stylistic:tone, structural:expansion, structural:reformatting
Air pollution

In urban areas, the configuration of buildings can lead to exacerbated wind patterns and an uneven dispersion of pollutants. When the height of buildings surrounding a source of air pollution is increased, the size and occurrence of both "dead-zones" and "hotspots" were increased in areas where there were almost no pollutants and high concentrations of pollutants, respectively. Figure 6 depicts the progression of a Building F's height increasing from 0.0315 units in Case 1, to 0.2 units in Case 2, to 0.6 units in Case 3. This progression shows how as the height of Building F increases, the dispersion of pollutants decreases, but the concentration within the building cluster increases. The variation of velocity fields can be affected by the construction of new buildings as well, rather than solely the increase in height as shown in the figure. As urban centers continue to expand upward and outward, the present velocity fields will continue to trap polluted air close to the tall buildings within the city. Specifically within major cities, a majority of air pollution is derived from transportation, whether it be cars, trains, planes, or boats. As urban sprawl continues and pollutants continue to be emitted, the air pollutants will continue to be trapped within these urban centers. Different pollutants can be detrimental to human health in different ways. For example, particulate matter from vehicular exhaust and power generation can cause asthma, bronchitis, and cancer, while nitrogen dioxide from motor engine combustion processes can cause neurological disfunction and asphyxiation.