Size-segregated deposition of atmospheric elemental carbon (EC) in the human respiratory system: A case study of the Pearl River Delta, China

• Published in: The Science of the total environment 2020-03, Vol.708, p.134932, Article 134932
• Main Authors: Jia, Shiguo, Zhang, Qi, Sarkar, Sayantan, Mao, Jingying, Hang, Jian, Chen, Weihua, Wang, Xuemei, Yuan, Luan, Yang, Liming, Ye, Guanqiong, Zhou, Shengzhen
• Format: Article
• Language: English
• Subjects: Adult; Aerosols; Air Pollutants; Carbon; Child; China; Elemental carbon (EC); Exposure assessment; Humans; Infant; Particle dosimetry model; Particle Size; Particulate Matter; Respiratory System; Rivers; Size distribution
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2019.134932

[Display omitted] •Age- and physical exertion-specific deposition study of EC in the respiratory system.•Effects of seasonality and haze on human exposure to EC in a high population urban area.•Use of inverted particle size distribution provides significant insights into human exposure from EC deposition. It has increasingly become apparent in recent years that atmospheric elemental carbon (EC) is potentially a more sensitive indicator of human health risks from ambient aerosol exposure compared to particulate mass. However, a comprehensive evaluation of the factors affecting EC exposure is lacking so far. To address this, we performed measurements of size-segregated EC in Guangzhou, China, followed by an estimation of deposition in the human respiratory system. Most ambient EC was in the fine mode suggesting significant cloud processing, and ~40% was deposited in the human respiratory tract, with predominant deposition in the head region (47%), followed by the pulmonary (30%) and tracheobronchial (23%) regions. A significant fraction (36%) of deposited EC were coarse particles indicating the need to consider coarse-mode EC in future health effect studies. Infants and children exhibited greater vulnerability to EC exposure than adults, and the deposition amount varied linearly with breathing rate, a proxy for physical exertion. The nature of breathing was found to constrain EC inhalation significantly, with oronasal breathing associated with lower total deposition and nasal breathing leading to lower deposition in the tracheobronchial and pulmonary regions. Overall, these observations strengthen the need to include EC as an additional air quality indicator.