Department of Environmental Engineering, Delhi Technological University, Delhi, 110042, India.
Space and Atmospheric Sciences Division, Physical Research Laboratory, Ahmedabad, 380009, India.
Chemosphere. 2024 Oct;366:143470. doi: 10.1016/j.chemosphere.2024.143470. Epub 2024 Oct 3.
Ultrafine particles (UFP) associated with air quality and health impacts are a major concern in growing urban regions. Concentrations of UFP (particles of size between 10 and 100 nm) and accumulation mode (N) (particles of size >100 and up to 1000 nm), are analyzed over a highly polluted megacity, Delhi, in conjunction with vehicular flow density, during peak (morning, and evening) and non-peak hours. UFP contributes ≥60% to total particle concentration during autumn and monsoon. UFP concentrations are about 50,000 particles per cm in winter which reduces to about 25,000 particles during monsoon. N are about 20,000 (winter) and 10,000 (monsoon) particles per cm. UFP concentration and N during peak hours are at least twice higher than those obtained in non-peak hours, confirming the dominant influence of emissions from vehicular exhaust in the study region. Seasonal analysis of UFP size distribution reveals that direct emissions dominate the particle concentrations during winter and autumn, whereas new particle formation mechanism contributes the highest in spring and summer. Assessment of inhalable particle number concentration and particle deposition in the human respiratory tract using Multiple Path Particle Dosimetry (MPPD) model, performed for the first time, shows that the order in which these particles deposit in the human respiratory tract is alveoli > bronchiole > bronchus. The deposition ranges between 10 and 18 million nanoparticles during different hours of the day, whereas the estimated inhalable particle concentration (IPN) varies between 0.5 and 1 billion. Results on the IPN during activities classified from light (walking), medium, heavy, very heavy to severe (long-distance running) provide insights into health effects on vulnerable populations. These quantitative results obtained over a megacity on hourly and seasonal variations of nanoparticles along with IPN and deposition rates for different activities are important, and are invaluable inputs for developing mitigation policies aimed to improve air quality and public health, both of which are major concerns in South Asia.
超细颗粒（UFP）与空气质量和健康影响有关，是城市地区日益关注的主要问题。在一个高度污染的特大城市德里，分析了与车辆流量密度相关的 UFP（尺寸在 10 到 100nm 之间的颗粒）和积聚模态（N）（尺寸大于 100 至 1000nm 的颗粒）浓度，分析时间涵盖了秋季和季风期的高峰时段（早晚高峰）以及非高峰时段。在秋季和季风期，UFP 占总颗粒物浓度的比例大于 60%。冬季 UFP 浓度约为每立方厘米 50000 个颗粒，季风期降至约 25000 个颗粒。N 浓度约为每立方厘米 20000 个（冬季）和 10000 个（季风）。高峰时段的 UFP 和 N 浓度至少是非高峰时段的两倍，这证实了排放物对研究区域的影响。UFP 粒径分布的季节性分析表明，在冬季和秋季，直接排放物主导着颗粒物浓度，而在春季和夏季，新粒子形成机制的贡献最大。首次使用多路径粒子剂量计（MPPD）模型评估可吸入颗粒数浓度和颗粒在人体呼吸道中的沉积，结果表明，这些颗粒在人体呼吸道中的沉积顺序为肺泡>细支气管>支气管。在一天中的不同时间，这些颗粒的沉积量在 1000 万到 1800 万之间，而估计的可吸入颗粒浓度（IPN）在 0.5 亿到 10 亿之间变化。根据从轻（散步）到中、重、极重到严重（长距离跑步）分类的活动的 IPN 结果，为脆弱人群的健康影响提供了深入了解。这些在特大城市获得的关于纳米颗粒的每小时和季节性变化、IPN 和不同活动的沉积率的定量结果，对于制定旨在改善空气质量和公共健康的缓解政策非常重要，这两个方面在南亚都是主要关注点。
