<p>Human exposure to lead (Pb) is a global health concern, yet existing technologies for detecting lead in our environment remain prohibitively expensive for widespread deployment. Here we present a new theoretical concept towards lead screening using X-ray fluorescence (XRF) in an unconventional geometry we coin <i>transmission XRF</i> in which the sample is placed between the source and detector. For cost reduction, we then show that ²⁴¹Am found in ionizing smoke detectors is spectrally suitable for Pb L-shell XRF generation and can thus replace X-ray tubes used in conventional XRF devices. Exploring soil screening as the first application, we demonstrate with Monte Carlo simulations that a configuration with 7&#xa0;×&#xa0;²⁴¹Am sources and a standard silicon drift detector could enable screening-relevant detection limits (100 ppm Pb) in soil within practical measurement times (&lt;30 min). We believe this concept opens a route toward low-cost and scalable XRF instrumentation for democratizing lead screening across a wide range of samples.</p>