Reductions in traffic-related black carbon and ultrafine particle number concentrations in an urban neighborhood during the COVID-19 pandemic

Abstract

We investigated changes in traffic-related air pollutant concentrations in an urban area during the COVID-19 pandemic. The study was conducted in a mixed commercial-residential neighborhood in Somerville (MA, USA), where traffic is the dominant source of air pollution. Measurements were made between March 27 and May 14, 2020, coinciding with a dramatic reduction in traffic (71% drop in car and 46% drop in truck traffic) due to business shutdowns and a statewide stay-at-home advisory. Indicators of fresh vehicular emissions (ultrafine particle number concentration [PNC] and black carbon [BC]) were measured with a mobile monitoring platform on an interstate highway and major and minor roadways. Our results show that depending on road class, median PNC and BC contributions from traffic were 60–68% and 22–46% lower, respectively, during the lockdown compared to pre-pandemic conditions, and corresponding reductions in total on-road concentrations were 45-69% and 22-56%, respectively. A higher BC: PNC concentration ratio was observed during the lockdown period likely indicative of the higher fraction of diesel vehicles in the fleet during the lockdown. Overall, the scale of reductions in ultrafine particle and BC concentrations was commensurate with the reductions in traffic. This natural experiment allowed us to quantify the direct impacts of reductions in traffic emissions on neighborhood-scale air quality, which are not captured by the regional regulatory-monitoring network. These results underscore the importance of measurements of appropriate proxies for traffic emissions at relevant spatial scales. Our results are useful for exposure analysis as well as city and regional planners evaluating mitigation strategies for traffic-related air pollution.

How Is Wildlife Affected by the COVID-19 Pandemic? Lockdown Effect on the Road Mortality of Hedgehogs

“…During the lockdown in Poland, a significant reduction in car traffic was observed, as in other countries [ 3 , 28 , 29 , 30 , 31 , 32 ]. The following data were used as a measure of this change: Nationwide data from automatic traffic measurement stations (measuring the number of vehicles per day) showing the percentage change in car traffic in 2020 compared to 2019, from March to September [ 33 ] ( Figure 2 ); Nationwide data showing the percentage change in the number of road accidents in 2020 compared to 2019, from January to September [ 34 ] ( Figure 2 ); Local data from Chełm showing the percentage change in the number of road accidents and collisions in 2020 compared to 2019, from January to September (source: the Polish police in Chełm).…”

“…Such rapid and widespread changes in the lives of people all over the world must have an impact on the environment and wildlife [ 1 ]. Changes in air quality related to the concentration of traffic-related black carbon, carbon monoxide, nitrogen dioxide, and particulate matter PM 2.5 and PM 10 quickly began to be reported from many countries around the world [ 2 , 3 , 4 , 5 ]. Environmental noise reduction [ 6 , 7 ] and improvement to the ecological condition of highly affected beaches due to the lack of tourists were also reported [ 8 ].…”

Social-distancing Fatigue: Evidence from Real-time Crowd-sourced Traffic Data

“…Dramatic decreases in traffic have been noted in NYC 17 and many other places [18][19][20][21] in response to the pandemic, including Padova, Italy 18 and Auckland, New Zealand. 19 The study in Padova found a decrease in traffic flow (vehicle counts per unit time) in 2020 of approximately 70%, compared to 2018-2017.…”

University Students’ Self-Rated Health in Relation to Perceived Acoustic Environment during the COVID-19 Home Quarantine

“…Traffic flow composition was also altered. Heavy-duty vehicle traffic was affected much less compared with car traffic, owing to the need to maintain transportation of goods [ 27 ].…”