Many shopping malls tend be located near highways as that makes them much more accessible and as they are often further away from a city due to lower real-estate prices. As they are located near a highway, would they also see more pollution?
Besides that question, Skanssi is also a well known shopping mall in Turku and provides a good test target. The previous test around Turku castle showed that when measuring while walking it is important to walk slowly. The data gather around Skanssi is the first good set of data, that is even interesting to look at.
The traffic density on the highway wasn’t very high, and it is thus not surprising that the air quality wasn’t affected. What did show in the air quality measuring (yellow and orange areas) is the constant car traffic going in and out of the Skanssi garage. That day the wind wasn’t blowing much, so it is not surprising that some air pollution accumulated in this area. The other areas around Skanssi do not see any traffic and are thus cleaner. If we measure Skanssi again, we should walk a bit further out and include at least the highway area.