Nitrogen dioxide (NO2) is produced by high temperature processes in air. In an urban environment, the main sources of nitrogen dioxide are from the exhaust products of combustion engines (cars and trucks) and industrial processes. The US EPA standard for NO2 is 100ppb averaged over an hour and 53 ppb averaged over a year. The Cully NO2 survey we conducted shows that NO2 levels in the region we surveyed are well below the EPA standard.
We did not expect to see NO2 levels above the EPA standard. The Portland area, like all American cities, have been in compliance with EPA standards for many years. However, since NO2 is relatively easy to measure compared to many other pollutants, it has been used over the past decade as a marker of the spatial extent of combustion related air pollution. Combustion related exhaust contains nitrogen oxides, particulate matter, toxic hydrocarbon, etc. The Cully NO2 study shows where there are regions of higher influence of combustion related exhaust than others. In particular, there is elevated NO2 along the Columbia Blvd. corridor and along I-205. During the sampling period (March 15-27, 2017), the prevailing winds were mainly from the south and east. In the summer, the winds are generally from the north and west in this area.
5/25/17 LAG
