Issue 8, 2019

Assessing indoor gas phase oxidation capacity through real-time measurements of HONO and NOx in Guangzhou, China

Abstract

The hydroxyl radical (OH) is one of the most important oxidants controlling the oxidation capacity of the indoor atmosphere. One of the main OH sources indoors is the photolysis of nitrous acid (HONO). In this study, real-time measurements of HONO, nitrogen oxides (NOx) and ozone (O3) in an indoor environment in Guangzhou, China, were performed under two different conditions: (1) in the absence of any human activity and (2) in the presence of cooking. The maximum NOx and HONO levels drastically increased from 15 and 4 ppb in the absence of human activity to 135 and 40 ppb during the cooking event, respectively. The photon flux was determined for the sunlit room, which has a closed south-east oriented window. The photon flux was used to estimate the photolysis rate constants of NO2, J(NO2), and HONO, J(HONO), which span the range between 8 × 10−5 and 1.5 × 10−5 s−1 in the morning from 9:30 to 11:45, and 8.5 × 10−4 and 1.5 × 10−4 s−1 at noon, respectively. The OH concentrations calculated by photostationary state (PSS) approach, observed around noon, are very similar, i.e., 2.4 × 106 and 3.1 × 106 cm−3 in the absence of human activity and during cooking, respectively. These results suggest that under “high NOx” conditions (NOx higher than a few ppb) and with direct sunlight in the room, the NOx and HONO chemistry would be similar, independent of the geographic location of the indoor environment, which facilitates future modeling studies focused on indoor gas phase oxidation capacity.

Graphical abstract: Assessing indoor gas phase oxidation capacity through real-time measurements of HONO and NOx in Guangzhou, China

Supplementary files

Article information

Article type
Paper
Submitted
25 avr. 2019
Accepted
03 juil. 2019
First published
04 juil. 2019

Environ. Sci.: Processes Impacts, 2019,21, 1393-1402

Assessing indoor gas phase oxidation capacity through real-time measurements of HONO and NOx in Guangzhou, China

J. Liu, S. Li, J. Zeng, M. Mekic, Z. Yu, W. Zhou, G. Loisel, A. Gandolfo, W. Song, X. Wang, Z. Zhou, H. Herrmann, X. Li and S. Gligorovski, Environ. Sci.: Processes Impacts, 2019, 21, 1393 DOI: 10.1039/C9EM00194H

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