Comments to CASAC on Comments to CASAC on Draft #2 of the SO 2 Risk - - PowerPoint PPT Presentation

Comments to CASAC on Comments to CASAC on Draft #2 of the SO Draft #2 of the SO2

2 Risk and Exposure Assessment

Risk and Exposure Assessment

Public Comments Session Public Comments Session CASAC Meeting CASAC Meeting April 16-17, 2009 April 16-17, 2009

• Dr. Anne E. Smith, Ph.D.

Vice President Comments prepared on behalf of UARG

A Key Result Reported in REA: # Occurrences >100% sRaw from 5-Minute Exposures by Exposure Range

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Source: REA Draft 2, Figure 9-7(a), p. 275

• St. Louis, exercising asthmatics

Figure 9-7 (a) -- Replicated in Color & Zoomed In

000’s of Annual Occurrences

• f > 100% sRaw

180 160 140 120 100 80 60 40 20 “As is” AQ

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• St. Louis, exercising asthmatics

Current 99/50 99/100 99/150 99/200 99/250 98/200 Primary Std. > .5 ppm .45-.5 ppm .4-.45 ppm .35-.4 ppm .30-.35 ppm .25-.30 ppm .2-.25 ppm .15-.2 ppm .1-.15 ppm .05-.1 ppm < .05 ppm

Impacts Estimates Are Based on Logistic Dose- Response Curve that Assumes Zero Threshold

Median Percent with ≥ 100% sRaw response to 5-min exposures Source: REA Draft 2, Figure 9-2, p. 262

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Over 60% of the impacts at the Current Standard are due to 5-minute exposures below 0.1 ppm, which is less than half of the lowest observed response level.

29% 14% 8% 32% 17%

Over 60% of the impacts at the Current Standard are due to 5-minute exposures below 0.1 ppm, which is less than half of the lowest observed response level.

Percent of Estimated Impacts (at Current Standard) for Exposures on Different Parts of Dose-Response Curve

Median Percent Responding

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99.6% of the impacts for “As Is” air quality are due to exposures < 0.1 ppm.

1.4% 0.3% 0.1% 98.2% 0%

99.6% of the impacts for “As Is” air quality are due to exposures < 0.1 ppm.

Percent of Estimated Impacts (under “As Is” AQ) for Exposures on Different Parts of Dose-Response Curve

Median Percent Responding

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Sensitivity of Impacts to Alternative No-Effects Levels

• St. Louis, exercising asthmatics -- 000’s of Annual Occurrences of > 100% sRaw

180

Estimated effects 160 above 0.2 ppm

140

(lowest level of any detected effect):

120

Reproduced REA Figure 9-7(a)

100 180 80 160 60 140 40 120 20 100 “As Is” Current 99/50 99/100 99/150 99/200 99/250 98/200 80 AQ Primary Std. 60 180 160 40 140 20 120 “As Is” Current 99/50 99/100 99/150 99/200 99/250 98/200 AQ Primary 100 Std.

Estimated effects

80

above 0.4 ppm (lowest level of any

60

ATS-defined

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“adverse” effect 1/):

20 “As Is” Current 99/50 99/100 99/150 99/200 99/250 98/200 AQ Primary Std.

1/ ATS defines reversible lung function effects as “adverse” if they are statistically significant and accompanied by symptoms.

(“What Constitutes an Adverse Health Effect of Air Pollution?” Am J Respir Crit Care Med, Vol. 161, pp. 665-673.)

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Over 99% of the impacts are due to exposures below 0.1 ppm,

for every single alternative standard, including the Current Standard.

Comparable Results for Greene Co. Are Buried Deep in Appendix C of the REA

Greene Co., exercising asthmatics

Over 99% of the impacts are due to exposures below 0.1 ppm,

for every single alternative standard, including the Current Standard.

Source: REA Draft 2, Appendix C, Figure 4-5(a), p. 705

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The Uncertainty Analysis is Incomplete and Erroneous

Overestimate Unknown – because more severe asthmatics may be more likely to protect themselves with medication before exercising Missing uncertainty: Effect of medication among mild/moderate asthmatics in daily life Direction of bias: Overestimate Source: REA Draft 2, Table 9-10, p. 279

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