Urban pollutants O3 and NO2 can nitrate proteins in the atmosphere by forming 3-nitrotyrosine, and it has been shown that allergies can be heightened by nitrated proteins. The optical properties of nitrated proteins have also been shown to change upon nitration, and these reactions could influence how fluorescence is used to detect bioparticles threat agents. Here we developed a new procedure to selectively detect nitrated Amb-a1 protein using a sandwich ELISA protocol. Second, we extracted measurable amounts of protein from pollen spiked onto filters. A lower limit of tilde 1 percent of protein mass extracted from Ambrosia artemisiifolia (ragweed) pollen was the highly allergenic Amba1 protein. These efforts culminated in a proof-of-concept study to investigate whether polluted air could sufficiently nitrate pollen proteins. We exposed ragweed pollen and Amb-a1 to mildly polluted outdoor air (22 ppb NO2, 49 ppb O3) for 7 days. Using the sandwich ELISA we show that tilde 1 percent of protein mass extracted from spiked filters of pollen was Amb-a1 nitrated by ambient air. This suggests that atmospheric reactions may be able to nitrate anemophilous pollen protein sufficiently to influence human allergies. Lastly, we showed dramatic reduction in fluorescence intensity of four proteins nitrated by an aqueous nitration reaction.