Pollen and Mold Summary 2011
Unlike the other pollutants for which RAPCA runs monitors, pollen and mold are
unregulated. There is no NAAQS (standard) for either pollen or mold. We
maintain the monitor due to our curiosity and the great public interest in these
biological pollutants. If we are not affected ourselves, we all know someone who's
miserable during the appropriate pollen and/or mold season.
Although unregulated per se, pollens and molds can contribute to the regulated
pollutant called particulate matter (PM), in particular, to PM10 and PM2.5. In most
cases, however, the pollen grains are even bigger than 10 microns and will tend to
be omitted by even the PM10 samplers. Molds can be small enough to be collected
in with the PM10 data, but in many cases the molds cluster together to form
aggregate particles which are also bigger than 10 microns.
Pollen
Pollen is the name for the small, spherical, or egg-shaped grains which are
produced by plants, flowers, weeds, grasses, and trees, and are necessary for plant
fertilization. When ingested or inhaled, pollen can trigger allergic reactions,
ranging from mild to severe, in about 40 million Americans.
There are two basic types of pollen, those that are carried by insects and those that
are carried by the wind. The latter type of pollen is the type which is most often the
culprit in allergies. Most flowers, such as roses and even goldenrod, produce
pollen which is carried by insects. In contrast, grasses, weeds and trees produce
small, light grains of pollen which are easily transported by the wind.
Hay fever, the body's allergic reaction to pollen, is the most common allergic
disease in the United States. Hay fever is characterized by nose, eye and throat
irritation, including sneezing, congestion, coughing and difficulty in breathing.
One in three hay fever sufferers develops asthma, a serious respiratory disease.
Mold
Mold spores are fungal reproductive cells of about the same size as pollen grains.
They can occur in various colors and shapes, such as round, spheroid, bananashaped, or tadpole-shaped. They can occur in enormous quantities, and at all times
of the year. Furthermore, they can cause allergic rhinitis (like hay fever), skin
reactions, and possibly asthma. During the fall harvest season incredible amounts
of molds can be stirred up, but well isolated from large populations, fortunately.
Mold spores can be found and generated at serious levels indoors, as well as out.
Stachybotrys, for example, has even been in the news when found in large
quantities in indoor air, and is described on Wikipedia:
http://en.wikipedia.org/wiki/Stachybotrys
RAPCA informs local radio and television stations as well as the newspaper. The
total counts for pollen and mold are also available daily on RAPCA's AirLine at
223-3222 (after 4:00 p.m.) and a more detailed report is available as well from
RAPCA's web page at http://www.rapca.org/daily/aqstats.htm. People with special
requests should contact RAPCA by phone.
The Monitoring Technique
Monday through Friday, RAPCA collects samples in the morning at our monitor
on the roof of the Dayton-Montgomery County Library on E. Third & St. Clair
(RAPCA Site # 46).
RAPCA uses a Burkard 7-day Recording Volumetric Spore Trap courtesy of the
American Academy of Allergy, Asthma, and Immunology (AAAAI) and their
National Allergy Bureau (NAB).
This sampling unit sucks particles inside where they run head on into a "greased"
microscope slide and are captured. The slide is slowly pulled past the intake orifice
so that readings by time of day can be developed, not that we have the time for this
maneuver!
After exposure, the slides are removed and stained with a red dye solution before
counting under an optical microscope. Separate speciation is made for numerous
pollen and mold types. Pollen species are then grouped into broader concentrations
for grass, trees, weeds, and "other”.
Because the intake flow rate is a constant value, the volume of air drawn in can be
computed. The pollen or mold counts from the microscope slide can then be
divided by the volume of air to give a concentration, the number of particles per
cubic meter (p/m3).
Our detailed data are sent to the American Academy of Allergy, Asthma, and
Immunology for inclusion in their daily web-based Pollen and Spore Reports. In
addition, we continue to report the data daily on our web site and send it to the
local media.
2011 Data
The summary tables for the pollen and mold data can be found in an Excel (.XLS)
spreadsheet at raw pollen & mold data, or as a simple HTML table, and the
table common names for pollen species may make things a bit more
understandable . If you need the day-by-day tables, please contact us, but first
look at the Air Quality Reports on our web site, www.rapca.org.
Pollen Discussion
Trees dominate our pollen readings, primarily in the early spring, starting in March
or even February. In 2011 the highest emitters were cupressaceae (cypress etc.),
morus (mulberry), quercus (oak), and carya (hickory & pecan). Cupressaceae
were by far the most predominant of the tree pollens, and tress are the most prolific
group, hugely higher than even ragweed.
Although there is a “grass season” between trees and weeds, grass concentrations
are much lower than either of the other two groups.
The following tables should help illustrate these points.
Year 2011 Pollen Graphs
The three main pollen seasons are shown in the 3 graphs below. First to arrive are
the tree pollens, then grasses, and finally flowers, weeds, etc. Trees dominate the
spring and ragweed dominates the fall. Notice the change in scale needed to show
the high tree pollen concentrations.
Trees, Grass, & Weeds
A look at the raw data tables will show you that most of the weed pollen is composed of ragweed
(ambrosia in the tables.) Traditionally, ragweed has peaked on Labor Day.
Ragweed levels in 2011 were nothing extraordinary, but supposing that you might want to
compare them to other years, we have prepared the graph below.
The 2011 data, indicated by the hatched light blue line, are the next to the lowest concentrations
of ragweed since the year 2000.
A similar cumulative total graph for all pollen, shown below, indicates that total pollen was right
in the middle in 2011 when compared to other years.
2011 Mold Discussion
The single highest daily concentration for any mold species was 8,906 for ascospores,
closely followed in second place by 8,550 for cladosporium,. Also, there were more
ascospores in total than there were cladospores. Both types occur on most days of the
year, and in some years cladosporium predominates. Relatively high were torula,
alternaria, and epicoccum.
Year 2011 Mold Graphs
Total Mold by Day
Comparisons of mold in 2011 with mold in other years:
Mod in 2011 doesn’t stand out comparatively speaking. In fact it’s on the low
side. Also, it seems to be much more uniform than in other years.
Please remember that the monitoring location changed from Centerville to Dayton
in mid-2001, so you will still be looking at "apples to oranges" comparisons.
Also, please bear in mind the large year-to-year variation you will see in the
following two graphs if you ever feel impelled to assert that “this year was an
unusually bad year for mold.”
An illustration of just how low the mold was in 2011:
What’s with the cumulative graphs, anyway? Well, traditional line graphs plot the mold
(or pollen or whatever) for each day for a year. There is one line for each year and they
tend to be very jagged and overlap a lot and are very hard to read if there are several
years involved.
A cumulative graph, on the other hand, does not jump up and down; it can only go
straight across or up. That’s because the first value is for Jan. 1, the second value is for
Jan. 1 + Jan. 2, the third is the sum of the first 3 days, etc. They are much easier to read,
yet still allow a good comparison of years. In the graph above, we can see that mold rose
much more quickly in 2010, although in 2008 it rose rapidly at the end of the season, and
put the overall mold for 2008 at the head of the pack.
2011, by the way, is at the bottom. It grew very slowly, and had the lowest total mold of
all 4 years.