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Pollutant Concentrations

Readings on 21 May 2015

View reading for:

Region 24-hr Sulphur dioxide
(µg/m3)
24-hr PM10
(µg/m3)
1-hr Nitrogen dioxide
(µg/m3)a
8-hr Ozone
(µg/m3)
8-hr Carbon monoxide
(mg/m3)
24-hr PM2.5
(µg/m3)
North 6(4) 25(25) 43(-) 4(2) 0.5(5) 12(51)
South 17(10) 22(22) 14(-) 5(2) 0.5(5) 12(48)
East 13(8) 17(17) 27(-) 10(4) 0.5(5) 11(46)
West 22(14) 28(28) 44(-) 14(6) 0.5(5) 15(54)
Central 9(6) 19(19) 29(-) 5(2) 0.7(7) 10(40)

1-hr PM2.5 (µg/m3)b Readings on 20 May 2015

View reading for:

Time 1am 2am 3am 4am 5am 6am 7am 8am 9am 10am 11am 12pm
North 14 16 11 12 8 10 8 14 11 21 19 13
South 10 5 5 6 16 7 5 6 5 6 15 21
East 11 10 12 10 10 13 10 14 8 8 12 13
West 12 16 12 7 12 16 7 11 21 14 13 26
Central 10 10 7 6 6 7 7 10 6 8 6 13
Time 1pm 2pm 3pm 4pm 5pm 6pm 7pm 8pm 9pm 10pm 11pm 12am
North 9 5 6 18 9 22 - - - - - 9
South 17 9 14 17 6 13 - - - - - 13
East 4 9 11 11 10 10 - - - - - 11
West 24 12 5 17 17 11 - - - - - 16
Central 11 9 14 11 7 10 - - - - - 11

Note:
a Sub-index for nitrogen dioxide is reported only when the 1-hr concentration equals or exceeds 1130 µg/m3.

b There is no sub-index for 1-hr PM2.5.

3-hr PSI Readings from 1am to 12am on 20 May 2015

Time 1am 2am 3am 4am 5am 6am 7am 8am 9am 10am 11am 12pm
3-hr PSI 42 46 44 40 39 41 40 40 39 45 48 53
Time 1pm 2pm 3pm 4pm 5pm 6pm 7pm 8pm 9pm 10pm 11pm 12am
3-hr PSI 54 52 44 47 48 52 - - - - - 52



The real-time data is automatically published as soon as it is generated by our air monitoring stations. The data is subject to verification and correction subsequently if necessary.