Traffic Plummeted as Stay-At-Home Order for Coronavirus Leads to an Uplift of Air Quality
Chicago skyline. Photo by Nicole Shih.
CHICAGO – The international COVID-19 pandemic has brought with it a feeling of fear and anxiousness to people caused by rising death tolls and the constraint of limiting people from traveling outdoors. The financial impact felt by industries and companies has drastically changed lives, too. But asides from all these negative impacts, can people expect something bright in the future?
Air quality can be something people could look at on the bright side.
After Mayor Lori E. Lightfoot joined Ill. Gov. J.B. Pritzker on March 20 announced a statewide stay-at-home order which took effect on March 21 at 5 p.m., traffic on roads and highways plummeted, leading to an uplift for the environment.
According to NASA, the primary chemical air pollutant coming out from vehicles’ tailpipes is nitrogen dioxide (NO2). Therefore, the reduction of the emission of NO2 could be an indicator of the decrease of human activities.
The map below shows NO2 emission in Chicagoland in March 2019 and March 2020, respectively. The lower NO2 emission inferred less traffic on roads and fewer human activities.
"Photo Credits: Before Descartes Labs / Sentinel-5p satellite After Descartes Labs / Sentinel-5p satellite"
The other two pollutants that are considered to be metrics of air quality are ozone and particulate matter. Both of them could form in the atmosphere through chemical reaction and further affect human health harmfully.
In a 2019 report, American Lung Association revealed that Chicago ranked the 18th most polluted city in the U.S. for ozone pollution.
“Chicago residents should be aware that we’re breathing unhealthy air, largely caused by hotter days and vehicle emissions, placing our health and lives at risk,” said Angela Tin, the national senior director for clean air initiatives for the American Lung Association, in the 2019 report.
The Environmental Protection Agency (EPA) also developed the Air Quality Index (AQI) to give people information about how clean or polluted the outdoor air is, along with the information regarding associated health concerns.
The EPA’s AirNow website provides real-time air quality data, which ozone and particulate matter make up the majority of the data.
The tile plot below shows the daily AQI values in Chicagoland, Naperville and Elgin from 2018 to 2020. There are a few days showing orange and red in 2018 and 2019, indicating unhealthy air quality people were breathing in those days.
Source: U.S. EPA AirData / Generated: April 16, 2020
EPA Chicago office stated that the state government, who conducts the main air quality monitoring, does not require to submit their air quality data to EPA’s Air Quality System (AQS) until the end of June 2020; therefore, the real-time AQI data for 2020 gathering from AirNow is not fully verified through the quality assurance procedures.