Visualizations

Tables

Description

This interactive dashboard provides both a visual and tabular look into heat vulnerability within Los Angeles. On the main page are three visualizations, with the main figure displaying the geospatial spread of urban-rural heat differences and median household income while the two side figures depict bivariate and univariate distributions of heat-related risk indicators respectively. The second page includes summary statistics and a full table of important heat vulnerability indicators where each observation represents a census tract in Los Angeles county.

Choropleth Map

The choropleth map created using the leaflet package in R offers an interactive toggling functionality that allows users to compare income and urban heat island index values across census tracts. The Urban Heat Island (UHI) Index variable comes from UCLA’s Healthy Places Index API, and is defined as a positive temperature differential reported in degree-hours per day on a Celsius scale between a given urban census tract and nearby upwind rural reference points at two meters above ground level, sourced from CalEPA in 2015. Larger values would indicate greater increases in temperature due to the urban heat island itself, separate from total heat. Census tract values for median household incomes are derived from the 2020 American Community Survey using a Census API and the tidycensus package in R. Toggling between the two layers shows how income distributions correlates with UHI index scores on a spatial level. As a general pattern, UHI is the lowest for tracts along the coast, which simultaneously represent some of the most affluent communities in Los Angeles. UHI is higher for inland and densely populated areas (as compared to suburbs north of LA), where income levels are more mixed, with both high and low income communities being impacted by intense UHI effects. Thus, considering geospatial distribution and variation is key as the choropleth map indicates that not all variation in UHI can be explained by socioeconomic or community-related attributes alone. In the context of urban planning, high-risk areas displaying both socioeconomic disadvantage and intense heat effects represent important targets for cooling infrastructure and green spaces development. At the same time, even regular citizens of Los Angeles are able to explore and analyze real-world connections between economic well-being and environmental challenges in urban areas through this web-based, interactive map tool.

Bubble Plot

The second bubble plot expands upon the findings of the map by showing how economic disadvantage can impact disparate heat-related outcomes through access to resources and cooling infrastructure. The x-axis represents the same median household income variable from Census data used in the choropleth map, while the y-axis variable represents census tract estimates of residential air conditioning (AC) probability empirically derived by Romitti et al. (2022) and ranked by percentile within Los Angeles’ core-based statistical area. The size and color of each bubble indicate the prevalence of stroke in a given census tract, derived from 2018 CDC PLACES data and imported from UCLA’s Healthy Places Index API. There appears to be a clear (but not necessarily linear) correlation between income, the availability of residential AC, and decreased prevalence of stroke.

Each variable in this multivariate plot suggests three core insights regarding the phenomenon of heat vulnerability within Los Angeles that are promising areas of study for further quantitative urban data analyses. Relative variation in heat vulnerability is inherently linked to a community’s larger socioeconomic context while also being impacted by specific infrastructure characteristics such as the availability of cooling units. Ultimately, urban disparities in heat effect have serious implications in public health outcomes like stroke and other acute heat-related illnesses (HRI), a pattern which is exacerbated for the elderly and individuals already diagnosed with chronic illness.

Lollipop Plot

The last visualization is a lollipop plot (a modified version of a classic bar plot) showing mean ozone concentration across heat event frequency quartiles. Mean daily maximum 8-hour ozone concentration (ppm) levels for each tract was measured in the summer months (May-October) between 2016-2018 and is derived from UCLA’s Healthy Places Index API. These values are then aggregated by quartiles of annual heat event frequency, as recorded in the National Risk Index (NRI) dataset. Ozone concentration can contribute to adverse public health outcomes in lung inflammation and other chronic respiratory issues on its own, but more importantly, is known to intensify urban heat island effects and heat vulnerability when co-occurring with already high land surface temperatures. This chart shows that communities in the third and fourth quartiles of annual heat event frequency also experience higher average measurements of ozone concentration compared to tracts below the median for annual heat events. It is clear that the impact of heat on a community is a product of so much more than just temperature, as urban, densely populated areas often experience disproportionate burden due to heat events given simultaneously high ozone pollution and other obstacles like limited cooling infrastructure and community resources.

Tabular View

Users can browse through key indicators like median income levels, UHI index, stroke prevalence, and AC availability in the dynamic table on the second tab while also viewing important summary statistics like the amount of census tracts included in the final dataset for analysis, number of LA census tracts coded as being socially vulnerable, and the mean prevalence of residential AC units on the top of this second page.

Ultimately, this dashboard is an easily accessible while still comprehensive tool for both policymakers and the general public to understand heat-related risks in Los Angeles and work together to address current disparities and develop equitable climate adaptation strategies.