 2020. When compared to 2018 and 2019, they were lower by up to 51% and 61%, respectively, dropping by 56% during unlock. Some pollutants (NOx and CO) dropped significantly during lockdown, while SO2 and O3 declined only slightly. Moreover, when compared between the different phases of lockdown, the maximum decline for most of the pollutants and air quality index occurred during the�lockdown phase 1; thus, this period was used to report the�COVID-19 baseline threshold values�(CBT; threshold value is the upper limit of baseline variation). Of the various�statistical methods used median + 2 median absolute deviation (mMAD)�was most suitable, indicating CBT values�of 143 and 75 ug/m3 for PM10 and PM2.5, respectively. This results although preliminary, but�it�gives a positive indication that temporary lockdown can be considered as a boon to mitigate the damage we have done to the environment. Also, this baseline levels can be helpful�as a first line of information�to set future�target limits�or to�develop effiective management policies for achieving better air quality in urban centres like Delhi. � 2021, Islamic Azad University (IAU).