An increase in the level of nitrogen dioxide and a decrease in the level of ground-level ozone occurs.
Step-by-step explanation:
Ozone gas is normally found in stratosphere, it protects us from solar radiation. Under certain circumstances, it can be formed on the ground level.
Conditions that have to be met in order for this to happen are existing of nitrogen oxides and volatile organic compounds and their reaction catalyzed by heat and light.
During dark, cold and cloudy days, due to the lack of heat and light from the Sun, formation of ozone will be decreased.
Also, this will enable building up of nitrogen dioxide, due to the same reason, leading to increased concentration.