Human activities can cause concentrated emissions of greenhouse gases and other pollutants from cities. There is ongoing effort to convert new satellite observations of pollutants into fluxes for many cities. Here we present a method for determining the flux of three species (CO₂, CH₄, and CO) from the greater LA area using satellite (CO₂ only) and ground-based (all three species) observations. We run tests to estimate uncertainty and find the direct net CO₂ flux is 104 ± 26 Tg CO₂ yr⁻¹.