Quantification of Size Segregated Particulate Matter Deposition in Human Airways

Background: Air pollution has become a significant concern in both urban and rural sectors due to its catastrophic effect on human health and the environment. Particulate matter (PM) is crucial among criteria pollutants and is well correlated with human mortality and morbidity. Based on aerodynamic size, PM is classified into coarse (PM10) and fine (PM2.5 and PM1). A recent study by World Health Organization showed that PM has caused 7 million premature deaths globally. Also, the International Agency for Research on Cancer (IARC) identified PM as carcinogenic as it is directly related to lung cancer. Human airway is the primary pathway for PM to enter the human body. Hence the study on coarse and fine PM deposition in the human respiratory tract is essential for health risk assessments.Materials and Methods: Hourly measurements of PM10, PM2.5 and PM1 are measured during a winter using Grimm aerosol spectrometer near an arterial roadside in Chennai city of Tamil Nadu, India. PM deposition in the human airway is investigated using the Multiple-Path Particle Deposition Model (MPPD) version 3.04. In MPPD model, the stochastic structure which depicts the real human lung is considered. The deposition in MPPD model is assessed for three size fractions, i.e. PM10, PM2.5 and PM1 under different breathing scenarios viz. nasal, oral, and oronasal.Results: Highest total deposited mass rate obtained from the MPPD model for PM10, PM2.5, and PM1 are 942 ng min-1, 345 ng min-1, and 104 ng min-1, respectively. The maximum deposited mass rate is also assessed in the head (PM10 = 904 ng min-1; PM2.5 = 244 ng min-1; PM1 = 57 ng min-1), tracheobronchial (PM10 = 284 ng min-1; PM2.5 = 60 ng min-1; PM1 = 24 ng min-1) and pulmonary (PM10 = 32 ng min-1; PM2.5 = 89 ng min-1; PM1 = 27 ng min-1) regions. In the head region, maximum deposition is caused by nasal breathing; whereas, tracheobronchial (TB) and pulmonary regions, the oral breathing leads to higher deposition. Results also showed that for all PM sizes the lobe wise depositions are in the following order: right upper > left lower > left upper > right middle > right lower. Further, the airway clearance results indicated that PM removal is faster in the TB region than the alveolar region.Conclusion: PM10 has a higher deposition in the head region whereas PM2.5 and PM1 deposition is higher in the TB and pulmonary regions. This indicates that PM deposition inside lungs is influenced by its size and several other deposition mechanisms viz. inertial impaction, sedimentation, diffusion and interception. Further, this study results can be utilized for assessing health risks such as oxidative potential and toxicity of deposited PM

Lockdown Effects on Air Quality in Megacities During the First and Second Waves of COVID-19 Pandemic

Air pollution is among the highest contributors to mortality worldwide, especially in urban areas. During spring 2020, many countries enacted social distancing measures in order to slow down the ongoing COVID-19 pandemic. A particularly drastic measure, the “lockdown”, urged people to stay at home and thereby prevent new COVID-19 infections during the first (2020) and second wave (2021) of the pandemic. In turn, it also reduced traffic and industrial activities. But how much did these lockdown measures improve air quality in large cities, and are there differences in how air quality was affected? Here, we analyse data from two megacities: London as an example for Europe and Delhi as an example for Asia. We consider data during first and second-wave lockdowns and compare them to 2019 values. Overall, we find a reduction in almost all air pollutants with intriguing differences between the two cities except Delhi in 2021. In London, despite smaller average concentrations, we still observe high-pollutant states and an increased tendency towards extreme events (a higher kurtosis of the probability density during lockdown) during 2020 and low pollution levels during 2021. For Delhi, we observe a much stronger decrease in pollution concentrations, including high pollution states during 2020 and higher pollution levels in 2021. These results could help to design policies to improve long-term air quality in megacities

Heating and lighting: understanding overlooked energy-consumption activities in the Indian residential sector

Understanding the climate impact of residential emissions starts with determining the fuel consumption of various household activities. While cooking emissions have been widely studied, non-cooking energy-consumption activities in the residential sector such as heating and lighting, have been overlooked owing to the unavailability of data at national levels. The present study uses data from the Carbonaceous Aerosol Emissions, Source Apportionment and Climate Impacts (COALESCE) project, which consists of residential surveys over 6000 households across 49 districts of India, to understand the energy consumed by non-cooking residential activities. Regression models are developed to estimate information in non-surveyed districts using demographic, housing, and meteorological data as predictors. Energy demand is further quantified and distributed nationally at a 4 × 4 km resolution. Results show that the annual energy consumption from non-cooking activities is 1106 [201] PJ, which is equal to one-fourth of the cooking energy demand. Freely available biomass is widely used to heat water on traditional stoves, even in the warmer regions of western and southern India across all seasons. Space heating (51%) and water heating (42%) dominate non-cooking energy consumption. In comparison, nighttime heating for security personnel (5%), partly-residential personal heating by guards, dominant in urban centers and kerosene lighting (2%) utilize minimal energy. Biomass fuels account for over 90% of the non-cooking consumption, while charcoal and kerosene make up the rest. Half of the energy consumption occurs during winter months (DJF), while 10% of the consumption occurs during monsoon, when kerosene lighting is the highest. Firewood is the most heavily used fuel source in western India, charcoal in the northern hilly regions, agricultural residues and dung cake in the Indo-Gangetic plains, and kerosene in eastern India. The study shows that ∼20% of residential energy consumption is on account of biomass-based heating and kerosene lighting activities