- A. Purpose of the Establishment of the Network
The establishment of the Air Quality Observation and Forecast Network was completed after comprehensive organizing and planing. The Network collects information and data regarding emissions, wind field, and air quality. The urban airshed model (UAM) analyzes air quality based on collected information, and divides Taiwan into 200 blocks. Based on the population, density, economic activities and geographic features, each block requires different numbers of observation stations. The most appropriate locations for the stations will be chosen based on financial, budgetary and maintenance concerns, priorities, and access to the land. The main purpose of launching the national system is to observe air quality and changes of air quality in larger regions.
- B. Observation items
Each air quality observation station may have collected different information, but generally, the observation includes the concentration of such pollutants as PM10, PM2.5, CO, SO2, NO, NO2 , NOx , O3, hydrocarbons, and acid rain, as well as meteorological parameters including wind direction, wind velocity, atmospheric pressure, UV radiation, temperature, relative humidity, and rainfall.
- C. Types of observation stations
At the end of 2006, the MOENV set up 76 air quality observation stations nationwide for the Air Quality Observation and Forecast Network. According to different observation purposes, the stations can be categorized into 4 industrial stations, 6 traffic stations, 4 background stations, 2 national park stations, and 63 general stations. Wanli, Sanyi and Hengchun stations can be categorized as general stations.
- D. Principles of observation instruments
This section introduces the instruments used by the Air Quality Observation and Forecast Network and how they read the concentration of major pollutants and meteorological parameters:
- Sulfur dioxide: Ultraviolet Fluorescence
- Carbon Monoxide: Nondispersive Infrared
- Ozone: Ultraviolet Absorption
- Nitrogen Oxides: Chemiluminescence
- Hydrogen Carbon: Flame Ionization Detector
- Particulate Matter: β-ray Attenuation method, Tapered Element Oscillating Microbalance Technology. The particulate analysis instrument automatically measures the concentration of PM10 and PM2.5 with a screening device and a mass calculation system. The former extracts airstream and different samplings to screen particulates by their diameters. The latter uses the attenuation of radiation and quassation to calculate the mass of particulates collected.
- Acid Rain: Electrode method
- BTEX: A gas chromatograph instrument equipped with PID and sample preparation to analyse the compound of BTEX (Benzene, Toluene, Ethylbenzene, and Xylenes) in air. The concentration may vary from 100 ppt to ppm.
- Wind field: wind direction and velocity
- Atmospheric pressure
- Adjustments and flow meters.