When: 1997, What: Tulsa Pollen

As can be seen in the graph, the concentration of pollen in the air was at its peak around early April in 1997. In Tulsa the concentration was just over 5,000 pollen grains per cubic meter of air. This peak understandably coincides with the spring season, and a good deal of this pollen is probably Quercus, or oak pollen. Other noteworthy peaks are in early January (winter pollen), mid February, and especially late summer/early fall when ragweed is rampant.