AbstractRecent investigations reveal an increasing interest in detecting toxic substances that, if present in the environment at low concentrations, can cause serious health conditions. Moreover, some of these toxic substances can be found as gases in human breath due to disease. Nanomaterial-based sensors have emerged as a crucial area of research for this purpose. This study focuses on silver-doped tungsten oxide nanoparticles (Ag/WO₃) as nanosensors capable of detecting trace amounts of toxic gases at room temperature. These gases include Hydrogen sulfide (H₂S), as well as other toxic gases like acetone, Ammonia (NH₃), Ethanol (C₂H₅OH), and Acetone ((CH₃)₂CO). The gas-sensing behavior of Ag/WO₃ nanosensors was investigated at extremely low concentrations of these gases. X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) were employed to analyze the material's structure and chemical state. The sensor exhibited sensitivity to gas concentrations as low as 0.25 ppm, with a robust response of up to 80%. Notably, it showed the highest selectivity toward H2S gas compared to ethanol, ammonia, and acetone. The sensor's performance was also evaluated under varying temperatures and humid conditions, demonstrating reliable responses at room temperature. Heron, the synthesis of Ag/WO₃ sensors with excellent sensitivity at extremely low gas concentrations is reported, making this sensor a promising tool for detecting toxic gases that threaten human health. Furthermore, the potential implications of this research on human health are significant, as detecting low concentrations of these gases can be a potential tool for the diagnostic process as well as health and environmental monitoring.