Pollen Effects on Asthma, Allergic Rhinitis and Finger Wound Emergency Department Visits Between 2000-2010 inBaltimore, Maryland
Mickey (Hsin) C. Wu, MPH1, Amir Sapkota, PhD2, John T. Braggio, PhD, MPH1
1Maryland Department of Health and Mental Hygiene, Baltimore, MD, 2University of Maryland School of Public Health, College Park, MD
Background Many factors contribute to respira-tory-allergic disease onset, especial-ly asthma1-7. Published studies havedemonstrated that pollen levels influ-ence the onset of a respiratory diseasesuch as asthma4, 6-7. Up to now pollen ef-fects on asthma have not been reportedfor the State of Maryland. To understandhow pollen quantity and type contributeto the onset of respiratory diseases thisstudy implemented these methodologi-cal improvements: 1) Use of 11 yearsof pollen readings from the only Nation-al Allergy Bureau (NAB) certified pollencounting station in Maryland. 2) Avail-ablity of 11 years of Emergency Depart-ment (ED) visits for asthma and aller-gic rhinitis, and a non-respiratory dis-ease control group composed of fingerwound injuries. 3) Evaluation of the dis-tance hypothesis for pollen effects onrespiratory disease ED visits. 4) Evalu-ation of ambient temperature on pollenlevels during the same 11 year peri-od. It was anticipated that: 1) Pollen-specific effects should be restricted toasthma and allergic rhinitis ED visits,and exclude finger wound injuries. 2)Ragweed pollen should be more aller-genic than tree or grass pollen. 3) Polleneffects on asthma and allergic rhinitisshould continue to decrease as the dis-tance between the pollen counting sta-tion and the patients’ county of resi-dence increases. 4) There should bea positive association between ambienttemperature and pollen level.
Methods1) Health Data: Asthma, ICD-9-CMcode of 493 (n=302,866); Allergic Rhini-
tis, ICD-9-CM code of 477 (n=56,598);Finger Wound Injuries, ICD-9-CM codeof 883 (n=152,607).
ED visits data were obtained from theMaryland Environmental Public HealthTracking Program. The original datasteward was the Maryland Health Ser-vices Cost Review Commission.
2) Pollen Data: National Allergy Bu-reau (NAB) certified pollen countingstation, Owings Mills, Maryland. Pollenreadings were recorded from Februarythrough October. An intermittent Ro-torod unit was used. It was positionedabout 30 ft. above the ground. Elevenyears of pollen grain readings wereavailable for tree, grass, weed and rag-weed. Please refer to Figure 1, Statemap, for location of NAB certified pollencounting station.
3) Temperature: Monthly temperaturereadings, in degrees Fahrenheit, wereobtained from Baltimore Washington In-ternational (BWI) Airport8. The lineardistance from BWI to the pollen count-ing station was 22.3 miles, based onGoogle Maps.
4) Confounders: The two con-founders controlled were ozone and finePM. The linear distance between thePadonia air monitoring station (Cock-eysville) and the pollen counting stationin Owings Mills was 14.2 miles, basedon Google Maps9. Figure 1 shows thelocation of the criteria air pollutant mon-itoring station.
Table 1: Total (Percent) ED visits for asth-ma (1st column), allergic rhinitis (2nd) andfinger wound injuries (3rd) and population(last) in the three distance groups.
Figure 1: Map shows locations for thepollen counting station in Owings Mills(red), BWI airport for temperature (blue)and Cockeysville for criteria air pollutantsin (yellow).
Maryland jurisdictions in three distancegroups shown in Table 1 and Figure 1: 1)0-10 miles: Baltimore, Baltimore City andHarford; 2) 11-20 miles: Carroll, QueenAnne's, Anne Arundel, Cecil, Kent andHoward; 3) 21-30 miles: Prince George'sand Montgomery.
Data AnalysesData analysis Steps: 1) Data were firstaggregated by county and month, thenconcatenated. 2) Linked files were ana-lyzed using Proc GENMOD in PC SAS9.3. 3) Poisson transformation and Neg-ative Binomial were used prior to theanalysis of the linked files10-11. 4) Alphawas set at p<0.05 for all analyses. 5)Three circles were created, each with aradius of 10 miles from the pollen count-ing station, to evaluate the pollen dis-tance hypothesis (see Table 1 and Fig-ure 1). 6) Correlation and partial correla-tion analyses were carried out betweenpollen and temperature.
Results
1) Pollen Effects on ED Visits: Asth-ma--Significant contribution for the 2ndquartiles for both weed (OR=1.18, 95%CI =1.09-1.28) and ragweed (OR=1.29,95% CI =1.14-1.47). Allergic rhini-tis--Significant contributions for the 3rdquartile of tree (OR=1.20, 95% CI=1.11-1.30) and grass (OR=2.01, 95%CI =1.80-2.23). Finger wounds--Signifi-cant results were not clearly discernible.But, the 2nd quartile for weed pollen(OR=1.11, 95% CI =1.06-1.16) was sig-nificant.
2) Odds Ratios (ORs) by Year,2001-2010 Relative to 2000 for Asth-ma, Allergic Rhinitis and FingerWound Injuries are Shown in Figure2:
Figure 2: ORs for the three groups from2001-2010, relative to 2000.
3) Distance Effects of Pollen: 0-10miles: asthma (OR=2.81, 95% CI=2.66-2.97); allergic rhinitis (OR=1.74,95% CI=1.65-1.84); finger wounds(OR=1.30, 95% CI=1.26-1.35). 11-20miles: asthma (OR=1.22, 95% CI=1.14-1.32); allergic rhinitis (OR=0.86,95% CI =0.80-0.92); finger wounds(OR=1.28, 95% CI =1.23-1.33).
4) Climate Change Proxy Measures:All pollen types were significantly cor-related with temperature in unadjust-
ed and adjusted analyses. Shared vari-ance (r2) increased in the adjusted anal-yses, after the confounding effects ofthe two criteria air pollutants, fine PMand ozone, were controlled (see Table2).
Table 2: Unadjusted and adjusted correla-tions between pollen and temperature.
Discussion To our knowledge, this is the firststudy on the effects of pollen on arespiratory disease for Baltimore City/County or Maryland. Pollen does con-tribute to significant increases in asthmaand allergic rhinitis ED visits in a waythat is qualitatively different from the ef-fects of pollen on finger wound injuries.Ragweed pollen produced greater al-lergenic effects on asthma and allergicrhinitis than tree or grass pollen. Thedistance hypothesis analysis demon-strated a stronger contribution of pollenwithin the 0-10 miles than 11-20 miles,relative to the control distance of 21-30miles. These results offer evidence thatpollen effects are not uniform over longdistances, as some authors have as-sumed5-7.
An unexpected outcome was thenon-linear relationship between pollenand finger wound injuries. We selectedfinger wound injuries because pollen ef-fects are not mediated through a res-piratory mechanism. But, this complex,and qualitatively different relationshipbetween pollen and finger wound in-
juries, suggests that pollen can indirect-ly contribute to finger wound injuries inways that are not yet fully understood,e.g., disorientation and inattention asprecursors to a finger injury.
Even though this study includedseveral methodological improvements,these results should be intrepreted withcaution. These analyses were complet-ed on aggregated observations. Wedo not know if the results will be thesame as would be obtained if individualrecords were used in the analyses.
We found that temperature, pollenand respiratory ED visits were higherat the end than at the beginning of the11 year data analysis window. Undersome circumstances it may be possibleto use 11 years of pollen and temper-ature readings as a proxy for climatechange effects.
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Footnotes1) These results were based on thework completed by the first author as
part of her MPH thesis at the Universi-ty of Maryland School of Public Health,College Park.
2) The work reported in this posterwas supported by Cooperative Agree-ment Number 5U38EH000944-03 fromthe Centers for Disease Control andPrevention and awarded to the Mary-land Department of Health and Men-tal Hygiene, Baltimore. Its contents aresolely the responsibility of the authorsand do not necessarily represent the of-ficial views of the Centers for DiseaseControl and Prevention.
3) This poster was presented at the2014 Council of State and TerritorialEpidemiologists Conference, Nashville,TN, June 22-26.
ContactMickey (Hsin) C. Wu, MPH
Environmental Health Bureau
Maryland Department of Health
and Mental Hygiene
201 West Preston Street, 4th Floor
Baltimore, MD 21201-230
Telephone: 410-767-1665
E-mail: [email protected]
