Measurements of NOx and Development of Land Use Regression Models in an East-African City

Christina Isaxon,Ebba Malmqvist,Michael Jerrett,Asmamaw Abera,Kristoffer Mattisson,Abebe Genetu Bayih,Geremew Sahilu Gebrie,Erin Flanagan,Yumjirmaa Mandakh,Abraham Aseffa

doi:10.3390/atmos12040519

Abstract

Air pollution causes premature mortality and morbidity globally, but these adverse health effects occur over proportionately in low- and middle-income countries. Lack of both air pollution data and knowledge of its spatial distribution in African countries have been suggested to lead to an underestimation of health effects from air pollution. This study aims to measure nitrogen oxides (NOx), as well as nitrogen dioxide (NO2), to develop Land Use Regression (LUR) models in the city of Adama, Ethiopia. NOx and NO2 was measured at over 40 sites during six days in both the wet and dry seasons. Throughout the city, measured mean levels of NOx and NO2 were 29.0 µg/m3 and 13.1 µg/m3, respectively. The developed LUR models explained 68% of the NOx variances and 75% of the NO2. Both models included similar geographical predictor variables (related to roads, industries, and transportation administration areas) as those included in prior LUR models. The models were validated by using leave-one-out cross-validation and tested for spatial autocorrelation and multicollinearity. The performance of the models was good, and they are feasible to use to predict variance in annual average NOx and NO2 concentrations. The models developed will be used in future epidemiological and health impact assessment studies. Such studies may potentially support mitigation action and improve public health.

Highlights

Epidemiological studies have shown that ambient air pollution is the single-largest environmental health risk worldwide [1]
Even though nitrogen oxides (NOx) is primarily emitted in the form of NO during combustion, which is oxidized to NO2, NO2 has often been used as marker of air pollution exposure in epidemiological studies to determine the adverse health effects such as birth outcomes in epidemiological studies [5,6]
The differences remain: the Land Use Regression (LUR) model in Durban was developed in an area with numerous industrial sources, and Durban is a larger city than Adama

Summary

Introduction

Epidemiological studies have shown that ambient air pollution is the single-largest environmental health risk worldwide [1]. Outdoor air pollution exposure is responsible for 3.3 million premature deaths [2], with some estimates putting this number as high as 8.9 million deaths per year [3]. Nitrogen oxides (NOx ) and nitrogen dioxide (NO2 ), in particular, are anthropogenically generated components of air pollution [4]. Even though NOx is primarily emitted in the form of NO during combustion, which is oxidized to NO2 , NO2 has often been used as marker of air pollution exposure in epidemiological studies to determine the adverse health effects such as birth outcomes in epidemiological studies [5,6]. The economic cost of these air pollution-derived health effects is expected to decrease the global domestic product (GDP) by one percent by 2060 [15]

Objectives

Results

Discussion

Conclusion