The metro system is the main mode of transportation in Taipei City. The air quality of metro stations is crucial for passengers. This study investigated particle size distribution and its elemental composition and assessed tunnel washing performance in the Taipei Rapid Transit System (TRTS). A 24-hour particle sampling process was performed in the tunnels, platforms, and entrances and exits to measure particulate matter (PM) 2.5 and PM 10 concentrations in an underground metro station and to analyze PM metal components. PM 10 and PM 2.5 concentrations decreased sequentially from the tunnels to the platforms and then to the entrances and exits to ambient environment in the metro station. The main metal components of suspended particulates in the TRTS mainly included iron, barium, copper, manganese, magnesium, aluminum, chromium, zinc, nickel, and lead. The total PM 10 and PM 2.5 metal proportions were 33.9%-24.7% and 32.9%-22.8%, respectively. Furthermore, the effectiveness of tunnel washing in reducing the PM concentration was investigated. Monitoring results showed an increase in PM 10 and PM 2.5 concentrations after tunnel washing on the first day. The PM concentration started to decrease from the second day. Furthermore, 3.5 months after tunnel washing, the PM 10 concentration decreased by 45.9%, and 2 months after tunnel washing, the PM 2.5 concentration decreased by 71.3%. The mechanism of the continuous reduction in the PM 10 concentration after cleaning is probably related to the porous material of tunnel walls, which may provide a deposition sink for aerosol particles, as well as the filter effect of the air conditioning system. This is the first study to use full-section tunnel washing to reduce PM exposure at mass rapid transit (MRT) stations. Although full-section tunnel washing reduced the PM concentration in the metro station, accessorial technology, such as the air conditioning system or platform design, may help in reducing the exposure of MRT passengers.

The production of greenhouse has become an important means to increase the income of China's rural areas and farmers, because the environment of greenhouses is controllable and the production is efficient. The temperature and humidity are the most important environmental impacts in the production of crop. The traditional regulation of the environment in greenhouses relies on artificial sampling detection which is inefficiency. Some advanced greenhouses use field wiring to implement the environmental regulation, but the environment is complex so field wiring is also a difficult problem. Aiming at solving the problem of monitoring the temperature and humidity in greenhouses, this paper designs a on-line monitoring system of greenhouses which is based on the wireless communication technology. The system adopts the DHT11 sensors to monitor the temperature and humidity in the greenhouse, and adopts the wireless communication technology of ZigBee so as to realize the online monitoring of the temperature and humidity. By using the wireless transmission and data acquisition nodes which are placed in different greenhouses can transmit the value of the temperature and humidity in greenhouses to the central node easily, and also realized the function of the online monitoring, alarm and transmitting data from different data acquisition nodes to the central node. The system consists of a data acquisition module, a wireless communication module, an alarm module and so on. The system is advanced because of its simple structure, small volume, low cost, easy operation, wide application range, strong scalability and so on. Compared with the traditional system, it can meet the demand of acquiring the temperature and humidity value of greenhouses in China.