Climate change-mediated effects on the environment in may worsen the burden allergies in the Washington, DC, area, with significant health and economic impact, and amplifying feedbacks in the form of pharmaceutical use. Temperature change in our nation’s capital are changing the plant behavior in such a way to lengthen and increase pollen exposure for residents. Work is under way to understand the true impact of these changes in our cities, however, there is indirect evidence that changes in allergic disease are likely, and good evidence that increased allergic disease severity results in significant economic loss for communities.

1. Climate Change Impact on Health: Allergic Disease in
Washington, DC, USA
Climate Literacy: Navigating Climate Change Conversations
Climate change-mediated effects on the environment in may worsen the burden
allergies in the Washington, DC, area, with significant health and economic impact, and
amplifying feedbacks in the form of pharmaceutical use.
Temperature change in our nation’s capital are changing the plant behavior in such a
way to lengthen and increase pollen exposure for residents. Work is under way to
understand the true impact of these changes in our cities, however, there is indirect
evidence that changes in allergic disease are likely, and good evidence that increased
allergic disease severity results in significant economic loss for communities.
Increasing Temperature, Washington, DC
The average annual temperature has been increasing since 1871, along with decreased
precipitation (not shown) and decreased snowfall (not shown).
Average Annual Temperature Washington, DC , 1871-2012
64
y = 0.0346x - 10.448
60
56
52
48
1871
1918
1965
YEAR
2012

2. Change in plant behavior, Washington, DC
Cherry Trees will experience peak bloom 29 days sooner by 2080
Looking at the tree population in Washington, DC, shows that there has been gradual
advancing of first flowering, estimated to be 4.5 days from 1970 to 1999. An analysis
performed of one of the region’s most econimically important tree species, cherry trees,
predicts up to a 29 day acceleration in the timing of cherry blossoms by 2080 1, with a
peak bloom date of March 4. The current Washington, DC, cherry blossom festival runs
from March 20 - April 14.
Oak Trees (Quercus species)
The author has an interest in this species as a known precipitant of severe allergic
rhinitis and conjunctivities and even seasonal asthma. In 2013 there was a significant
spike in tree pollen count levels (2870 grains/cubic meter), the highest in 12 of the last
1
Chung U, Mack L, Yun JI, Kim S-H. Predicting the timing of cherry blossoms in Washington, DC and
Mid-Atlantic States in response to climate change. PloS one. 2011;6(11):e27439. Available at: http://
www.plosone.org/article/info:doi/10.1371/journal.pone.0027439#s1 [Accessed May 22, 2013].

3. 15 pollen seasons. In addition, 2012 saw a pollen count peak that occurred three weeks
earlier than normal (3/28/2012, expected 4/18/2012).23
The actual health impact of changing pollen behavior is under intense study through
programs sponsored by the US Environmental Protection Agency and beyond.45 In
some cases, and earlier peak may mean a season that ends earlier. On the other hand,
a higher peak may mean increased severity of symptoms. A study of Quercus species in
Spain showed, “Results indicate that under a doubled CO2 scenario at the end of the
21st century Quercus pollination season could start on average one month earlier and
airborne pollen concentrations will increase by 50% with respect to current levels, with
higher values in Mediterranean inland areas.”6
Negative Impact on Health and Related Losses
It is generally believed that increased pollen counts over longer periods of time will
increase sensitization (creation and building of the immune response that causes
allergic symptoms), allergic symptoms, and worsening of allergic airway disease.7 This
analysis focuses on allergy only, which by itself has significant impacts on health and
productivity. Well done studies of the impact of various chronic coniditions in the
workplace rank allergy higher than diabetes and cancer in overall costs to employers
2
Samenow J. Tree pollen spikes to highest level since 2010. The Washington Post. 2013. Available at:
http://www.washingtonpost.com/blogs/capital-weather-gang/wp/2013/04/19/tree-pollen-spikes-to-highestlevel-since-2010/ [Accessed June 16, 2013].
3
Samenow J. Worst of tree pollen season may be over. The Washington Post. 2013. Available at: http://
www.washingtonpost.com/blogs/capital-weather-gang/wp/2013/04/22/tree-pollen-may-have-peakedlower-levels-arriving/ [Accessed June 16, 2013].
4
US EPA ERC. Extramural Research - Global Change Research Program. Available at: http://
www.epa.gov/ncer/science/globalclimate/ [Accessed June 16, 2013].
5
US EPA ERC. Research Project Database | NCER | ORD | US EPA. Available at: http://cfpub.epa.gov/
ncer_abstracts/index.cfm/fuseaction/recipients.display/rfa_id/503/records_per_page/ALL [Accessed June
16, 2013].
6
García-Mozo H, Galán C, Jato V. Quercus pollen season dynamics in the Iberian peninsula: response to
meteorological parameters and possible consequences of climate change. Annals of Agricultural ….
2006. Available at: http://www.uco.es/aerobiologia/publicaciones/modelling/climate_change/
Quercus_AAEM_def.pdf [Accessed June 16, 2013].
7
Blando J, Bielory L, Nguyen V, Diaz R, Jeng HA. Anthropogenic Climate Change and Allergic Diseases.
Atmosphere. 2012;3(4):200–212. Available at: http://www.mdpi.com/2073-4433/3/1/200 [Accessed June
16, 2013].

4. due to lost productivity and absenteism, and much higher than asthma, due to the
number of people affected.8
Total Employer Costs /Employee/Condition/Year $USD - (Across All Employees)
$400.00
247
71
$300.00
246
271
32
266
159
$200.00
54
76
$100.00
23
75
91
$0
Hypertension
Diabetes
Medical
100
48
7
61
Cancer
54
Heart Disease Behavioral Health
Absence+STD
20
29
Allergy
9
19
Asthma
Presenteeism (Lost Productivity)
A typical regimen for the author during peak
season looks like this. The cost of the
medications themselves is added to the cost
of the time involved to administer them, in
addition to supplemental medical care that is
required for symptoms.
An Amplifying Feedback
The photograph below was taken at a local
drug store in Washington, DC, during the
2012 peak pollen season. It shows the
8
Goetzel RZ, Long SR, Ozminkowski RJ, et al. Health, Absence, Disability, and Presenteeism Cost
Estimates of Certain Physical and Mental Health Conditions Affecting U.S. Employers. Journal of
Occupational and Environmental Medicine. 2004;46(4):398–412. Available at: http://
content.wkhealth.com/linkback/openurl?sid=WKPTLP:landingpage&an=00043764-200404000-00013
[Accessed October 19, 2010].

5. cleaned out shelves of allergy relief medications. The demand for these medications,
stimulated by pollen in the atmosphere, in turn feeds back to the production and
transport system for these medications.
The manufacture of pharmaceuticals accounts for 14% of carbon dioxide production in
health care in the United States (21% in the UK)9 , and health care in the United States
is responsible for 8% of the carbon dioxide production in the United States.10 Therefore,
increased demand for medications and medical care increases the production of carbon
dioxide, which feeds back into the climate system.
Conclusion
As the climate system is sensitive to human perturbations, so is the human immune
system to the climate system, which reacts to changes in pollen counts with increased
and prolonged reactions to airborne allergens. Plant behavior is changing in the
Washington, DC area, which will create downstream effects on human health and
ultimately amplifying feedback on the climate system itself. While the current
Washington, DC sustainability plan links to a strategic plan for addressing asthma in the
District by managing air quality 11, it is unclear how the impact of allergic illnesses
resulting from changes in plant behavior can be mitigated in the future.
9
Harvie J, Schettler T, Mikkelsen L, Flora C. Common Drivers Common Solutions. 2011. Available at:
http://129.186.33.245/staff/cflora/Commondrivers.pdf [Accessed February 20, 2012].
10
Chung JW, Meltzer DO. Estimate of the Carbon Footprint of the US Health Care Sector. JAMA.
2009;302(18):1970–1972. Available at: http://jama.ama-assn.org [Accessed December 2, 2009].
11
Sustainable DC Plan | sustainable. Available at: http://sustainable.dc.gov/finalplan [Accessed June 16,
2013].