Mauro Masiol1, Stefania Squizzato1, David Chalupa2, David Q. Rich1,2, Philip K. Hopke 1,3


Department of Public Health Sciences, University of Rochester Medical Center, Rochester, NY 14642, USA
Department of Environmental Medicine, University of Rochester Medical Center, Rochester, NY 14642, USA
Center for Air Resources Engineering and Science, Clarkson University, Potsdam, NY 13699, USA



Received: February 12, 2018
Revised: April 16, 2018
Accepted: April 19, 2018
Download Citation: ||https://doi.org/10.4209/aaqr.2018.02.0056  


Cite this article:
Masiol, M., Squizzato, S., Chalupa, D., Rich, D.Q. and Hopke, P.K. (2018). Evaluation and Field Calibration of a Low-cost Ozone Monitor at a Regulatory Urban Monitoring Station. Aerosol Air Qual. Res. 18: 2029-2037. https://doi.org/10.4209/aaqr.2018.02.0056


HIGHLIGHTS

  • A low-cost ozone monitor & FEM were located at an urban air quality station.
  • A 12% overestimation was found with respect to FEM analyzer.
  • Differences in response were investigated using air quality and weather data.
  • Three corrections are proposed to produce “FEM-like” ozone concentrations.

ABSTRACT


The performance of a low-cost ozone monitor (the Aeroqual Series 500 portable gas monitor coupled with a metal oxide sensor for ozone; model OZL) was assessed under field conditions. Ten ozone monitors were initially calibrated in clean-air laboratory conditions and tested at controlled ozone concentrations of 5 to 100 ppb. Results showed good linearity and a fast response with respect to a conventional research-grade ozone monitor. One monitor was then co-located at a regulatory air quality monitoring station that uses a U.S. federal equivalent method (FEM) ozone analyzer. Raw data from the Aeroqual monitor collected over 4 months (June–October) at a 10-minute time-resolution showed good agreement (r2 = 0.83) with the FEM values but with an overestimation of ~12%. Data were averaged to different time resolutions; 1-h time averaged concentrations showed the best fit with the FEM results (r2 = 0.87). An analysis of the ratio of FEM/monitor concentrations against chemical and meteorological variables suggested potential interference due to temperature, relative humidity, nitrogen oxides, and volatile organic compounds. Three correction models using temperature, humidity, and nitrogen dioxide (NO2) were then tested to better relate the monitor concentrations to the FEM values. Temperature and humidity are two variables commonly available (or easily measurable) at sampling sites. The model (#3) that added NO2 did not substantially improve the fit. Thus, the proposed models with only temperature and humidity can be easily adopted and adapted by any user. The corrected data explained up to 91% of the variance and showed a statistically significant improvement in the fit as well as a decreased influence from the interfering variables on the diurnal and weekly patterns. The correction models were also able to lower the effect of seasonal temperature changes, allowing the use of the monitors over long-term sampling campaigns. This study demonstrated that the Aeroqual ozone monitors can return “FEM-like” concentrations after appropriate corrections. Therefore, data provided by a network of monitors could determine the intra-urban spatial variations in ozone concentrations. These results suggest that these monitors could provide more accurate human exposure assessments and thereby reduce exposure misclassification and its resulting bias in epidemiological studies.


Keywords: Semiconductor gas sensor; Tropospheric ozone; Urban air pollution; Air pollution exposure.

 



Don't forget to share this article 

 

Subscribe to our Newsletter 

Aerosol and Air Quality Research has published over 2,000 peer-reviewed articles. Enter your email address to receive latest updates and research articles to your inbox every second week.

Latest coronavirus research from Aerosol and Air Quality Research

2018 Impact Factor: 2.735

5-Year Impact Factor: 2.827


SCImago Journal & Country Rank

Aerosol and Air Quality Research (AAQR) is an independently-run non-profit journal, promotes submissions of high-quality research, and strives to be one of the leading aerosol and air quality open-access journals in the world.