Maryland Department of Health
Environmental Health

Pollen Indicator

Pollen Indicator for Baltimore (Owings Mills), Maryland National Allergy Bureau (NAB) Certified Pollen Counting Station: 1997-2012 Daily Pollen Data Recorded During the Pollen Season (February through October)

Pollen:  In Maryland and in other states in the mid-Atlantic region pollen spores are produced by different sources that include trees in late winter and spring, different types of grasses in spring and summer and various weed types in late summer and fall of each year.  As pollen spore counts increase more people develop allergic reactions.   Ragweed is a known allergen; it takes fewer ragweed pollen spores to produce respiratory allergic reactions than are needed to produce the same respiratory allergic reaction with tree pollen.  Pollen has been shown to contribute to missed school and work days, development of hay fever, also known as allergic rhinitis, and the occurrence of more asthma and allergic rhinitis emergency department visits and inpatient hospitalizations. 

Pollen Counting Station: In Maryland there is one National Allergy Bureau (NAB) certified pollen counting station in Owings Mills (Baltimore), Maryland.  The pollen counts from the Baltimore NAB pollen counting station are available from the Maryland Tracking Network (MTN) public and secure portals queries tabs from 1997 through 2012.  Pollen counts are temporally aggregated to month, season and year on the public site and also day and week on the secure Maryland tracking portal.  Users can access the queries utility to produce their own customized pollen table and graph.  Displayed pollen counts for total pollen, tree, grass, weed and ragweed are shown as log10 values to better see differences for the larger pollen counts for trees from the much smaller pollen counts for ragweed.  To avoid missing values when zero (0) counts a transformed to a log10 scale, a constant (1) was added to all daily pollen values.  The final pollen spore value shown is for log10 total pollen per cubic meter of air.   

Local and Regional Pollen Sources: The number and type of pollen spores found in outdoor air can come from the type of pollen produced locally by known and visually confirmed pollen producers, and from more distant locations.  Based on anecdotal reports, some pollen spores can travel long distances, up to several hundred miles.  Lighter pollen grains can be transported by the wind.  Pollen can be carried by birds and can attach itself on the surface of particulate matter particles, such as PM10, in the air. 

Pollen Levels: Several factors contribute to increases in pollen spores in the air we breathe.  As the pollen season starts earlier and lasts longer different pollen sources produce more pollen.  Increases in temperature and carbon dioxide also contribute to more pollen spores being produced.  Heat island effects that have been found in urban areas, such as downtown Baltimore and other larger cities in the United States, also contribute to the increased production of pollen spores.  The presence of weeds, especially ragweed in cities, result in the increased production of more allergic pollen.    

Pollen and Respiratory Disease: The surface of the pollen grain includes proteins that can produce allergic reactions in persons exposed to pollen.  Breathing air with many pollen spores or ragweed pollen will make it harder for a person with asthma to breathe.  Children and older persons are especially susceptible to the effects of pollen on the appearance of allergic-related respiratory diseases such as asthma attacks or allergic rhinitis.  

Pollen and Air Quality: Several years ago criteria air pollutants, primarily fine particulate matter and ozone, were considered more important in explaining the onset of respiratory diseases, such as asthma emergency department visits or inpatient hospitalizations than pollen.  In these studies pollen was often viewed as a confounder.  As interest in pollen has increased, primarily because of the effects of near term climate variability and/or the anticipated long term effects of climate change, recently completed studies are now starting to show that pollen can have a contributory and independent effect on the appearance of and increased severity of respiratory chronic diseases, especially asthma.  Initial research results on the contribution of both criteria air pollutants and pollen on the same respiratory disease outcome are now starting to show that on days when ozone or fine particulate matter levels are elevated the adverse health effects of pollen on asthma onset or possibly an allergic rhinitis reaction are worse than on days when the same pollen sources and levels are present but air quality is not as bad.   This synergistic effect, between pollen levels and increased ozone or fine particulate matter, is thought to occur through the same inflammatory response. 

Decreasing Pollen Effects: There are several things that can be done to mitigate the adverse health effects due to higher pollen levels.  Decreasing total pollen in the air and also controlling the abundance of more allergic pollen such as ragweed pollen can be accomplished by excluding undesirable pollen producers in newly built communities or in established neighborhoods.  This type of ecological approach to lowering total pollen spores in the air can be accomplished by changing the emphasis on the selection of trees, shrubs or other pollen sources in landscaping projects to the selection of trees, shrubs, plants and flowers based on the criteria of pollen producers that emit fewer pollen spores and less allergenic pollen types.  In established communities where landscaping changes cannot be made easily, residents can limit their exposure to pollen by spending less time outdoors, taking showers to remove pollen spores on the skin, hair and around the nose and mouth, and changing clothes.  Other pollen exposure control efforts can include closing windows and turning on the air conditioner when at home, and closing windows and turning on the air conditioner in the automobile.  In the home air filters can be used to remove pollen from indoor air.  Persons who have asthma should also avoid spending too much time outside when criteria air pollutants are elevated and the concentration of pollen is also higher.  Persons who experience breathing problems on days when pollen levels are high should consult their personal physician or another health care provider such as an allergist.

Pollen Indicator Measures: The 1997-2012 daily pollen readings from the Baltimore (Owings Mills), Maryland NAB pollen counting station were used as the only data source to compute the six pollen indicator measures developed by the Council of State and Territorial Epidemiologists (CSTE)/State Environmental Health Indicators Collaborative (CSTE) Asthma Work Group. Pollen indicator computation steps are described in each pollen section in the How-To Guide and summarized below in each indicator section .

Pollen Indicator Citation: The reference for this pollen indicator is the Template and How-To Guide developed by the CSTE/SEHIC Asthma Work Group for the CSTE/SEHIC Climate Change Work Group.  Some members of the CSTE/SEHIC Asthma Work Group are also part of the CSTE/SEHIC Climate Change Work Group.

Baltimore Pollen Data Source: Chesapeake Clinical Research, Inc., 7939 Honeygo Blvd. # 219, Baltimore, MD 21236.

 

The Pollen Indicators: