Transcript No Slide Title

Mapping Community Determinants
of Heat Vulnerability for the State of California
Courtney Smith
Prepared for the California Department of Public Health
Introduction
Table 2: Vulnerability Scores
Variable
Category
Vulnerability Score
Climate change is the greatest environmental health
threats of the 21st century. Many of its impacts, including
increased heatwaves, are already being felt.
Because not all populations are at equal health risk from
heat, knowing where vulnerable populations are located
can inform critical adaptation efforts. While understanding
vulnerability to heat at the individual level is important,
many additional factors, such as ethnicity, poverty,
diabetes rates, and air conditioning prevalence are all risk
factors highly associated with death from heat-related
events. These community determinants of heat
vulnerability were mapped to better understand the
geographical location of at-risk populations in California.
Percent below 1999 national poverty line
0-10%
0
10.1-20%
1
20.1-42%
2
0-30%
0
31-60%
1
61-100%
2
Percent people of color
Percent of households with no central air conditioning 13-15%
Percent of population with diabetes
0
15.1-21%
1
21.1-27%
2
27.1-55%
3
55.1-79%
4
3.5-6.3%
0
6.31-7.8%
1
7.81-9.7%
2
Results
Heat and Elevation
The map shows, that based on these four communitylevel variables, the Central Valley, North Central
California and Los Angeles are particularly vulnerable to
heat. From the contribution of each score to the final
vulnerability index, it appears high levels of poverty and
diabetes is driving much of the vulnerability in High
diabetes and poverty levels accounts for vulnerability
seen in the more rural areas.
There is also an association between heat and land
elevation due to adiabatic effects, with lower level
elevations experiencing great heat. While temperature is
the product of a complex system, visualizing elevation
differences in the LA basin may provide insight into
differential heat exposure. To do this, a DEM for the
region was retrieved from the USGS Seamless Data,
contours and a subsequent TIN created, then mapped
using ArcScene.
Community Determinants of Vulnerability to Heat
in Los Angeles County
Elevation Model of Los Angeles Basin
Methods
Variable Selection
Community-level variables associated with heat vulnerability
were identified. Statewide data for a subsection of these were
selected based on availability (summarized in Table 1). The
data was aligned so increasing values correlated with higher
vulnerability.
Geographic Coordinate System: GCS_North_American_1983
Datum: D_North_American_1983
Data Scaling
For data not available on the census tract level, the value for
larger regions were assigned to census tracts located in that
region. For instance, ac prevalence was only available by
Climate Zone(CZ) . CZ to zip code conversions were found,
allowing a conversion from zip codes to census tract by spatially
joining 2009 Tiger/LINE Shapefiles for both these geographic
levels.
Conclusion
Protecting the people are most vulnerable and least able
to prepare for the threat of heat waves will require a
targeted strengthening of public heath services and
infrastructure. Strategies that incorporate geographical
and social vulnerability can help in the allocation of
resources and the placement of infrastructure, such as
central cooling facilities.
Assigning Vulnerability Scores
Each variable was divided into categories based on distribution.
For each variable, each census tract was assigned a score
based on the categories’ influence on vulnerability (Table 2).
In the absence of detailed understanding of the impacts of each
variable on vulnerability, it was assumed each had equal impact
and summed assigned scores (using the Union tool), creating a
relative heat-vulnerability index for California.
Table 1: Heat Vulnerability Data
Variable
Data Source
Original Scale
Percent below 1999
national poverty line
U.S. Census 2000, Summary
File 3, www.factfinder.gov
Census tract (2000)
Percent people of color
U.S. Census 2000, Summary
File 1, www.factfinder.gov
Census tract (2000)
Percent of households with California Energy Commission, California Energy
no central air conditioning http://www.energy.ca.gov/applia Commission Climate
nces/rass/
Zones
Percent of population with
diabetes
California Department of Public County
Health, Diabetes in California
Counties, 2009
Geographic Coordinate System: GCS_North_American_1983
Datum: D_North_American_1983
Air conditioning rates, poverty and demographic characteristics are all driving
vulnerability in the LA area.
Objective
Limitations
To ensure the State’s public health infrastructure has the
capacity to withstand the challenges to health posed by
climate change and heat, it is essential to know which
communities or populations are most vulnerable and then
identify strategies and resources to diminish their risk.
Mapping community determinants of heat vulnerability
can inform local resource allocation and regional/
statewide emergency response planning efforts.
Scaling county and larger regional data down to the
census tract level for too many variables can hide many
disparities between census tracts located in the same
county/region. In addition, many other important
community-level variables, such as amount of impervious
service and green space are also strong determines of
community vulnerability; however, are not included here.
The State should particularly focus on the LA region as its
dense population and high risk means it offers the
greatest opportunity for avoided heat-related morbidity.
In addition to large at-risk populations, much of the LA
region is a flat basin that can suffer higher temperatures
with bordering mountains trapping heat.
Notes
All projections are in GCS North American 1983. Data
sources include U.S. Census 2000, the California Energy
Commission, the U.S.G.S Seamless Server, and the
California Public Health Department.
December 2010