Monitoring PM2.5 in the Atmosphere by Using Terahertz Time-Domain Spectroscopy

• DOI: 10.1007/s10762-016-0283-8
• Publication Date: 2016-05-12T08:18:43Z
• Authors: Honglei Zhan; Kun Zhao; Rima Bao; Lizhi Xiao
• Keywords: Absorbance

The real-time monitoring of the air pollution with multiple sources is of great significance for pollution control and environmental protection. In this paper, we presented a study of terahertz time-domain spectroscopy (THz-TDS) as a direct tool for monitoring the component and content of PM2.5 in atmosphere. Due to the THz absorption, the intensities of the peaks in THz-TDS decreased with the augment of PM2.5 and were proportional to the PM2.5 content. The ratio of absorbance A to PM2.5 reflected a basically unchanged tendency, indicating the little change of principal elements under the pollution degree. In the high-pollution condition, a lot of SO2 from vehicle and factory was emitted into air. The elements, such as S and O from anions, had a stronger absorption effect in THz range. Based on the absorbance spectra, the absorption tendencies with PM2.5 over the whole range were validated by principal component analysis and the quantitative model with a high correlation was built by using back propagation artificial neural network. BPANN model improved the precision of linear fitting between peak intensities and PM2.5. The research demonstrates that THz-TDS is a promising tool for fast, direct, and reliable monitoring in environmental applications.