High-resolution urban air pollution mapping.

Variation in urban air pollution arises because of complex spatial, temporal, and chemical processes, which profoundly affect population exposure, human health, and environmental justice. This Review highlights insights from two popular in situ measurement methods-mobile monitoring and dense sensor networks-that have distinct but complementary strengths in characterizing the dynamics and impacts of the multidimensional urban air quality system. Mobile monitoring can measure many pollutants at fine spatial scales, thereby informing about processes and control strategies.

Integrating Mobile and Fixed-Site Black Carbon Measurements to Bridge Spatiotemporal Gaps in Urban Air Quality.

Urban air pollution can vary sharply in space and time. However, few monitoring strategies can concurrently resolve spatial and temporal variation at fine scales. Here, we present a new measurement-driven spatiotemporal modeling approach that transcends the individual limitations of two complementary sampling paradigms: mobile monitoring and fixed-site sensor networks.

Meteorology governs the variation of Delhi's high particulate-bound chloride levels.

A significant number of past studies have reported Delhi to witness some of the highest levels of particulate-bound chloride compared to anywhere else in the world. The present study employs long-term, highly time-resolved chloride measurements at the IIT Delhi campus from February 2020 to April 2021. The present work sheds light on the dependence of high chloride levels in Delhi on the winds from the northwest direction.

Variation in chemical composition and sources of PM during the COVID-19 lockdown in Delhi.

The Government of India (GOI) announced a nationwide lockdown starting 25th March 2020 to contain the spread of COVID-19, leading to an unprecedented decline in anthropogenic activities and, in turn, improvements in ambient air quality. This is the first study to focus on highly time-resolved chemical speciation and source apportionment of PM to assess the impact of the lockdown and subsequent relaxations on the sources of ambient PM in Delhi, India. The elemental, organic, and black carbon fractions of PM were measured at the IIT Delhi campus from February 2020 to May 2020.