Analyzing “Spikiness” in Diurnal Ozone Patterns in Houston

A Case Study Using Region 12 Data to Relate Industrial Emissions to Ambient Air Quality

Dave Sullivan OCE/MO and John Jolly OEPPA/TAD

Why is this important? Because figuring out what causes high O3 in Houston can save $100’s of

millions & protect public health.

In most other areas in Texas, ozone levels typically increase at a fairly predictable,

moderate rate

On high ozone days in Dallas, ozone rises at a steady rate of 15-25 ppb / hr

On high ozone days in Houston, ozone often rises suddenly 50 – 100+ ppb / hr. We believe this comes from the highly chemically reactive air in industrial areas

Given a complete set of monitoring data…

Upset reports, 5 minute resolution

ozone, wind speed, wind direction data,

Hourly auto-GC & other PAMS VOC data,

Area-wide data,

Then we may be better able to police air quality

5-Minute Ozone Readings for CAMS 35 (Deer Park)

9/20/99

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Ozon

e (pp

b)

Exceptionally steep rise inozone – about 140 ppb in30 minutes

1,3-butadiene upsetdiscovered at 8am

Using “Delta-max” to measure steepness of ozone increase/decrease for a monitor

for a day

1) Delta-max equals greatest hourly increase in ozone concentration

2) Delta-min is greatest hourly decrease following delta-max

3) High values for these two variables indicate possibility of upset emissions, and need to be investigated

4) Charts of delta-max vs delta-min plotted for 5-year period, 1995-99, for all area monitors

with >= 100 ppb hourly ozone

Delta-max and Delta-min at Deer Park CAMS 35 (industrial/urban monitor) 1995-

1999

High Delta-max values show spikiness of ozone concentrations in Houston Ship Channel area

Delta-max and Delta-min at Northwest Harris CAMS 26 (rural/suburban downwind monitor),

1995-1999

Note absence of high values – i.e. less spikiness

Comparing Delta Max in Houston and Dallas

Dallas emissions largely mobile and area sources – much less “spikiness”

Next two slides show distribution of delta-max values in Houston and Dallas over same 5-year period all area monitors >= 100 ppb hourly ozone included

note that Houston’s mean delta-max (34.9 ppb) is above 90th percentile in Dallas

Distribution of Delta-Max Values in Dallas – Ft Worth, 1995-99

Distribution of Delta-Max Values in Houston-Galveston, 1995-99

Case Study: 9/20/99

Severe early morning ozone spike at Deer Park C35 monitor

Ozone traveled downwind; spike subsequently recorded at 3 downwind monitors

1,3-butadiene spill reported in morning at a Dynegy plant located on north side of channel, some 6-8 miles NW of the Deer Park monitor

Amount reported was small (50 gals) but estimates of upset releases are notoriously inexact -- plus this is a highly reactive VOC

Map, forward trajectory, and diurnal ozone graphs follow

Map of Affected Area -- Ozone spike detected first at Deer Park, then subsequently at Texas City, Galveston, and Clute, respectively. Winds were from NW, shifting to NE later.

HYSPLIT 24-Hour Forward Trajectory for 9/20/99 Using Upper Air Data

13z (7am cst) start time

Red: 10m starting height

Blue: 100m starting height

Green: 500m starting height

filled icons (near shore): noon cst

outlined icons: 6pm cst

This trajectory starts near Ship Channel, shows initial NW wind flow, followed by NE shift

Local Wind DirectionUsing CAMS

(Deer Park met equipment not functioning; 2 adjacent monitors’ wind data shown)

9/20/99 Wind Direction at Monitors near Deer Park

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Houston East C1

Clinton

5-Minute Ozone Readings for CAMS 35 (Deer Park)

9/20/99

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ne

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)

Exceptionally steep rise inozone – about 140 ppb in30 minutes

1,3-butadiene upsetdiscovered at 8am

5-Minute Ozone Readings for CAMS 10 (Texas City)

9/20/99

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on

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Spike occurs about 1.5 - 2hours after Texas City

5-Minute Ozone Readings for CAMS 34 (Galveston)

9/20/99

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Spike registered herejust minutes after TexasCity

5-Minute Ozone Readings for CAMS 11 (Clute)

9/20/99

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Ozo

ne (

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4 hours later, spike registers fardownwind at Clute monitor

Name Description MWt MIR [d]2M-2-BUT 2-Methyl-2-Butene 70.14 14.45T3M2-C5E Trans 3-Methyl-2-Hexene 84.16 14.171M-CC5E 1-Methyl cyclopentene 82.15 13.95T-2-BUTE trans-2-Butene 56.11 13.9113-BUTDE 1,3-Butadiene 54.09 13.58C3M2-C5E Cis-3-Methyl-2-Hexene 84.16 13.3823M2-BUT 2,3-Dimethyl-2-Butene 84.16 13.32C-2-BUTE cis-2-Butene 56.11 13.222M-2-C5E 2-Methyl-2-Pentene 84.16 12.28PROPENE Propene 42.08 11.58ISOPRENE Isoprene 68.12 10.6923M2-C5E 2,3-Dimethyl-2-Hexene 98.19 10.411-BUTENE 1-Butene 56.11 10.29C-2-PENT cis-2-Pentene 70.14 10.24T-2-PENT trans-2-Pentene 70.14 10.232-C5-OLE 2-Pentenes 70.14 10.23ETHENE Ethene 28.05 9.08C6-OL2D C6 Cyclic or di-olefins 82.15 8.65C-2-C6E Cis-2-Hexene 84.16 8.44T-2-C6E Trans-2-Hexene 84.16 8.442-C6-OLE 2-Hexenes 84.16 8.44C-3-C6E Cis-3-Hexene 84.16 8.22T-3-C6E Trans-3-Hexene 84.16 8.16T4M2-C5E Trans 4-Methyl-2-Hexene 84.16 7.881M-CC6E 1-Methyl Cyclohexene 96.17 7.811-PENTEN 1-Pentene 70.14 7.79CYC-PNDE Cyclopentadiene 66.1 7.61C7-OL2D C7 Cyclic or di-olefins 96.18 7.49CYC-PNTE Cyclopentene 68.12 7.38T-2-C7E Trans-2-Heptene 98.19 7.333M-1-BUT 3-Methyl-1-Butene 70.14 6.99

Reactivity of 1,3-Butadiene compared to selected olefin species

(W. Carter, 5/2000, http://www.cert.ucr.edu/~carter/reactdat.htm)

Next: Looking at 1,3-butadiene at Deer Park

Deer Park Auto-GC measures 1,3-butadiene, but was not functioning on 9/20/99, hampering this investigation

Looked at data for this chemical at Deer Park in 1999 overall, instead

Following charts show wind directions, by frequency, of high 1,3-butadiene measurements

In 1999, very high measurements most frequently came from NNW -- same direction as 9/20/99

High 1,3-Butadiene Measurements by Wind Direction at Deer Park

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Number of measurements >= 20 ppb in 1999(n=15; 1999 mean = 1.006)

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Very

Summary O3 spikes in Houston from industrial emissions

From upset emissions or regular releases of reactive species

Results of summer 2000 & 2001 studies shed light on this

Auto-GC data at Deer Park on study date would have been useful in identifying 1,3 butadiene.

Without auto-GC data, FO spent time checking company records to find link between spill & ozone

Bottom line: MonOps & TAD need complete auto-GC and CAMS data to do forensic studies for Field Ops