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With industrial escalation, the increase in air toxicity leads to air quality degradation. There is a necessity to monitor environmental pollutants to protect animals and human beings from toxic/hazardous gases. Some of the dangerous gases causing worry for humankind are NH₃, H₂S, CO₂, CH_4, and CO; inhaling them may lead to fatal diseases. H₂S is a colorless, poisonous, and flammable gas that causes immense toxicity among these gases. Several research groups work on gas sensors to monitor toxic and hazardous gases. Among various gas sensors, chemiresistive sensors are the best choice for detecting gases in the air environment. The metal oxide semiconductors like ZnO, CuO, NiO, SnO₂, etc., are suitable materials for synthesizing chemiresistive gas sensors as they have good conductivity with a wide range of operating temperatures. Apart from the choice of materials, the morphology of the nanostructures also influences the gas sensing performance. The nanofibers with a high surface area can capture more gas species, resulting in good gas sensing performance. Hence, the present review focuses on detecting H₂S by nanofibers-based chemiresistive gas sensors. The H₂S gas sensing characteristics were explored with various types of nanofibers. H₂S gas is hazardous, and its sensing applications can be found in petroleum and crude oil refineries. The surroundings of sewages pipelines, underground drainages, and sewage water treatment plants have a high level of H₂S gas contents. Therefore, it is necessary to monitor the H₂S gas levels in these areas for the safety of the workers and surrounding residents. The review article consists of various sensors that could be integrated with an IoT-based gas leakage detection system that can lower the risk of accidents in the manufacturing industry, agricultural activities, and emissions from automobiles, septic, and sewage treatment.

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