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Asthma and Air Pollution: What We Know – and Some Things We Don’t Know

Asthma and Air Pollution: What We Know – and Some Things We Don’t Know. Mary Ellen Gordian, MD, MPH. Particulates Exacerbate Asthma. Particulates: dust particles too small to see but can be inhaled

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Asthma and Air Pollution: What We Know – and Some Things We Don’t Know

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  1. Asthma and Air Pollution:What We Know – and Some Things We Don’t Know Mary Ellen Gordian, MD, MPH

  2. Particulates Exacerbate Asthma • Particulates: dust particles too small to see but can be inhaled • Inhalable size particles PM10 if less than 10 microns in diameter, PM2.5 if less than 2.5 microns • Exacerbate: make asthma symptoms worse

  3. Particles <10 microns but >2.5 microns “coarse fraction of PM10” Coarse fraction mostly from the earth, consists of molecules containing silica and aluminum Particles <2.5 microns called “fine fraction of PM10” Fine fraction usually produced by burning petroleum products or wood. Smoke contains carbon molecules Coarse Fraction versus Fine Fraction

  4. PM2.5 have been studied most extensively in the lower 48 • PM2.5 associated with increased risk of heart attacks and increased neonatal deaths • These very small particles from combustion sources can get into lungs & cross cell membranes • Can carry toxic chemical & biological substances into body

  5. In Alaska, Coarse Particles Predominate • In Anchorage, PM10 highly correlated with coarse particles but not fine particles • Health studies in Alaska show that PM10 (coarse fraction) aggravates asthma symptoms, increases doctor’s visits for asthma • School nurses give more asthma meds to children on high-particulate pollution days

  6. Doctor’s visits for asthma and particulate air pollution • Anchorage time-series analysis published in 1996 Environmental Health Perspectives • Used insurance data for state and city employees/dependents (14,000 persons) for 3 years • Showed increase of 2.5% in asthma visits for every 10 microgram/cubic meter increase in PM10

  7. Studies show that traffic makes asthma symptoms worse. • Children with asthma living close to busy roads hospitalized more often for asthma than children in less-congested areas • Children living near busy roads more likely to have reduced lung function • In Anchorage we showed that children living in high-traffic areas more likely to be diagnosed with asthma

  8. Why does traffic exacerbate and possibly cause asthma? • Traffic creates noise, which may increase anxiety • Traffic creates dust both from roads and engine exhaust; increasing both coarse and fine fraction • Traffic creates fumes from gasoline and diesel fumes

  9. What air toxics result from traffic? • Benzene, toluene, ethylbenzene and xylenes are products of gasoline • Formaldehyde & other aldehydes produced by burning gasoline • Polycyclic aromatic hydrocarbons (PAH) produced by burning fuel & found in cooked food

  10. There Are Few Studies On Air Toxics • Air toxics not regulated by Clean Air Act, not measured regularly • Measuring air toxics is expensive • Indoor air more likely to have higher concentrations of air toxics than outdoor air because products containing air toxics used in homes

  11. Indoor Air versus Outside Air • Indoor air more polluted than outdoor air • Cooking, cleaning products, off-gassing of materials, pets, people, and smoking all contribute to indoor air pollution • Energy efficient houses reduce the number of air exchanges • Heating can add to indoor air pollution

  12. Anchorage Indoor Air Study • Measured benzene, toluene, ethylbenzene and xylenes (BTEX) in over 500 homes • Rate of asthma diagnoses not related to BTEX, HOWEVER… • …odds ratio for severe asthma symptoms was 2.49 in households with >9ppb of benzene (after smoking & other confounders factored out)

  13. Can reducing indoor air pollution reduce asthma symptoms? • AHFC weatherization study to determine if improving homes could reduce asthma problems for children • Hooper Bay and Fairbanks participated • 3 children in Hooper Bay & 13 in Fairbanks examined, only Fairbanks children had follow-up • >30% initially had IgE >300 units

  14. Asthma symptoms showed improvement in follow-up • Follow-up IgE, FVC% predicted, and FEV1% predicated all improved after home mitigation, but did not reach statistical significance • Mean initial IgE 215.0; follow-up 172.7; p=0.08 on paired T-test • Mean initial FVC %pred.103; Follow-up FVC %pred. 111; paired T-test p=0.07 • Mean initial FEV1 %pred. 90; Follow-up FEV1 %pred. 96; paired T-test p= 0.07

  15. Activities to reduce indoor air pollution • Do not allow indoor smoking • Use exhaust fan when cooking • Do not store gasoline or gasoline engines in house or area sharing air space with house • Use materials certified free of aldehydes • Less carpet is easier to keep clean

  16. Bibliography Air Quality in Anchorage: (2000) A Summary of Air Monitoring Data and Trends (1980-1999) http://www.indicators.ak.org/Indicators/AirQualRept99.html Brunekreef B, Janssen NA, de Hartog J, Harssema H, Knape M, van Vliet P. (1997) Air pollution from truck traffic and lung function in children living near motorways. Epidemiology; 3:298-303. Gordian ME, Haneuse S, Wakefield J. (2006) An investigation of the association between traffic exposure and the diagnosis of asthma in children. J Expo Sci Environ Epidemiol. Jan;16(1):49-55. Gordian ME, Ozkaynak H, Xue J, Morris SS, Spengler JD. (1996) Particulate air pollution and respiratory disease in Anchorage, Alaska. Environ Health Perspect;104(3):290-7. Gordian ME, Choudhury AH PM10 and asthma medication in school children Arch Environ Health 2003 Jan;58(1):42-7

  17. Additional Bibliography Shima M, Nitta Y, Ando M, Adachi M. (2002) Effects of air pollution on the prevalence and incidence of asthma in children. Arch Environ Health; 57(6):529-35 Thompson AJ, Shields MD, Patterson CC. (2001)Acute asthma exacerbations and air pollutants in children living in Belfast, Northern Ireland. Arch Environ Health; 56(3):234-41 van Vliet P, Knape M, de Hartog J, Janssen N, Harssema H, Brunekreef B. (1997) Motor vehicle exhaust and chronic respiratory symptoms in children living near freeways. Environ Res;74(2):122-132 Edwards J, Walters S., Griffths RK. (1994) Hospital Admissions for Asthma in Preschool Children: Relationship to Major Roads in Birmingham, United Kingdom. Arch Environ Health; 49(4):223-7

  18. Bibliography (cont.) Arif AA, Shah SM. Association between personal exposure to volatile organic compounds and asthma among US adult population. Int Arch Occup Environ Health. 2007 Aug;80(8):711-9 Venn AJ, Lewis SA, Cooper M, Hubbard R, Britton J (2001) Living near a main road and the risk of wheezing illness in children. Am J Respir Crit Care Med. Dec 15; 164(12):2177-80 Ware JH, Spengler JD, Neas LM, Samet JM, Wagner GR, Coultas D et al.(1993). Respiratory and irritant health effects of ambient volatile organic compounds. Am J Epidem 137:1287-1301 Zmirou D, Gauvin S, Pin I, Momas I, Sahraoui F, etal Vesta investigators.( 2004) Traffic related air pollution and the incidence of childhood asthma: results of the Vesta case-control study. J Epidemiol Community Health; 58:18-23 Ciccone G, Forastiere F, Agabiti N, Biggeri A, Bisanti L, et al. (1998) Road traffic and adverse respiratory effects in children. SIDRIA Collaborative Group. Occup Environ Med.; 11:771-8

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