Premium
Redistribution of PM 2.5 ‐associated nitrate and ammonium during outdoor‐to‐indoor transport
Author(s) -
Liu Cong,
Wang Haixin,
Guo Hongyu
Publication year - 2019
Publication title -
indoor air
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.387
H-Index - 99
eISSN - 1600-0668
pISSN - 0905-6947
DOI - 10.1111/ina.12549
Subject(s) - nitrate , ammonium , environmental science , environmental chemistry , inorganic ions , ammonium nitrate , chemistry , particulates , environmental engineering , ion , organic chemistry
Nitrate and ammonium ions are major constituents of outdoor PM 2.5 . Human exposure to these ions occurs primarily indoors. To assess the adverse outcomes from exposure to them, it is necessary to quantify the relationships between outdoor and indoor PM 2.5 nitrate and ammonium. The relationships for the two semi‐volatile ions are more complex than those of non‐volatile PM 2.5 constituents (eg, sulfate, elemental carbon). This study presents a mechanistic description of their outdoor‐indoor relationships that incorporates a dynamic gas‐particle partitioning and key parameters such as the pH and water content of PM 2.5 . Compared to measurements of nitrate and ammonium, the model has normalized mean biases of −9% and −42% and correlation coefficients of 0.95 and 0.68 for nitrate and ammonium, respectively. This suggests satisfactory agreement for nitrate, but less strong for ammonium. Sensitivity analysis on key parameters indicates that the model generally works well across a range of values typical of indoor settings. The model's performance is sensitive to pH and water content in PM 2.5 , which control the gas‐particle partitioning process. Indoor PM 2.5 tends to be more acidic than outdoor PM 2.5 , raising potential health concern. The model provides insights in exposure assessment, source apportionment, and health‐composition attribution of indoor PM 2.5 .