## 4 Applications of WSN in Urban Areas
### Gas Monitoring Applications  
Gas monitoring in urban areas is a critical application of WSNs aimed at ensuring safety and environmental quality. In urban regions, the proliferation of industrial activities, vehicular emissions, and residential gas usage poses significant challenges to air quality and public health. WSNs facilitate real-time monitoring of gas emissions, allowing for early detection of leaks, pollutants, and hazardous concentrations. However, challenges such as sensor calibration, data accuracy, and network reliability need to be addressed to ensure effective gas monitoring. Precautions such as regular sensor calibration, redundant sensor deployment, and network optimization can enhance the accuracy and reliability of gas monitoring systems. Additionally, proactive maintenance and timely response protocols are essential to address any detected anomalies or gas leaks promptly, mitigating potential risks to public health and safety. Overall, leveraging WSNs for gas monitoring in urban areas offers a scalable and efficient solution to address environmental concerns and ensure the well-being of urban inhabitants. [PERSON] et al. (2019) [41] proposed a real-time and early-warning gas leakage monitoring system for large-scale regions using mobile WSNs. The system utilized Zigbee-based antenna types along with Global Position System (GPS) sensors and employed a combination of centralized and hierarchical network topologies. The sensor terminal included Tunable Diode Laser Absorption Spectroscopy (TDLAS) gas sensors, known for their high accuracy and compact size, enhancing the efficiency of gas detection. A central server was responsible for gathering, processing, and storing information, while a real-time monitoring cloud platform displayed the data. The mobile WSN consisted of both mobile and stationary sensor terminals for comprehensive gas leakage monitoring. This work addressed the critical need for timely detection and warning of gas leaks in large-scale urban environ  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c c c c} \hline \hline
**Ref. No. ** & **Method Name** & **Objective** & **Sensor Type** & **Network Type** & **Topology** & **EC** & **N1** & **E** & **Daily** & **BO** & **T** & **LR** & **R** & **ET** & **Cost** & **CO** & **Limitations** \\ \hline \multirow{3}{*}{[3]} & Cross-sectional & Target all healthcare & & & & & & & & & & & & & & & Delay using cross-sectional approach & \\  & descriptive design & & & & & & & & & & & & & & & & & & \\  & & & & & & & & & & & & & & & & & & \\  & & & & & & & & & & & & & & & & & & & \\ \hline \multirow{3}{*}{[4]} & Initial bibliometric analysis & Analyse data for healthcare & EARC, ECC, ECCs & & & & & & & & & & & & & & & & \\  & & applications in cellular way & & & & & & & & & & &  
ments. By leveraging mobile WSNs and advanced sensor technology, the system aimed to mitigate potential hazards associated with gas leaks, ensuring the safety of residents and infrastructure. The results demonstrated the effectiveness of the proposed system in real-time gas monitoring and early warning, providing valuable insights for enhancing urban safety and environmental protection. [PERSON] et al. (2013) [42] discussed the gas detection method. The designed method focused on employing gas sensors for fiber detection, aiming to enhance the efficiency and accuracy of gas detection processes. The designed system utilized a decentralized network and cluster-based network topology, facilitating comprehensive coverage and data collection. The research addressed challenges associated with traditional gas detection methods, such as limited coverage and detection capabilities. By leveraging advanced sensor technologies and network architectures, the gas detection method is used in various applications, including industrial settings and environmental monitoring.