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Roadside Air Quality Monitoring Compared with Ambient Air Quality Monitoring in Hong Kong BAQ 2004 Agra, India 6 – 8 December 2004 HA Kong, Albert LEUNG Environment , Transport and Works Bureau Hong Kong Special Administrative Region Government.
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Roadside Air Quality MonitoringCompared with Ambient Air Quality Monitoringin Hong KongBAQ 2004Agra, India6 – 8 December 2004HA Kong, Albert LEUNGEnvironment, Transport and Works BureauHong Kong Special Administrative Region Government
Air Quality Objectives (AQO) for seven widespread air pollutants were established in 1987 Air Quality Objectives
Objective of Monitoring Network • To assess how far Air Quality Objectives are achieved • To assess public’s exposure to air pollution • To understand air pollution problems and assist finding solutions • To provide input on validating control measures and formulate future AQMP • To provide public information and forecast air quality (Air Pollution Indexes)
Air Quality Monitoring Network in Hong Kong • Fixed monitoring stations • 11 general air quality stations • 10 ambient and 1 background • 3 roadside stations • 2 General Air Quality stations started 1983 • 1 Roadside station started 1991 • Up to 4 short term field stations
Air Pollution Sources in HK Both general air quality stations and roadside stations because of two distinct sources • Local Vehicles • Regional Commercial and Industrial Operations
Yuen Long Kwai Chung Shum Shui Po Kwun Tong Roadside Station Tung Chung Eastern General Station Location of Air Quality Monitoring Station Tap Mun Tai Po Sha Tin Tsuen Wan Mong Kok Central Central/Western Causeway Bay
Population Covered by EPD’s AQM Network EPD’s AQMSPopulation Covered Kwun Tong Station 658,000 Sha Tin Station 444,000 Tai Po Station 281,000 Yuen Long Station 273,000 Sham Shui Po Station 1,156,000 Central / Western Station 376,000 Tsuen Wan Station 247,000 Kwai Chung Station 471,000 Eastern Station 578,000 Tung Chung StationIncreasing Tap Mun StationTrace Total Population covered Hong Kong Total Population Representing Percentage by the Network 4,484,000 6,207,000 72 % Data Source: 1996 Population By-census Short term field stations to cover other areas and hot spots
Stations Cost • 5 General stations are operated by private contractors at US$140,000 each
Quality Control (QC) and Quality Assurance (QA) A high degree of accuracy and precision • Accuracy: to within 20% (gaseous pollutants) or 15% (particulates) of the certified reference value • Precision: to within 15% (gaseous pollutants & particulates) of the mean value • Data capture rate: 85% or above of the total possible numbers of data
Quality Control (QC) and Quality Assurance (QA) • Requirements are the same for all stations • Instruments are designated by USEPA • Calibration standards are traceable to international primary standards • Certified under Hong Kong Laboratory Accreditation Scheme (HOKLAS) • Independent annual audit under HOKLAS • Inter-laboratory comparison with overseas air monitoring term every four years
Maintenance Laboratory (Oscillating Microbalance) (SO2 Analyzer)
Air Quality Annual Report Air Quality Annual Report can be downloaded at: http://www.epd.gov.hk/epd/english/environmentinhk/air/air_quality/aq_annualrpt.html
Air Pollution Index (API) • Data are transmitted to data processing centre to calculated API • Index are calculated by comparing the measured concentrations of major air pollutants against air pollution levels with reference to AQO • Five major air pollutants - Nitrogen dioxide - Sulphur dioxide - Ozone - Carbon monoxide - Respirable suspended particulates (RSP)
API Bands Low Medium High Very High Severe
General API & Roadside API • The General API reflects the level of air pollution which the public exposed to most of the time. It comes from measurements at 11 general air quality monitoring stations • The Roadside API states the level of air pollution at the roadside with very heavy traffic and tall surrounding buildings
Current & Forecast API available on web Updated hourly at: http://www.epd-asg.gov.hk/eindex.php & http://www.epd-asg.gov.hk/english/forecast/forecast.php
Conclusion • Improving roadside data confirmed that vehicle emission control measures are taking effects • Deteriorating general data points to regional effects taking on a more significant role • Continue our current efforts on the monitoring network with more focus on field stations
Additional Information Environment, Transport and Works Bureau k_ha@etwb.gov.hk http://www.etwb.gov.hk Environmental Protection Department albertleung@epd.gov.hk http://www.epd.gov.hk Thank You