Noise pollution exposure is known to be associated with stress, raised blood pressure, memory loss, nervousness and depression.
Congested traffic is associated with stress and aggression, even domestic violence.
Air pollution is associated with perceived annoyance, not to mention all manner of medical conditions that have (IMO) obvious mood implications (COPD can be a real downer).
As a matter of opinion it seems obvious to me that a space designed for cars is not as comfortable to people as a space designed for people. As a matter of statistics, there are a lot of associations between motor traffic and poor mood, and illnesses with mood implications.