Impact of Traffic on Air Pollution in a Mid-Sized Urban City During Covid-19 Lockdowns

23 Pages Posted: 31 Mar 2022

See all articles by Nathan Hay

Nathan Hay

Marquette University

Otito Onwuzurike

Marquette University

Somesh Roy

Marquette University

Patrick McNamara

Marquette University

Margaret McNamara

Marquette University

Walter McDonald

Marquette University

Abstract

In this study, we evaluated the changes in air pollutant concentrations around Milwaukee, WI during and after lockdown due to the COVID-19 pandemic for a period of 126 days. Measurements of particulate matter (PM 1, 2.5 and 10), NH3, H2S, and O3+NO2, were made on a 74-kilometer route of arterial and highway roads from April to August 2020 using a Sniffer 4D sensor mounted to a vehicle. Traffic volume during measurement periods were estimated from smartphone-based traffic data. From lockdown (March 24, 2020 - June 11, 2020) to post-lockdown (June 12, 2020 – August 26, 2020) median traffic volume increased roughly 30-84%, depending upon the road type. In addition, increases in mean concentrations of NH3 (277%), PM (220% - 307%) and O3+NO2 (28%) were also observed. For both traffic and air pollutants, abrupt changes in the data were observed mid-June, shortly after lockdown measures were lifted in Milwaukee County. Indeed, traffic was able to explain up to 57% of PM, 47% of NH3, and 42% of O3+NO2 variance in pollutant concentrations on arterial and highway road segments. Two arterial roads that did not have statistically significant changes in traffic patterns during the lockdown exhibited no statistically significant trends between traffic and air quality parameters. This study demonstrated that COVID-19 lockdowns in Milwaukee, WI caused significant decreases in traffic, which in turn had a direct impact on air pollutants. It also highlights the need for traffic volume and air quality data at relevant spatial and temporal scales for accurately assessing source apportionment of combustion-based air pollutants, which cannot be captured with typical ground-based sensor systems.

Keywords: COVID-19, air pollutants, traffic, emissions

Suggested Citation

Hay, Nathan and Onwuzurike, Otito and Roy, Somesh and McNamara, Patrick and McNamara, Margaret and McDonald, Walter, Impact of Traffic on Air Pollution in a Mid-Sized Urban City During Covid-19 Lockdowns. Available at SSRN: https://ssrn.com/abstract=4068344 or http://dx.doi.org/10.2139/ssrn.4068344

Nathan Hay

Marquette University ( email )

P.O. Box 1881
Milwaukee, WI 53201-1881
United States

Otito Onwuzurike

Marquette University ( email )

P.O. Box 1881
Milwaukee, WI 53201-1881
United States

Somesh Roy

Marquette University ( email )

P.O. Box 1881
Milwaukee, WI 53201-1881
United States

Patrick McNamara

Marquette University ( email )

P.O. Box 1881
Milwaukee, WI 53201-1881
United States

Margaret McNamara

Marquette University ( email )

P.O. Box 1881
Milwaukee, WI 53201-1881
United States

Walter McDonald (Contact Author)

Marquette University ( email )

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