The combination of a favorable environment and high nitrogen oxide emissions makes high ozone concentrations during the day. Conversely, later in the day, many people drive home from work and electrical demand remains high on the hot days thus there are still large amounts of nitrogen oxides released into the atmosphere. Solar radiation declines until sunset and the temperature also decreases. The nitrogen oxide emissions then serve an interesting role due to their abundance. Instead of contributing to ozone formation, the nitrogen oxides react with the ozone present in the atmosphere and cause a reduction of ozone concentrations during the nighttime.
Winds can carry ozone formed in urban areas long distances to surrounding rural areas.
Much of the ozone pollution at high elevations in the mountains of Western North Carolina is transported by winds from other states. Consequently, people and vegetation at higher elevations are exposed to more ozone then people and vegetation at low elevations. Effect on Plants Ozone effects on plants are most pronounced when soil moisture and nutrients are adequate and ozone concentrations are high. Under good soil moisture and nutrient conditions the ozone will enter through openings into the leaf and damage the cells that produce the food for the plants. Once the ozone is absorbed into the leaf, some plants spend energy to produce bio-chemicals that can neutralize a toxic effect from the ozone.