Development and intercity transferability of land-use regression models for predicting ambient PM<sub>10</sub>, PM<sub>2.5</sub>, NO<sub>2</sub> and O<sub>3</sub> concentrations in northern Taiwan

Abstract

Abstract. To provide long-term air pollutant exposure estimates for epidemiological studies, it is essential to test the feasibility of developing land-use regression (LUR) models using only routine air quality measurement data and to evaluate the transferability of LUR models between nearby cities. In this study, we developed and evaluated the intercity transferability of annual-average LUR models for ambient respirable suspended particulates (PM10), fine suspended particulates (PM2.5), nitrogen dioxide (NO2) and ozone (O3) in the Taipei–Keelung metropolitan area of northern Taiwan in 2019. Ambient PM10, PM2.5, NO2 and O3 measurements at 30 fixed-site stations were used as the dependent variables, and a total of 156 potential predictor variables in six categories (i.e., population density, road network, land-use type, normalized difference vegetation index, meteorology and elevation) were extracted using buffer spatial analysis. The LUR models were developed using the supervised forward linear regression approach. The LUR models for ambient PM10, PM2.5, NO2 and O3 achieved relatively high prediction performance, with R2 values of > 0.72 and leave-one-out cross-validation (LOOCV) R2 values of > 0.53. The intercity transferability of LUR models varied among the air pollutants, with transfer-predictive R2 values of > 0.62 for NO2 and < 0.56 for the other three pollutants. The LUR-model-based 500 m × 500 m spatial-distribution maps of these air pollutants illustrated pollution hot spots and the heterogeneity of population exposure, which provide valuable information for policymakers in designing effective air pollution control strategies. The LUR-model-based air pollution exposure estimates captured the spatial variability in exposure for participants in a cohort study. This study highlights that LUR models can be reasonably established upon a routine monitoring network, but there exist uncertainties when transferring LUR models between nearby cities. To the best of our knowledge, this study is the first to evaluate the intercity transferability of LUR models in Asia.

Development of an integrated model framework for multi-air-pollutant exposure assessments in high-density cities and the implications for epidemiological research

“…In the PM module, our PM10 and PM2.5 exposure models achieved remarkable predictive accuracy, comparable with or higher than those of the traditional LUR studies (Tables 2 and S3; Supplementary Text S2). Following our previous study of Li et al (2021), in the PM module, we established LUR exposure models of PM10 TC, PM10 NO3 -, PM10 SO4 2-, and PM10 Cd, with model R 2 values higher than 0.92 (Table S3). The statistical performance may be over-fitted given that the sample size is relatively small.…”

“…The spatial variation of air pollution can be used for hotspot identification for air quality management and exposure assessment in epidemiological studies using the geospatial locations of the subjects (Crouse et al, 2015;Jones et al, 2020;Li et al, 2021). The major explanation for the spatial differences in concentration of multiple air pollutants was the differences in their emission sources (Cai et al, 2020;Jin et al, 2019;Levy et al, 2014;Wu et al, 2017).…”

“…Hong Kong (latitude 22°08'N and 22°35'N, longitude 113°49'E and 114°31'E) is a mountainous high-density and high-rise city situated at the southeast coast of the Pearl River Delta (PRD) region, China (Li et al, 2018;Li et al, 2020;Yim et al, 2009). Hong Kong has a total land area of about 1100 km 2 , of which 24% is built-up area.…”

“…Hong Kong is characterized by cool and dry winters with an average temperature of 19 o C, and hot and humid summers with afternoon temperatures often above 31 o C and night temperatures around 26 o C (HKO, 2020). Hong Kong is typically influenced by the transboundary air pollution issue, when polluted air masses are transported from the PRD region and beyond to the region in winter (Lee et al, 2017;Li et al, 2020;Yim, 2020). The traffic density in Hong Kong is among the highest in the world, with 839,882 registered vehicles on 2100 km of road in 2017 (HKTD, 2020).…”

“…Rappazzo et al, 2021;Requia et al, 2019;Wang et al, 2022b). To the best of our knowledge, none of these previous studies have comprehensively evaluated the spatial heterogeneity among a large set of air pollutants (e.g., particles and their chemical species, and gaseous pollutants) (Cai et al, 2020;Hoek et al, 2008;Li et al, 2021). Thus, it is essential to explore the establishment of an integrated multi-air-pollutant model framework to support epidemiological studies to isolate the health effects of multiple air pollutants.…”