Physical, optical and radiative attributes of atmospheric aerosols produced due to bonfire during the Holika festival

Abstract

Air pollution is a global health issue, and events like forest fires, agricultural burning, dust storms, and fireworks can significantly worsen it. Festivals involving fireworks and wood-log fires, such as Diwali and Holi, are key examples of events that impact local air quality. During Holi, the ritual of Holika involves burning of biomass that releases large amounts of aerosols and other pollutants. To assess the impact of Holika burning, observations were conducted from March 5th to March 18th, 2017. On March 12th, 2017, around 1.8 million kg of wood and biomass were openly burned in about 2250 units of Holika, located in and around the Varanasi city (25.23 N, 82.97 E, ∼82.20 m amsl). As the Holika burning event began the impact on the Black Carbon (BC), particulate matter 10 & 2.5 (PM₁₀ and PM_2.5), sulphur dioxide (SO₂), oxides of nitrogen (NO_x), ozone (O₃) and carbon monoxide (CO) concentration were observed. Thorough optical investigations have been conducted to better comprehend the radiative effects of aerosols produced due to Holika burning on the environment. The measured AOD at 500 nm values were 0.315 ± 0.072, 0.392, and 0.329 ± 0.037, while the BC mass was 7.09 ± 1.78, 9.95, and 7.18 ± 0.27 μg/m³ for the pre-Holika, Holika, and post-Holika periods. Aerosol radiative forcing at the top of the atmosphere (ARF-TOA), at the surface (ARF-SUR), and in the atmosphere (ARF-ATM) are 2.46 ± 4.15, −40.22 ± 2.35, and 42.68 ± 4.12 W/m² for pre-Holika, 6.34, −53.45, and 59.80 W/m² for Holika, and 5.50 ± 0.97, −47.11 ± 5.20, and 52.61 ± 6.17 W/m² for post-Holika burning. These intense observation and analysis revealed that Holika burning adversely impacts AQI, BC concentration and effects climate in terms of ARF and heating rate.