Chlorinated paraffins (CPs) are chlorinated alkane mixtures widely used as flame retardants and plasticizers in multiple industrial products. Systematic research on how homolog-specific properties affect their atmospheric behaviors is limited. Herein, we investigated the levels of short-chain CPs (SCCPs) and medium-chain CPs (MCCPs) in long-timescale, seasonal, and size-fractioned particles in the urban area of Dalian, a coastal city in northern China. The average SCCP and MCCP concentrations in particles with diameters ≤ 10 μm were 3.36 and 4.89ng/m3, respectively, and a general increase in the SCCP concentration was observed from 2.59ng/m3 in 2018 – 2019 to 7.84ng/m3 in 2021 – 2023. CP levels and patterns showed significant seasonal variation, with a higher abundance of C11-13Cl7-9 in winter and C10-12Cl5 in summer. Elevated particle levels in winter and high temperatures in summer contributed to the seasonal variations. SCCPs and MCCPs were concentrated on particles with diameters of < 1 μm and their geometric mean diameter increased with the increasing carbon and chlorine numbers. Total Daily intake of SCCP and MCCP was calculated to be 0.15 and 0.22ng/kg bw/day for adults. 53.1%, 8.5%, and 38.4% of inhaled SCCPs, and 60.6%, 7.6%, and 31.8% of inhaled MCCPs deposited into the head airway, tracheobronchial region, and alveolar region, respectively. This study reports on how homolog-specific physicochemical properties alter the temporal variations, size distributions, and inhaled fractions of CPs. Environmental implicationCPs, emerging POPs, have garnered global attention owing to their considerable environmental contamination and high toxicity. The atmosphere is the key microenvironment where emission, transport, and exposure of chlorinated paraffins (CPs) happen. Atmospheric behaviors of CPs varied a lot, and factors altering these processes were not fully elucidated. This study reports different temporal variations, size distribution, and inhaled fractions for SCCP and MCCP homolog, and reveals that homolog-specific physicochemical properties significantly contributed to the variations. This study also provided scientific evidence for the model simulation of CP transport and exposure, with an emphasis on CP homolog variations.