IEEE Consumer Electronics Magazine - January/February 2023 - 29

corresponding station and is limited to PM2:5 as
other particle sizes were only intermittently
available from the ground truth stations during
the days that the samples were collected.
The mean PM2:5 values, as given by the reference
stations, are 5:58 2:25 mg=m3 for the residential
site and 6:34 1:26 mg=m3 for the
industrial site. The differences between the reference
stations mostly result from differences in
the deployment location, with the reference station
closest to the industrial site being located in
a more densely populated area than the reference
station closest to the residential area. In
both cases, the mean values are small and correspond
to normal levels of background pollution.
For the residential location, the reference lines
in Figure 3 shows that the reference measurements
closely match the values in the experiments.
In contrast, the measurements from the
industrial site deviate and contain higher concentrations
than those from the reference station.
The higher concentrations are in line with
the higher degree of pollutants, as also shown
by the statistics of the pollutant concentrations.
The difference to reference values indicates that
the high pollutant concentrations are heavily
localized, and the pollutants get dispersed over
a larger area, thus resulting in only a small
increase within a single location.
The results highlight both that UAV measurements
are sufficiently accurate for pollution
monitoring and that they offer additional information
that environmental stations or other
existing solutions are likely to miss. First, the
results for the residential area, where pollution
levels generally are small, indicate that the UAV
measurements are largely in line with those
obtained from the fixed environmental stations.
The accuracy of the sensors has been separately
verified in laboratory conditions, and
thus the result merely confirms that the measurements
produce meaningful insights also
when deployed in the wild. Second, the emissions
from the industrial site were not observable
in the reference station measurements due
to the reference station being distant from the
site and the wind-patterns prevailing at the time
(low wind speed and in the opposite direction
as the reference station). Reference stations are
likely to capture only parts of the emissions
January/February 2023
when the wind and weather conditions align
with the dispersion direction. City-scale UAV
monitoring increases the scale of monitoring
and fills in the gaps in the measurements to
help understand dispersion and potential health
effects associated with it regardless of the
weather conditions.
DISCUSSION
Benefits to Stakeholders and Applications
Municipal authorities and public transportation
providers can assess the dispersion and distribution
of pollutants in detail, offering insights
into the health effects of pollutants, and a way to
monitor the effectiveness of clean air initiatives.
Industry can use vertical air pollution profiles to
assess their own pollution levels, e.g., compliance
with environmental regulations or the
potential of emission-offsetting operations. Similarly,
vertical profiles captured at ports or airports
help to understand how pollutants
resulting from passenger and freight transport
are dispersed within the city. Finally, city-scale
3D pollution monitoring supports scientific studies
and innovative applications, e.g., UAVs are
useful in modeling pollutant dispersion caused
by wildfires and other events.
City-Scale UAV Deployment
Ensuring adequate coverage of pollutant
information requires multiple UAVs to operate
simultaneously at different parts of the city. UAV
intercommunication using short-range communications
can improve cooperation and better
localization can reduce collisions, whereas stateof-the-art
mission planning solutions can be
extended to consider the vertical column of air
quality when sampling data. However, massive
city-scale deployments also require connectivity
to centralized stations where operators can
interpret and schedule simultaneous explorations.
Emerging 5G/6G networks provide the
backbone to achieve the vision.
Regulations and Other Challenges
UAV operations have the potential to be disruptive
and cause damage to transport and
other urban functions. This is resulting in UAV
operations becoming increasingly regulated. For
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IEEE Consumer Electronics Magazine - January/February 2023

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