The nationwide lockdown in India to flatten the pandemic COVID-19 curve has resulted in the reduction of anthropogenic emission sources to a great extent. This study reports change in air quality and its impact on the environment during the unique lockdown scenario at Bhubaneswar, a coastal smart city in east India. The urban air shows a remarkable reduction in the mean pollutant levels influenced by traffic emission viz. NO x (~67 %) and BC (~47 %) during lockdown over the pre-lockdown. Comparatively, a lower reduction of CO (~14 %) is attributed to the dominance of natural atmospheric chemical regulation and biogenic sources in addition to anthropogenic contributions. In addition to the lockdown, frequent rain events due to depression in the Bay of Bengal (BoB) also had a significant role in the reduction of the primary pollutants over the study site. An enhancement of secondary pollutant viz. O 3 (~3%) with a distinct diurnal pattern was observed during the first phase of lockdown over the pre-lockdown period. An anti-correlation between O 3 and NO x during pre-lockdown points to a higher O 3 production potential with decreasing NO x. While a reduction in the titration of O 3 due to suppression of fresh NO emissions led to accumulation of O 3 in the first phase of lockdown, inhibited photochemistry due to cloudy skies as well as reduction in precursors led to lower O 3 values during the later phases of lockdown.
Airborne particulate matter contains biological entities from various anthropogenic/biogenic activities. Within 1 nm–100 μm size, these are carried to long distances through various external agents. Identified as potential pathogens, they bring forth substantial economic losses in many parts of the world. Despite these shortcomings, bio-aerosols play a vital role in cloud condensation, ice nucleation, precipitation and various atmospheric processes affecting the hydrological cycle in general. Furthermore, bio-aerosols play a decisive role in the dispersal of reproductive plant parts and fungal spores, which play important roles in the evolution and sustenance of ecosystems. However, there remains substantial knowledge on air micro-biome with respect to their occurrence, transformation, role in climate change, interaction and impact on living organisms, agriculture and ecosystem. The current COVID-19 pandemic is a wakeup call for retrospective analysis of airborne particles to reduce their emission, transmission and health risk hazards while understanding their impact on various atmospheric processes. This chapter identifies the various types of bio-aerosols and systematically includes their prime role in the climatic processes, pathogenicity to the exposed flora and fauna along with an exclusive interrogation into their types and characterisation over the Indian subcontinent with a hugely diverging population and pollution panorama.
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