Heat-Related Mortality in Washington State: Past and Future The Washington Climate Change Impacts...

Heat-Related Mortality in Washington State: Past

and Future

The Washington Climate Change Impacts Assessment Conference

February 12, 2009

J. Elizabeth JacksonUniversity of Washington

Heat: Core Public Health Concern Heat waves linked with hundreds of deaths

in the United States annually

Chicago, 1995: estimated 700 deaths Europe, 2003: estimated 30,000 deaths UK, 2003: estimated 2,000 deaths



Heat waves projected to increase in frequency, duration and intensity




Heat-related mortality is likely under-reported




Heat-related mortality is likely under-reported

What about Washington State?

Thermal Stress Hyperthermia: the body cannot dissipate

heat absorbed from the environment (CDC, 2005)

Thermal Stress Hyperthermia: the body cannot dissipate

heat absorbed from the environment (CDC, 2005)

Vulnerable Groups Elderly Urban residents Those with chronic or mental illnesses The poor, the socially isolated Outdoor laborers

Other VulnerabilitiesMajor cities of Washington State are particularly at risk for high mortality during heat waves

Milder summers = less adaptation to heat Little residential air conditioning Heat Island Effect

Analytic Goals Establish historical relationship between

heat events and mortality (1980-2006)



Estimate future mortality due to heat, i.e., “excess deaths” (2025, 2045, 2085)



Estimate future mortality due to heat, i.e., “excess deaths” (2025, 2045, 2085)

Customize estimates for 4 study areas: Greater Seattle Area (King, Pierce, Snohomish) Spokane Tri-cities (Benton, Franklin) Yakima

Measuring Heat Events Humidex: combined effects of heat and

humidity

Heat event threshold: hottest 1% of all days (99th percentile humidex)

Heat Events: Counted the number of heat events and the duration of each heat event

Three climate change scenarios: high, moderate and low summer warming

Measuring Mortality Outcome: daily mortality rate, May-

September (= deaths/population)

Age groups: 45 and older; 65 and older; 85 and older

Causes of death All non-traumatic causes Circulatory, Cardiovascular, Respiratory (not

presented)

Method: Historical RelationshipRelative Risk of death during a heat event =

Mean Daily Mortality Rate(heat event)

Mean Daily Mortality Rate(non-event)

If RR > 1, then risk of death is greater during heat events

Method: Future Excess MortalityExcess deaths during future heat events are calculated from:

Baseline Mortality Rate Risk of death during heat event Future population Climate change

Mean Daily Mortality Rate(non-event) *(Relative Risk – 1)* Projected Population*Projected Heat Events

Baseline Population Parameters

Greater Seattle Area Eastern Washington

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

1980 2006 1980 2006

Yakima

Tri-cities

Spokane

Baseline Climate Parameters

Greater Seattle Area

Spokane Tri-Cities Yakima

Threshold, °F 92.5 100.6 100.9 95.9Mean annual number 1.7 1.8 1.6 1.6Mean duration 2.2 2.0 2.2 2.3

Heat Events, 1980-2006

Relative Risk (non-traumatic), Seattle

0.75

1.00

1.25

1.50

1.75

2.00

0 1 2 3 4 5

Heat event duration (days)

Rel

ativ

e R

isk

Aged 45+

Aged 65+

Aged 85+

Relative Risk (non-traumatic), East

0.75

1.00

1.25

1.50

1.75

2.00

0 1 2 3 4 5

Heat event duration (days)

Rel

ativ

e R

isk

Aged 45+

Aged 65+

Aged 85+

Projected Climate Parameters

0

2

4

6

8

10

12

1980

2000

2020

2040

2060

2080

2100

Number of Heat Events

1980

2000

2020

2040

2060

2080

2100

Greater Seattle Eastside

High

Moderate

Low

Projected Climate Parameters

0

1

2

3

4

5

6

7

1980

2000

2020

2040

2060

2080

2100

Average Duration of Heat Events

1980

2000

2020

2040

2060

2080

2100

Greater Seattle EastsideHigh

Moderate

Low

Projected Excess Deaths, Seattle†

0

250

500

750

1000

2025 2045 2085 2025 2045 2085 2025 2045 2085

Low Moderate High

85+

65-84

45-64

† Population held constant at 2025 projection

Projected Excess Deaths, East†

0

25

50

75

100

2025 2045 2085 2025 2045 2085 2025 2045 2085

Low Moderate High

85+

65-84

45-64

† Population held constant at 2025 projection

Discussion Why the difference between East and

West?


West? Our estimates of excess deaths due to

future heat are conservative Population growth not factored in Analysis of past heat events may

underestimate effect of longer, hotter events


West? Our estimates of excess deaths due to

heat are conservative Population growth not factored in Analysis of past heat events may

underestimate effect of longer, hotter events

Consider the possibility of higher-order failures

Limitations Use of county as geographic level linking

heat events and mortality

Reliability of climate and population projections

Change in cause-of-death coding during historical study period

Method does not allow for analysis of smaller, dispersed populations

Conclusions Heat Stress is already a significant

factor in Washington mortality

The number of heat-related deaths will increase because of climate change

AcknowledgementsCo-AuthorsMichael G. Yost PhD, UW Env & Occ Health SciencesCatherine Karr MD PhD, UW Env & Occ Health Sciences, PediatricsCole Fitzpatrick MA, UW Env & Occ Health SciencesBrian K. Lamb PhD, WSU Lab for Atmos Research, Civil & Env EngineeringSerena H. Chung PhD, WSU Lab for Atmos Research, Civil & Env EngineeringJack Chen PhD, National Research Council Canada, Ottawa, ON, CanadaJeremy Avise PhD, California Air Resources Board, Sacramento, CARoger A. Rosenblatt MD, UW Family MedicineRichard A. Fenske PhD, UW Env & Occ Health Sciences

CIG/JISAOPhil Mote PhDEric Salathe PhDAlan Hamlet PhDMarketa McGuire Elser PhDLara Whitely Binder

Heat-Related Mortality in Washington State: Past and Future The Washington Climate Change Impacts...

Documents

Transcript of Heat-Related Mortality in Washington State: Past and Future The Washington Climate Change Impacts...