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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
        Air Quality Objectives
Air Quality Objectives (AQO) for seven widespread
air pollutants were established in 1987
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
   11 General Air Quality Monitoring Stations
Station           Type of development area the station represents        Year start
                                                                         operation
Central/Western   Urban: residential                                       1983
Sham Shui Po      Urban: densely populated residential with commercial     1984
                  development
Eastern           Urban: densely populated residential                     1999
Kwun              Urban: densely populated residential with mixed          1983
                  commercial/ industrial developments
Kwai Chung        Urban: densely populated residential with mixed          1988
                  commercial/ industrial developments
Tsuen Wan         Urban: densely populated residential with mixed          1988
                  commercial/ industrial developments
Tai Po            Building New town: residential                           1990
Sha Tin           New town: residential                                    1991
Tung Chung        New town: residential                                    1999
Yuen Long         New town: residential with fairly rapid development      1995
Tap Mun           Rural                                                    1998
3 Roadside Air Quality Monitoring Stations

Station        Type of roadside conditions   Year start
               the station represents        operation

Mong Kok       Urban roadside with very        1991
               heavy traffic

Central        Urban roadside with very        1998
               heavy traffic

Causeway Bay   Urban roadside with very        1998
               heavy traffic
 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
Location of Air Quality Monitoring Station
                                                                        Tap
                                                                        Mun
              Yuen Long
                                Tai Po




                                 Tsuen Wan            Sha Tin

                                      Kwai Chung

                                          Shum Shui Po
                                            Mong Kok      Kwun Tong
                                                                      Roadside
                                      Central                         Station
 Tung Chung                                              Eastern
                    Central/Western                                   General
                                                Causeway Bay
                                                                      Station
     Population Covered by EPD’s AQM Network

EPD’s AQMS                                       Population 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 Station                                   Increasing
Tap Mun Station                                          Trace

     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
Causeway Bay Roadside Station
Causeway Bay Roadside Station
Mong Kok Roadside Station
Central Roadside Station
Tsuen Wan General Station
Tsuen Wan General Station
Tap Mun Background Station
              Stations Cost

                Capital      Annual operation/
                               development
 General      US$385,000       US$220,000
 Roadside     US$510,000       US$220,000

• 5 General stations are operated by private
  contractors at US$140,000 each
Parameters Monitored in the Network
         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
Quality Assurance Laboratory
Quality Assurance Laboratory (Calibration equipment)
       Maintenance Laboratory (Maintenance Schedule)

Equipment Type                         Time Intervals
                                          (Month)
Analyser            SO2 , CO , Ozone        18
                    NOx for Ambient         12
                    NOx for Roadside         6
Calibrator          Multi-gas               12
                    Ozone                   18
Zero Air Unit                               18
Manifold Controller Ambient                 12
                    Roadside                 6
Maintenance Laboratory (Calibration Room)
      Maintenance Laboratory




(Oscillating Microbalance)     (SO2 Analyzer)
Maintenance Laboratory
Computer Laboratory (Data Capturing Room)
Computer Laboratory (Server Room)
Computer Laboratory (Data Processing Room)
  Air Quality Annual Report

Air Quality Annual
Report can be
downloaded at:
http://www.epd.gov.h
k/epd/english/environ
mentinhk/air/air_qualit
y/aq_annualrpt.html
Monitoring Results
Monitoring Results
Long Term Trend
Long Term Trend
      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 Number
 API             Air Pollution Level
Number
  25     Half the Annual AQO, or a quarter of
         the one-hour or 24-hour AQO
  50     The Annual AQO, or half the one-
         hour or 24-hour AQO value
 100     The one-hour or 24-hour AQO
 200     Two times the one-hour or 24-hour
         AQO
                            API Bands
Descriptor      API                       Health Implications
  Low         0 to 25    Not expected.
 Medium
 Medium       26 to 50   Not expected for the general population.
  High       51 to 100   Few or none in the general population may notice
                         immediate health effects. Long-term effects may,
  High
                         however, be observed if you are exposed to such levels
                         persistently for a long time.
Very High 101 to 200 People with existing heart or respiratory illnesses may
                     notice mild aggravation of their health conditions.
Very High
                     Generally healthy individuals may also notice some
                     discomfort.
  Severe     201 to 500 People with existing heart or respiratory illnesses may
                        experience significant aggravation of their symptoms
 Severe                 and there will be also widespread symptoms in the
                        healthy population. These include eye irritation,
                        wheezing, coughing, phlegm and sore throat.
  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/forec
ast/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
Visibility Impairment
  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

				
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