With increasing atmospheric pollution and health issues associated with size of the particulate matter, it has become important to look for techniques that may improve the monitoring resolution. Magnetic bio-monitoring of particulate matter has been used in recent years in some countries as an approach for better spatial resolution that provides proxy indicators for the measurements over large areas. Delhi, which is one of the most polluted cities of not just India, but the whole world, is still probing to understand the possible sources. The present magnetic biomonitoring study was therefore, carried across different land use areas in some air pollution hotspots of Delhi, using common roadside tree species Morus alba, Ficus religiosa, Ficus variens and Ficus benghalensis to understand the magnitude and nature of the particulate pollution, and possible sources by studying magnetic properties (Magnetic susceptibility, Frequency-dependent susceptibility, S-ratio, and SIRM) of the dust deposited on leaves. Mass specific magnetic susceptibility (10⁻⁸ m³ kg⁻¹) values found to follow the order: Traffic intersection area (25.6–66.5) > Industrial area (25.4–41.3) > Residential area (13.2–30.1) > Institutional area serving as control (2.7–6.6). High magnetic susceptibility values indicated particulates with ferrimagnetic grains of anthropogenic or technogenic origin. Frequency-dependent Susceptibility indicated dominance of coarse multidomain (MD) and Pseudo Single Domain (PSD) +MD grains in industrial area and major traffic intersection. Average S ratio across all study sites ranged from 0.92 to 0.99 indicating presence of soft magnetic mineral with low coercivity. High SIRM values (10⁻⁵Am² kg⁻¹) from 58.1 to 862.3 suggested prevalence of magnetite dominating atmospheric particulates particularly in traffic intersection and industrial area, and to some extent in residential area. Morus alba and Ficus religiosa were found more suitable bio-monitors and the technique provided useful information on size, mineralogy and possible source of the particulates.

随着与颗粒物大小相关的大气污染和健康问题的增加，寻找可以提高监测分辨率的技术变得很重要。近年来，一些国家已将颗粒物的磁性生物监测用作提高空间分辨率的方法，为大面积测量提供代理指标。德里不仅是印度，而且是全世界污染最严重的城市之一，它仍在探索可能的来源。因此，目前的磁性生物监测研究是在德里一些空气污染热点的不同土地利用区域进行的，使用常见的路边树种桑白树、榕树、榕树和班加尔榕通过研究沉积在叶子上的灰尘的磁特性（磁化率、频率相关的磁化率、S 比和 SIRM），了解颗粒物污染的大小和性质以及可能的来源。质量比磁化率 (10 ^-8  m ³  kg ^-1) 值遵循以下顺序：交通路口区域 (25.6–66.5) > 工业区 (25.4–41.3) > 住宅区 (13.2–30.1) > 作为控制的机构区 (2.7–6.6)。高磁化率值表明具有人为或技术来源的亚铁磁性颗粒的颗粒。频率相关磁化率表明粗多域 (MD) 和伪单域 (PSD) +MD 晶粒在工业区和主要交通路口占主导地位。所有研究地点的平均 S 比范围为 0.92 至 0.99，表明存在具有低矫顽力的软磁性矿物。高 SIRM 值（10 ^-5 Am ² kg ^-1) 从 58.1 到 862.3 表明磁铁矿在大气颗粒物中占主导地位，特别是在交通路口和工业区，在一定程度上在住宅区。Morus alba和Ficus religiosa被发现更合适的生物监测器，该技术提供了有关颗粒大小、矿物学和可能来源的有用信息。