(soft bright music) (logo whooshing)
- [Narrator] Ground-level ozone is a pollutant that forms
when nitrogen oxides, or NOx,
combined with volatile organic compounds, or VOCs,
in the presence of sunlight.
Emissions from transportation play a role
in ozone formation,
but data gathered during the COVID-19 lockdown
has shown some unexpected findings.
The Texas Department of Transportation
and researchers with the Texas A&M Transportation Institute
have studied the data to better understand the relationship
between transportation and air quality.
- When COVID happened, we ended up seeing things
that didn't make sense, so in particular,
it was with ozone concentrations.
They were showing that,
even though traffic had gone down significantly,
we were still seeing ozone on those same days go higher
than we were expecting.
- So this study used diverse sources of data.
For transportation side,
we used TxDOT's vehicle detector data
that collects volume and speed,
hourly volume, and hourly speed,
and we also used national-level probe vehicle data
to model the transportation activities in Texas regions.
For air quality side,
we used multiple air quality monitoring stations data,
satellite images,
and we also used national-level emission inventory data.
So we developed a modeling chain consist
of transportation modeling, emission estimation,
and modeling air quality, which is estimating origin
and PM2.5 concentrations.
For ozone concentration, we used the chemical modeling,
which requires huge computational power,
so we used Texas A&M University's
high-performance research computing systems,
and for PM2.5 concentrations, we use air dispersion models.
- First is figuring out what was going on with ozone,
and it's ozone titration, so basically,
in certain VOC-limited areas,
actually dropping the NOx concentration
by reducing the number of vehicles on the road
can actually cause an increase in ozone.
- Since ozone is a combination of NOx and VOC,
the level of VOC and NOx is very important,
so the urban area is usually known as VOC-limited regimes,
which means VOC is limited, but there are plenty of NOx.
But in the rural or suburban area,
it's usually NOx-limited regimes, so it is opposite,
so that's why we observe transportation decrease,
but ozone increase in urban area like Houston and Dallas,
- We do research to try to understand
how we impact the world around us and the public,
hopefully, an efficient transportation system,
but also in terms of how that transportation system
can otherwise affect the public and how we can evaluate
and potentially even mitigate for that.
- [Narrator] For more information
and to find the publications for this project,
please visit the TxDOT research library
at the link shown below.