When affordable means hotter: The disproportionate heat risk of naturally occurring affordable housing in Los Angeles County

초록

This paper investigates the intersection of heat vulnerability and rental housing affordability by examining the association between the number of naturally occurring affordable housing (NOAH) units and extreme heat risk in Los Angeles County. Drawing on property-level rental data from CoStar, we estimate the prevalence of NOAH units affordable to households at 50% and 80% of Area Median Income (AMI), respectively. Integration with grid-level heat risk ratings from ClimateCheck assesses disparities in exposure to extreme heat between NOAH and higher-priced rental units. Employing multilevel mixed-effects negative binomial regression and spline models, our analyses demonstrate significant and complex associations between heat risk and the availability of NOAH units. First, the results indicate a consistent positive relationship: as heat risk increases, the prevalence of NOAH units rises. Second, further investigation reveals distinct nonlinear patterns by affordability level. Specifically, units for very low-income households (50% AMI) are acutely concentrated in the highest heat risk zones, whereas units for low-income households (50-80% AMI) are clustered in moderate-to-high risk areas. Third, disaggregated results by unit size reveal compounded risks for larger units; two-bedroom or larger NOAH units are especially likely to be located in hotter environments. This study contributes to climate justice research by documenting property-level spatial disparities across affordable housing stocks with varying affordability levels and unit sizes. Policy implications point to the integration of climate resilience into affordable housing preservation, prioritizing targeted adaptation strategies for the most affordable and larger NOAH units that face disproportionate heat risks.