A Survey of Wireless Sensor Network Based Air Pollution Monitoring Systems

Abstract

The air quality in urban areas is a major concern in modern cities due to significant impacts of air pollution on public health, global environment, and worldwide economy. Recent studies reveal the importance of micro-level pollution information, including human personal exposure and acute exposure to air pollutants. A real-time system with high spatio-temporal resolution is essential because of the limited data availability and non-scalability of conventional air pollution monitoring systems. Currently, researchers focus on the concept of The Next Generation Air Pollution Monitoring System (TNGAPMS) and have achieved significant breakthroughs by utilizing the advance sensing technologies, MicroElectroMechanical Systems (MEMS) and Wireless Sensor Network (WSN). However, there exist potential problems of these newly proposed systems, namely the lack of 3D data acquisition ability and the flexibility of the sensor network. In this paper, we classify the existing works into three categories as Static Sensor Network (SSN), Community Sensor Network (CSN) and Vehicle Sensor Network (VSN) based on the carriers of the sensors. Comprehensive reviews and comparisons among these three types of sensor networks were also performed. Last but not least, we discuss the limitations of the existing works and conclude the objectives that we want to achieve in future systems.

Keywords: Wireless Sensor Network (WSN); air pollution monitoring; high spatio-temporal resolution; low-cost ambient sensor; real-time monitoring.

Figure 1

Deployment of stationary monitors in Hong Kong [6].

Figure 2

Bead-type sensor.

Figure 3

Chip-type Sensor.

Figure 4

Basic Electrochemical Sensor.

Figure 5

Basic Light Scatting Particle Counter.

Figure 6

Basic Nephelometer.

Figure 7

Trade-off between tolerable sensor node cost, obtainable measurement coverage/resolution, expected data quality and achievable measurement temporal resolution for Conventional Stationary Monitoring Network (CSMN), Static Sensor Network (SSN), Community Sensor Network (CSN) and Vehicle Sensor Network (VSN) [100].

Figure 8

Example of the SSN system architecture and prototype. Red dots are the sensor nodes. Green dots are the gateways that forwarding the acquired data to the Contaminant Source. Figures are adapted from [101].

Figure 9

Example of the Community Sensor Network (CSN) system architecture and prototype. Figures are adapted from [109].

Figure 10

Example of the Vehicle Sensor Network (VSN) system architecture and prototype. Figures are adapted from [98].

Figure 11

Grading result of the six major comparison properties in Static Sensor Network (SSN), Community Sensor Network (CSN) and Vehicle Sensor Network (VSN) (‘0’ means ‘None’; ‘1’ means ‘Low/Short/Inconvenient’; ‘2’ means ‘Medium’ and ‘3’ means ‘High/Long/Convenient’).