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AIR QUALITY ANALYSISAIR QUALITY ANALYSIS

A Study on Changes in Specifications for Gasoline and Diesel Fuels in Thailand

Daedalus LLC/ERM Siam

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AIR QUALITY ANALYSISAIR QUALITY ANALYSIS

OZONE

Daedalus LLC/ERM Siam

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OverviewOverview

ObjectivesData Accuracy and CompletenessFrequency of ExceedancesVOC and NOx LimitationWeekday/Weekend ConcentrationsProjectionsConclusions

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ObjectivesObjectives

Evaluate data qualityDescribe frequency of exceedancesDetermine where and when ozone

formation is VOC or NOx limitedCompare weekdays and weekendsProject future ozone trends

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Data Accuracy/CompletenessData Accuracy/Completeness

O3, NOx, Co showed high data quality

Number of days with ozone data– 11 sites in 1997 had > 330 days– > 6 sites in 1998 had > 330 days

Incomplete ozone sampling may miss some exceedances

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0

20

40

60

80

100

120

140

160

12 13 14 15Date

09T 10T 12T 22T 23TSite

Ozone Data Showed Consistency Among Sites:An Example of Exceedances on January 13, 1997

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06T 09T 10T 11T 12T 13T 14T 20T 22T 23T 27T 52T 53T 54T0

50

100

150

200

250

300

350

400

Site1997 1998

Number of Days With Ozone Measurements

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Frequency of High Ozone ValuesFrequency of High Ozone Values

Site maxima of 85 to 190 ppbv77 days over 100 ppbv in 199742 days over 100 pbbv in 1998Maximum number of days over

100 ppbv at one site was 26 at site 20T in 1997

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06T 09T 10T 11T 12T 13T 14T 20T 22T 23T 27T 52T 53T 54T0

5

10

15

20

25

30

Sites

Frequency of Days With OzoneExceeding 100 ppb in 1997

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09T 10T 11T 12T 13T 14T 20T 22T 23T 27T 52T 53T 54T0

5

10

15

20

25

Sites

Frequency of Days With OzoneExceeding 100 ppb in 1998

Note: 20T had 98 sampling days

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Number of Days With Peak Ozone Over 100 ppbvJanuary -March and October -December 1997

B B

B

B

BB J

J

J

J

J

J

HH

1480

1500

1520

1540

1560

1580

600 620 640 660 680 700UTME (km)

B 0 to 5

J 6 to 15

H 16 to 25

Number Days Ozone > 100 ppb

Jan - Mar and Oct - Dec 1997

Dept. Med Sci. (22T)

Nakhonpratom (23T)

Salaya Mahidol (06T)EGAT Bang Karuy (13T)

Rangsit (20T)

Kongjan (10T)Chaochai (53T)

Ramkhamhaeng (09T)Thonburi Hwy Dist (14T)Electricity Thonburi (52T)

None-tree (12T)

Huai Khwang Sport Center (11T)

Din Daeng (54T)

Samut Sakhon (27T)

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Frequency of Days With OzoneExceeding 100 ppb by Month

1 2 3 4 5 6 7 8 9 10 11 120

2

4

6

8

10

12

14

16

18

Month1997 1998

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VOC and NOx LimitationVOC and NOx Limitation

Most hours and sites VOC- limited8 sites strongly VOC- limited 6 sites transitionalNo sites strongly NOx- limited

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09T 10T 11T 12T 13T 14T 20T 22T 23T 27T 52T 53T 54T0

5

10

15

20

25

30

35

40

45

SITE

VOC Limited Transitional NOx Limited

Number of Hours of VOC and NOx LimitationWhen Ozone >100 ppb in 1997-1998

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VOC or NOx Limitation of Peak Ozone FormationFive Highest Days Each Year at Each Site, 1997-98

B

BBJ J

J

J

J HH

H

H

H

F

1480

1500

1520

1540

1560

1580

600 620 640 660 680 700UTME (km)

B < 0.4

J 0.4 to 0.6

H 0.6 to 0.8

F > 0.8

Mean Extent of Reaction

High-Ozone Days, 1997-98

Dept. Med Sci. (22T)

Nakhonpratom (23T)

Salaya Mahidol (06T)EGAT Bang Karuy (13T)

Rangsit (20T)

Kongjan (10T)Chaochai (53T)

Ramkhamhaeng (09T)Thonburi Hwy Dist (14T)Electricity Thonburi (52T)

None-tree (12T)

Huai Khwang Sport Center (11T)

Din Daeng (54T)

Samut Sakhon (27T)

VOC limited

Transitional

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Sunday Versus WeekdaySunday Versus Weekday

Sunday NOx 23% lower than weekdaySunday NMHC 26% lower than weekdaySunday ozone 5 - 20 ppb lower than

weekday

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SUN MON TUE WED THU FRI SAT0

10

20

30

40

50

60

70

80

90

Day of Week

6-9 am 10am-1pm 2-5pm

Mean NOx Concentrations at Site 13TBy Day of Week in 1997 and 1998

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01T 02T 03T 13T 14T 16T 17T 19T 22T 23T 27T 52T 53T 54T0

5

10

15

20

25

30

35

40

45

Site

Hours 6 to 9 Hours 10 to 13

Percentage Decrease of Mean Sunday NOx ConcentrationsCompared With Mean Weekday Concentrations, 1997-98

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05T 13T 14T 23T 27T 52T 53T 54T0

5

10

15

20

25

30

35

40

45

Site

Hours 6 to 9 Hours 10 to 13

Percentage Decrease of Mean Sunday NMHC ConcentrationsCompared With Mean Weekday Concentrations, 1997-98

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Difference Between Mean Sunday Peak Ozone and Mean Weekday Peak Ozone

Five Highest Days for Each Day of the Week per Year, 1997-98

B

J

J

J

J

J

JJ H

HH

H

H

H

1480

1500

1520

1540

1560

1580

600 620 640 660 680 700UTME (km)

B 0 to 10 increase

J 0 to 10 decrease

H 10 to 20 decrease

Mean Sunday Peak Ozone - Mean Weekday Peak Ozone

High-Ozone Days, 1997-98

Dept. Med Sci. (22T)

Nakhonpratom (23T)

Salaya Mahidol (06T)EGAT Bang Karuy (13T)

Rangsit (20T)

Kongjan (10T)Chaochai (53T)

Ramkhamhaeng (09T)Thonburi Hwy Dist (14T)Electricity Thonburi (52T)

None-tree (12T)

Huai Khwang Sport Center (11T)

Din Daeng (54T)

Samut Sakhon (27T)

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Projections for 2005 and 2010Projections for 2005 and 2010

Emission Projections– 2005: 17% greater NOx; 7% lower HC– 2010: 30% greater NOx; 20% lower HC

Ozone is now usually VOC-limitedImplies future ozone 5- 10 ppbv

lower at existing monitoring sitesOzone may increase far downwind

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ConclusionsConclusions

Frequent ozone days over 100 pbbvVOC-limited most hours and sitesNOx, NMHC, O3 lowest on Sundays

Project lower ozone due to lower NMHC by 2010