## 5 IoT Systems in the Post-Disaster Stage  
### Sensors  
Excepted for environmental data [15; 90; 91; 92; 93], the sensors in the post-disaster stage mainly collect human health data [90; 92; 93; 94] and position data [15; 93; 94; 95; 93], which can improve the efficiency of search and rescue. Regarding environmental data, [PERSON] and [PERSON] [15] suggested using sensors to collect environmental data in terms of weather, chemicals, and movement. [PERSON] and [PERSON] [90] placed sensors on the buildings and in-pavements in the disaster-affected areas to collect environmental data, including water level, tilt in structures, temperature of buildings and ambient, smoke detection, obstacles in the path, visibility range, and location of the sensor. [PERSON] et al. [93] suggested using gas sensors to monitor air quality. Usually, multiple agencies participate in rescue operations. Each agency could use the sensors deployed in cities (e.g., weather stations, traffic cameras, wind sensors, precipitation meters, road surface condition sensors, and visibility meters) to collect environmental data [91; 92]. Also, the agency integrated its own sensors, such as unmanned vehicles equipped with GPS sensors, acoustic detection, distance measurement, and motion sensing, and drones equipped with GPS sensors and cameras [91; 92]. Regarding disaster mitigation, [PERSON] et al. [96] and [PERSON] et al. [47] collected water level data to open the floodgates. [PERSON] et al. [47] used ultrasonic sensors and a force-sensitive resistor to measure the water level. In addition, floods may cause pot holes on the road. [PERSON] et al. [80] developed pothole monitoring systems with a modem accelerometer and gyroscope. They used the Raspberry Pi as a single computer board. They placed the sensors on the vehicles. For building structure health detection after an earthquake, [PERSON] et al. [97] suggested using the LIS344 ALH accelerometer, TAOS 2561 light sensor, and SHT11 temperature and humidity sensors, which were installed on the Imote2 platform and ISM400 board. The human health data, including the rescuers' health data and the stranded people's health data, [PERSON] et al. [94] suggested that command posts should guarantee the safety of first responders through the body-worn sensors in wearable smart devices, such as smart glasses and smart watches. [PERSON] and [PERSON] [90] developed an IoT system to prioritize the evacuation of panicked, stranded people and provide them with timely medical support. They used the health sensors in stranded people's personal mobile communication devices to collect health data, including heart rate, breath rate, dizziness, sweating, chest pain, trembling, chills, choking, nausea, and the location of the individuals. In the rescue operations suggested by [PERSON] et al. [92], each rescuer was equipped with a personal sensor system (e.g., a tactical vest or tactical underwear) to monitor their health and position. The sensors in the tactical vest aimed to monitor water levels. The tactical underwater contained medical sensors, including one muscle activity sensor, pulse oximeters, and a heart rate sensor, which were installed on the Arduino single computer board. Regarding detecting epidemics in disasters, [PERSON] et al. [98] used the case of detecting COVID-19 in earthquakes to explain an IoT framework. In evacuation centers and temporary hospitals, they used thermal and infrared sensors to monitor people's body temperatures and detect fever. And they used heart rate sensors to measure oxygen levels and detect breathlessness. In affected areas, they monitored body temperature data through medical infrared thermometer guns. And they also deployed thermal sensors on unmanned aerial vehicles to monitor people's body temperature. [PERSON] et al. [93] used CO sensors, CO2 sensors, optical sensors (e.g., LWIR cameras, visual range cameras), vibration sensors, sound sensors, and an ion mobility spectrometer to detect and locate life.