This paper reviews the mechanisms, parameters, and applications of metal oxide chemoresistive gas sensors. The economic growth of countries heavily relies on MSMEs, and transportation is a vital component. However, industries and vehicles emit harmful gases, which impact human health and air quality. Traditional air monitoring methods are expensive, leading to limited stations in many countries. Nanotechnology has developed soft metal oxide materials that can sense various gases at low concentrations and work in different environmental conditions. Ferrite-based sensors have been primarily used to detect harmful gases and pollutants from vehicle exhaust and environmental monitoring. The tuning of ferrite sensors depends on synthesis techniques, preparation conditions, sintering temperatures, operating temperatures, dopant concentrations, and other factors. The key parameters for ferrite gas sensors include phase formation, crystallite size, grain size, surface area, selectivity, dopants, sensitivity, gas concentration, operating temperature, and response/recovery time. The study focuses on the impact of high concentrations of gases such as hydrogen (H₂), carbon monoxide (CO), carbon dioxide (CO₂), oxygen (O₂), ethylene glycol (CH₂OH₂), methane (CH₄), ammonia (NH₃), liquid petroleum gas (LPG), acetylene (C₂H₂), and nitrogen oxides (NOx) on the environment and the selection of metal oxide materials for sensor applications. The paper also discusses the classification of sensors based on their operating principles, including electrochemical, optical, acoustic, catalytic, magnetic, photoionization, semiconductor, and infrared gas sensors. Metal oxide-based sensors are highlighted for their advantages over traditional sensors, such as high sensitivity, small size, durability, and low cost. The synthesis techniques for preparing nano-ferrites, including hydrothermal, co-precipitation, sol-gel, solid-state reaction, and combustion/citrate precursor methods, are described. The gas sensing mechanism in chemoresistive metal oxides and semiconductor gas sensors is explained, focusing on the adsorption and ionization of oxygen species and the change in resistance due to gas presence. The paper also covers the fabrication of gas sensors, including bulk-pellet, thick film, and thin film sensors, and the influence of factors such as temperature and humidity on sensor performance. The testing of sensor materials involves a valve, thermostat, gas chamber, electronic device, and vacuum pump. Finally, the paper provides a comparative study of different gases, including CO₂, LPG, NO₂, H₂, and NH₃, focusing on their composition, synthesis techniques, morphology, gas concentration, temperature, sensitivity, and response/recovery time. The need for new materials to improve sensor performance in detecting these gases is emphasized.This paper reviews the mechanisms, parameters, and applications of metal oxide chemoresistive gas sensors. The economic growth of countries heavily relies on MSMEs, and transportation is a vital component. However, industries and vehicles emit harmful gases, which impact human health and air quality. Traditional air monitoring methods are expensive, leading to limited stations in many countries. Nanotechnology has developed soft metal oxide materials that can sense various gases at low concentrations and work in different environmental conditions. Ferrite-based sensors have been primarily used to detect harmful gases and pollutants from vehicle exhaust and environmental monitoring. The tuning of ferrite sensors depends on synthesis techniques, preparation conditions, sintering temperatures, operating temperatures, dopant concentrations, and other factors. The key parameters for ferrite gas sensors include phase formation, crystallite size, grain size, surface area, selectivity, dopants, sensitivity, gas concentration, operating temperature, and response/recovery time. The study focuses on the impact of high concentrations of gases such as hydrogen (H₂), carbon monoxide (CO), carbon dioxide (CO₂), oxygen (O₂), ethylene glycol (CH₂OH₂), methane (CH₄), ammonia (NH₃), liquid petroleum gas (LPG), acetylene (C₂H₂), and nitrogen oxides (NOx) on the environment and the selection of metal oxide materials for sensor applications. The paper also discusses the classification of sensors based on their operating principles, including electrochemical, optical, acoustic, catalytic, magnetic, photoionization, semiconductor, and infrared gas sensors. Metal oxide-based sensors are highlighted for their advantages over traditional sensors, such as high sensitivity, small size, durability, and low cost. The synthesis techniques for preparing nano-ferrites, including hydrothermal, co-precipitation, sol-gel, solid-state reaction, and combustion/citrate precursor methods, are described. The gas sensing mechanism in chemoresistive metal oxides and semiconductor gas sensors is explained, focusing on the adsorption and ionization of oxygen species and the change in resistance due to gas presence. The paper also covers the fabrication of gas sensors, including bulk-pellet, thick film, and thin film sensors, and the influence of factors such as temperature and humidity on sensor performance. The testing of sensor materials involves a valve, thermostat, gas chamber, electronic device, and vacuum pump. Finally, the paper provides a comparative study of different gases, including CO₂, LPG, NO₂, H₂, and NH₃, focusing on their composition, synthesis techniques, morphology, gas concentration, temperature, sensitivity, and response/recovery time. The need for new materials to improve sensor performance in detecting these gases is emphasized.