Quantifying Neighborhood-Scale Spatial Variations of Ozone at Open Space and Urban Sites in Boulder, Colorado Using Low-Cost Sensor Technology.

Lucy Cheadle,Michael Hannigan,Ashley Collier-Oxandale,Kira Sadighi,Lauren Deanes,Joanna Gordon Casey

doi:10.3390/s17092072

Abstract

Recent advances in air pollution sensors have led to a new wave of low-cost measurement systems that can be deployed in dense networks to capture small-scale spatio-temporal variations in ozone, a pollutant known to cause negative human health impacts. This study deployed a network of seven low-cost ozone metal oxide sensor systems (UPods) in both an open space and an urban location in Boulder, Colorado during June and July of 2015, to quantify ozone variations on spatial scales ranging from 12 m between UPods to 6.7 km between open space and urban measurement sites with a measurement uncertainty of ~5 ppb. The results showed spatial variability of ozone at both deployment sites, with the largest differences between UPod measurements occurring during the afternoons. The peak median hourly difference between UPods was 6 ppb at 1:00 p.m. at the open space site, and 11 ppb at 4:00 p.m. at the urban site. Overall, the urban ozone measurements were higher than in the open space measurements. This study evaluates the effectiveness of using low-cost sensors to capture microscale spatial and temporal variation of ozone; additionally, it highlights the importance of field calibrations and measurement uncertainty quantification when deploying low-cost sensors.

Highlights

Surface level ozone is well established as harmful to human health, causing impaired lung function in both healthy and sensitive populations [1,2,3]
In order to demonstrate the utility of low-cost sensor systems for assessing open space and urban microscale spatial variability, we deployed a fleet of seven metal oxide ozone sensor systems in the Boulder, Colorado area
The results from this study indicate that there is both intra-open space and intra-urban spatial variability of ozone on very small spatial scales ranging from 12 m spatial variability of ozone on very small spatial scales ranging from 12 m to 6.7 km

Summary

Introduction

Surface level ozone is well established as harmful to human health, causing impaired lung function in both healthy and sensitive populations [1,2,3]. Metropolitan and Northern Front Range Region of Colorado has been designated by the EPA as a “nonattainment” area for ozone since 2007 [4]. Colorado is a unique setting for surface ozone formation as urban emissions from highly populated areas and point sources such as power plants mix with emissions from nearby and rural oil and natural gas activities in the Wattenberg Gas Field. Criteria pollutants, including ozone, are continuously monitored in the U.S at standard regulatory air quality monitoring (AQM) stations. These measurements are of high quality but are sparsely distributed and unsuited for providing high spatial resolution variations in concentration [5,6,7]

Methods

Results

Conclusion