1. Air Pollution and Health Sheryl Magzamen MESA-Air Pollution Study Presentation for Environmental Studies 100 University of Washington February 25, 2011

2. The NPR “reading” about budget cuts and diesel fumes focused on 1. 1. Power plants 2. 2. Generators 3. 3. Trucks 4. 4. School buses

3. Air pollution and health: overview Air pollution and health: overview Nuts and bolts of epidemiology Nuts and bolts of epidemiology Asthma and Air Pollution Asthma and Air Pollution Studies in schools Studies in schools Correlation v. Causation Correlation v. Causation Three “natural” experiments Three “natural” experiments Exposure Assessment Exposure Assessment Putting it all together Putting it all together Today’s Presentation

4. Health Effects: Air Pollution Map courtesy of WHO

5. Health Effects: Air Pollution WHO estimates 3 million premature deaths/yr attributable to air pollution Developing world, ~90% attributable to indoor air pollution 800,000 deaths attributed to outdoor air pollution (Cohen et al. 2005) 1.2% of all deaths globally United States: 20,000 premature deaths/year attributable to air pollution Aggravated respiratory disease Exacerbates cardiovascular disease Increases in hospital admissions, emergency department visits, and restricted activity days

6. Sources of Air Pollution Source: Vallero 2008

7. Sources of Air Pollution Source: EPA Annual VMT, United States (Source: Wall Street Journal)

8. Traffic Related Air Pollution HC CO CO 2 NO x 4-stroke cycle2-stroke cycleDiesel HC CO CO 2 NO x PM SO x PM CO 2 NO x Source: Vallero 2008

9. Image courtesy of the EPA Traffic Related Air Pollution

11. Epidemiology is… 1. The branch of philosophy concerned with the nature and scope of knowledge 2. The study of the history of words, their form and meaning 3. The scientific study of insects 4. The study of the distribution and determinants of disease in a population 5. The branch of medicine dealing with skin and its diseases

12. Health Outcome Exposure (descriptive)(analytic) General Epidemiologic Model

13. Air Pollution Epidemiology Where did I put that donut ? Epidemiology focuses on the presence and magnitude of the exposure effects on health outcomes

14. Epidemiologic Outcomes Morbidity Symptoms Symptoms Exacerbations Exacerbations Health care events (i.e. hospitalizations, emergency department visits) Health care events (i.e. hospitalizations, emergency department visits) Limitations in activity Limitations in activity Changes in physiologic measurements Changes in physiologic measurementsMortalityDeath

15. Asthma Outcomes Morbidity Wheeze, trouble sleeping Wheeze, trouble sleeping Use of inhaler Use of inhaler Unplanned health care use Unplanned health care use School/work absence School/work absence Impacts on quality of life Impacts on quality of life Lung function Lung functionMortality Very rare (~5000 cases/year US) Subjective measures (patient reports), objective measures (physiologic measures, administrative data)

16. IncidencePrevalence Incidence is used to understand etiology, or why the disease occurs; prevalence is used often for planning Epidemiologic Measures

17. In the McConnell et al. paper, what health outcome was measured? 1. 1. Prevalence of asthma cases 2. 2. Incidence of asthma cases 3. 3. Incidence of asthma hospitalizations 4. 4. Prevalence of heart attacks

18. Oakland Kicks Asthma Asthma surveillance and intervention program Students complete a brief, in-class asthma survey Students identified as “current asthma” are eligible for intervention(s)

21. Air Pollution and Asthma Table 1. Demographic characteristics of cohort by quartile of NO2 exposure Q1 6.13 - 16.14 μg∙m -3 (n= 186) Q2 16.14 – 17.13 μg∙m -3 (n=202) Q3 17.14 – 18.13 μg∙m -3 (n=229) Q4 18.14 – 24.10 μg∙m - 3 (n=188) chisq Race/Ethnicity A/PI10.28.913.512.80.41 Black41.949.042.446.30.42 Latino16.119.814.016.50.44 White10.20.52.64.3 <0.0001 NatAm00.5000.39 Mixed9.17.99.29.00.96 Other4.88.48.33.70.12

22. Air Pollution and Asthma Comparing the students in the highest NO 2 exposure group to the lowest NO 2 exposure group, we found: Students in the highest exposure group were 60% more likely to have trouble sleeping due to asthma compared to the low group Students in the highest group were 4 times as likely to have an emergency department visit for asthma compared to the low group Students in the highest group were 60% more likely to have trouble completing a sentence due to wheeze compared to the lowest group

23. Observation v. Experiment How do we distinguish correlation from causation?

24. Correlation v. Causation Football and the stock market Football and the stock market : If an old AFL (now AFC) wins the Superbowl, the stock market will be down. But…if winner is--like Green Bay--from the old NFL (now NFC), the market will be up. Has been on the money 33 of 41 years (80% success rate) Between 1967 and 1997, it was right 28 out of 31 times (better than 90%!)

25. Causality in Controlled Experiments Randomize Adolescents w/ Asthma dx to be… <500ft from Freeway? YES NO Emergency Care Utilization? YNNY

26. Causality in Controlled Experiments Image courtesy of Environmental Health Perspectives

27. Observation v. Experiment 1952 London Smog (photo courtesy of BBC) 1948 Donora Smog (photo courtesy of The Allegheny Front) 1930 Meuse Valley Smog (photo courtesy of Fluoride Action Network) Acute Air Pollution Episodes

28. Observation v. Experiment

29. Causal Thinking: Natural Experiments

30. Pollution in the Utah Valley Pope (1989): Compared number of childhood and adult respiratory events: During closure of a steel mill After reopening of the mill Rationale: When in operation, the steel mill produced about 80% of the coarse particles in the area, 95% of sulfur oxides, 98% of nitrogen oxides, and 82% of carbon monoxide.

31. Pollution in the Utah Valley Health findings: Children’s hospitalizations for respiratory diseases (asthma and bronchitis) were 2 – 3 times higher for the winter the mill was open compared to the winter the mill was closed. Stronger for children, though effects in adults still found

32. Summer Camp Studies Children tend to spend more time outside over the summer Due to meteorological conditions, ozone levels are generally highest in summer months Change in health with greater ozone exposure?

33. Summer Camp Studies Tested lung function on non-asthmatic children every afternoon in various US/Canadian summer camps Obtained daily ozone readings for each day lung function was measured Negative relationship between daily ozone measures and FEV1 (lung function) Series of six studies conducted in US and Canada that examined lung function and ozone exposure (Kinney et al. 1996)

34. German Reunification Major improvements in air pollution levels in East Germany 1 – 3 years post reunification (1990) Findings: Higher prevalence of non-asthmatic respiratory illness for children growing up in areas of higher of TSP and SO 2 Reductions in prevalence of bronchitis, colds and infections decreased in parallel with reduction of TSP and SO 2 in 1992 – 93 and 1995 – 96. Heinrich et al. 2000

35. My house ¼ mi What are important considerations in estimation? What are other considerations?

36. Exposure Assessment Many studies use proxy variables to estimate exposure to ambient air pollution <=150 m = “Exposed” >150 m = “Not Exposed”

37. Exposure Assessment

42. What are other important considerations when trying to estimate exposure? Exposure Assessment Courtesy of NASA Meteorology

43. What are other important considerations when trying to estimate exposure? Exposure Assessment Time activity patterns

44. Does Epidemiology Have All the Answers? Taubes: Do We Really Know What Makes Us Healthy? Epidemiology: Do We Really Know What Makes Us Unhealthy?

45. What was identified in Taubes 2007 as the type of study that can get us closest to an answer on causation? 1. 1. Cohort study 2. 2. Case-control study 3. 3. Randomized- controlled trial 4. 4. Nurses’ Health Study

46. Why does the US Men’s National Soccer team have difficulty winning in Mexico? 1. 1. Really, really intimidating crowd 2. 2. Playing at altitude (Mexico City: 7349 ft. above sea level) 3. 3. Pollution levels in Mexico City 4. 4. It’s hot there 5. 5. We are just an inferior soccer nation

47. In science, we often take a reductionist viewpoint Looking for the “smoking gun” Air pollution is not one exposure! Many different compounds, concentrations that co-exist Remember: ozone = sunlight + NOx + VOC Disease = interaction between many factors: Environment Genetics Behavior Putting it all together

48. Epidemiology is the study of the distribution and determinants of disease in human populations Air pollution is implicated in both chronic disease morbidity and mortality Air pollution epidemiology has several important challenges How do we capture the relevant exposure? For whom do we want to make scientific inference? No one study will give us all the answers: look at the body of research as a whole Conclusion

49. Thank You Feel free to contact me at: slm1@uw.edu