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To mitigate the impacts of the pandemic of coronavirus disease 2019 (COVID-19), the Indian government implemented lockdown measures on 24 March 2020, which prohibited unnecessary anthropogenic activities, thus leading to a significant reduction in emissions. To investigate the impacts of this lockdown measure on air quality in India, we used the Community Multi-Scale Air Quality (CMAQ) model to estimate the changes of key air pollutants. From pre-lockdown to lockdown periods, improved air quality is observed in India, indicated by the lower key pollutant levels such as PM 2.5 (- 26 %), maximum daily 8 h average ozone (MDA8 O 3) (- 11 %), NO 2 (- 50 %), and SO 2 (- 14 %). In addition, changes in these pollutants show distinct spatial variations with the more important decrease in northern and western India. During the lockdown, our results illustrate that such emission reductions play a positive role in the improvement of air quality. Significant reductions of PM 2.5 concentration and its major components are predicted, especially for secondary inorganic aerosols that are up to 92 %, 57 %, and 79 % for nitrate (NO 3-), sulfate (SO 42-), and ammonium (NH 4+), respectively. On average, the MDA8 O 3 also decreases 15 % during the lockdown period although it increases slightly in some VOC-limited urban locations, which is mainly due to the more significant reduction of NO x than VOCs. More aggressive and localized emission control strategies should be implemented in India to mitigate air pollution in the future. [ABSTRACT FROM AUTHOR]

There have been few investigations of the phase relationship between the Indian summer monsoon (ISM) and the East Asian summer monsoon (EASM) during the last glacial period. We present multi-proxy mineralogical and geochemical records from a peat core taken from the Baoxiu Basin, central Yunnan, southwest China, to investigate changes in chemical weathering and climate associated with the ISM in southwest China spanning the interval ∼32.7–11.4 ka BP. The results suggest that the LGM period (23–18 ka BP) was characterized by cold and dry climatic conditions. A comparison of proxy data from Baoxiu peat with other related proxy climate records reveals that broadly synchronous variations in the ISM and EASM on orbital timescales can be attributed to solar radiation forcing in the Northern Hemisphere. In addition, four synchronous weak millennial-scale monsoonal events coincide well with cooling events recorded in the NGRIP ice core (corresponding to the Younger Dryas, and Heinrich events H1, H2, and H3). Significantly, the strengths of the two Asian monsoons show an inverse relationship during the interval 23–19 ka BP, probably resulting from El Niño-like conditions in the tropical Pacific. [ABSTRACT FROM AUTHOR]