The Bent Creek data also reflects people s daily activities. Also, when people drive to work each day they release nitrogen oxides from the tailpipes of their automobiles. The large amount of nitrogen oxides released early in the day contributes to recipe that forms ozone. 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.