Indicator # 4: Number and percent of days during the pollen season when pollen readings were categorically elevated (NAB categories of high or very high), by pollen source and species (if available from NAB or a pollen counting station as grasses, trees and weeds).

 Pollen Risk Communication Message: Pollen grains are released by trees in the spring, different types of grass in summer and a variety of weeds in fall.  Ragweed pollen is also released in the fall, but it is more allergenic than other pollen types.  Because of climate variability we now know that higher temperatures and more carbon dioxide result in increased pollen in the air.  Children and older adults who have asthma, allergic rhinitis or other respiratory diseases have more severe allergic reactions as total pollen grains in the air increase or when ragweed pollen is produced in the fall.  Pollen influenced allergic and respiratory reactions are even worse in the summer when ozone and/or fine particulates in the air are also higher.  Research has shown that higher pollen levels increase emergency department visits and inpatient hospitalizations due to asthma, hay fever and other respiratory diseases.  Prevention efforts can include seeing a health care provider before the start of the pollen season or when breathing problems become worse when pollen spores increase.  Persons can decrease their exposure to pollen by not going outdoor, staying in a home or automobile with the windows closed and the air conditioner on, taking a shower to remove pollen from around the nose and mouth, and changing clothes.  For more information about pollen and health see the MTN pollen indicator page.

• Determine the number of days in the pollen season in the calendar year when the readings were recorded in NAB’s high or very high category for each generic pollen source/species, if the latter is available.
• Divide by the number of days for which there are readings available for each pollen source/species (Note: This number will likely be different from measure # 3 as stations typically do not take readings every day during the pollen season).
• Compute the duration of the pollen season for any pollen (trees or grasses or weeds or ragweed) and for each pollen source separately.
• When finished, there should be five values. The first will be the duration of the pollen season in days for any pollen type. The second should be the duration of the pollen season in days for tree pollen. The third will be the duration of the pollen season in days for grass pollen. The fourth will be the duration of the pollen season in days for weed pollen. The fifth will be the duration of the pollen season in days for pollen.  The fifth will be the duration of the pollen season in days for ragweed pollen.
   

Table:

 Note: Pollen indicator measures # 1 through # 4 can be computed using daily pollen category values.  But, daily pollen counts, only available from a pollen counting station, are required to compute the next two pollen indicator measures, # 5 and # 6, below.