Lab Exercise: Environment and Health: Feeling the Changes

Patrick Callahan

Summary

In this lab, students learn how ozone air pollution affects human health using ozone simulation files. Students assess geographic (urban versus rural) and temporal (1990s versus 2050s summers) variations. Students perform health risk assessments to calculate ozone-related mortality, employing health risk assessment models. Through this lab students will learn to evaluate the mitigating environmental factors that impact human health.

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Learning Goals

Students will learn the following:

- To apply a health risk assessment model to ozone simulations of current versus future conditions in the New York metropolitan region

- To employ health risk assessment models to examine how climate change effects on local ozone concentrations can impact ozone-related mortality

Context for Use

The format suggested for this lesson is a lab-based course. Since it requires no laboratory equipment, the class size can range from a small student seminar to a medium sized lecture hall. The only mitigating factor related to class size is the necessity for each student (or perhaps pairs if the instructor elects to make the lab report a paired activity) to have a computer terminal. The class does not need to have a SmartBoard or LCD projector, since the lab work will be conducted at individual computers, but access to multimedia equipment is preferred. This lab does require some lecture set-up: a description of ozone and its relationship to human health, ozone simulation models, and application of the models. See "Description and Teaching Materials" below for link to the source lab.

Description and Teaching Materials

The structure and primary components of this lab lesson is sourced from Columbia University's fall 2007 Earth Environmental Systems Climate (EESC) lab "Climate and Health." It's important that students understand what ozone is and the role it plays in our troposphere, thus, climate change. Therefore, it's suggested that the lab incorporate a brief lecture. Here are a few points (from the summary of the lab Climate and Health)

Ozone is a powerful oxidizing agent and lung irritant, and numerous studies have linked ozone exposures to increases in the number of admissions or emergency room visits for respiratory illnesses, diminished lung function, and exacerbation of asthma symptoms (Brunkereef and Holgate, 2002, Kinney 1999). In 2006 it was estimated that more than 100 million Americans live in areas that exceed the EPA's health-based ozone standard and that even low levels of tropospheric ozone are associated with increased risk of premature mortality (Bell et al. 2006).

Climate change can influence the concentration and distribution of air pollutants through numerous processes, including the modification of biogenic emissions, the change of chemical reaction rates, mixed-layer heights that affect vertical mixing of pollutants, and modifications of synoptic flow patterns that manage pollutant transport. Changing meteorological conditions (temperature) impact ozone conditions. Tropospheric ozone is a secondary pollutant (not directly emitted) that is formed via complex chemical reactions involving nitrogen oxides, reactive hydrocarbons (also known as VOCs), and sunlight.

Air quality simulations compared with observed ozone data are being used to project future ozone concentrations across the New York metropolitan area. This lab uses these ozone simulation files to evaluate how climate change effects local ozone concentrations and impact human health.

Lab directions:

First open up lab by engaging students in a brief discussion. Ask students to compare and contrast the temperature differences between the college campus and where they come from. Note regional differences and demographic (urban versus rural). Prompt students to briefly discuss these differences and the way(s) they impact climate.

Part 1 - Geographic Variations in Ozone

  1. Open up Excel file containing ozone data and go to a worksheet titled "1-hr 1993"and compute some basic statistics (mean, minimum, maximum, and standard deviation) for daily summer 1-hr ozone concentrations in an urban county (e.g. Manhattan) versus a non-urban county (e.g. Dutchess County)
  2. Which county has the lower mean summer concentration? Lower maximum? Taking into consideration what students understand about different sources and types of ozone precursor emissions, can they propose reasons why there might be a different in rural versus urban concentrations?
  3. Plot the time-series of daily ozone concentrations for the two counties on the same axes, to get a visual comparison of the time trends in daily 1-hr maximum ozone concentrations over the course of a typical summer of the 1990s.
  4. Now repeat steps 2-5 for the same two counties, but use ozone concentrations on the worksheet titled "1-hr 2053" (a look at the future projections from CMAQ and simulations over the course of a typical summer of the 2050s.
  5. Which county has a lower mean summer concentration? Lower maximum? Have the comparative relationships between 2 urban versus non-urban counties changed over time?

Part 2 Temporal Variations in Ozone

  1. Open up the "1990s_v_2050s_31 County Average" worksheet; compute the descriptive statistics (the mean, minimum, maximum, and standard deviation) for the 1990s versus 2050s summers, averaged across the NY metro region, and plot the time-series.
  2. Which decade has the lower mean summer concentration? Lower standard deviation? Lower maximum?

Part 3 Health Risk Assessment: Calculating Ozone-Related Mortality

In public health there are two widely used modeling methods that can be applied to evaluate potential climate-health links. One method includes the epidemiological analyses, which use empirical data on environmental exposures and human health responses to derive models that estimate the relationship between a past or present environmental exposure and potentially associated health outcomes.

A second method, health risk assessment, is a way to project future risks to health from estimated changes in environmental exposures.

(Refer to "Climate and Health" Lab, EESC 2100 Fall 2007, for breakdown of health risk assessment instructions for calculation)

Geographic and Temporal Variations in Ozone-Related Mortality

  1. In spreadsheet Ozone_DailyMax_1990s_2050s open the worksheet "Health RA Formula" on tab 16; in cell G7, review the formula for calculating the 1990s county-specific summer ozone-related mortality burden, given the CMAQ-simulated mean daily 1-hr maximum ozone concentrations for that decade's summers.
  2. Copy that formula through cell G37 to evaluate the other 31 counties for the 1990s. Calculate the regional total number of ozone-related deaths in a typical 1990s summer. What is the range of county-specific values for summer ozone-related deaths (the minimum value and the maximum value from the individual counties)? Which types of counties show the highest numbers of ozone-related deaths? What are the primary factors affecting these totals?
  3. Repeat steps 8-9,but for "A2" 2050s, and apply similar steps in column L; answer the same questions.
  4. In column M, calculate the difference between the estimated mortality in the 1990s versus the student projection of mortality in the A2 2050s. Copy the formula in M7 down through cell M37. Total the differences calculated for each county to sum the aggregated regional change in summer ozone related mortality under a changing climate. What is the percentage change across the entire region by the 2050s, using the 1990s as the denominator (for example, M7/G7)? Looking at the individual county values, in what country is the percentage increase greatest? What is the range of absolute values, and in which counties are the absolute numbers greatest and least?
  5. Are the aggregated regional changes in ozone-related mortality different from what was expected? If so, describe and propose one possible reason.

Questions to consider for lab report (see previous labs for instructions) - review in class

  • What types of regional differences do you see in the projected current versus future summertime ozone-related mortality?
  • In the future, if you were to propose an improved health risk assessment model system, what types of data would you seek on human exposures to ground-level ozone? What types of data could help you evaluate geographic differences in human health vulnerabilities? What types of data would you seek to construct alternative, region-specific projections of potential ozone concentrations over the next 50 years?
  • What are some of the sources of uncertainty in the ozone-related risk assessment?
  • Do you think the results of an ozone health related assessment such as this would be useful for local policy makers, regulators, or the public? If so, with what audience or groups?

Below are the links for source material and resources:

· EESC course page (for Greenhouse lecture notes): https://courseworks.columbia.edu/

· EESC Fall 2007 course page: http://eesc.columbia.edu/courses/ees/climate/syllabus.html

Handouts and Directions:

· Lab instructions (and data)

· Health risk assessment calculation instructions

Equipment/Supplies:

Data Lab

· Computer lab or moveable laptops with Internet access and Excel.

· LCD projector

· Handouts - lab and calculation instructions

· "Writing a Lab Report" (may have already been disseminated)

Environment and Health
Word version of the module
5_CM_EnvHealth.doc

Teaching Notes and Tips

Instructors/TAs may find it useful to refer to lecture notes from the following two lectures:

- Greenhouse gases (updates forthcoming for this public site): http://eesc.columbia.edu/courses/ees/climate/syllabus.html

- Climate and Health lab, summary: http://eesc.columbia.edu/courses/ees/climate/syllabus.html

Assessment

Students summarize their findings in a lab report.

References and Resources

- Greenhouse gases (updates forthcoming for this public site): http://eesc.columbia.edu/courses/ees/climate/syllabus.html

- Climate and Health lab, summary: http://eesc.columbia.edu/courses/ees/climate/syllabus.html