Ozone Trends in a Residential Area in Las Vegas, 2001

Arsineh Hecobian

Map of Monitoring Station

Source: http://www.mapquest.com

http://major.ci.las-vegas.nv.us/website/clvcamps/viewer.htm

Monitoring Station

Palo Verde Site

Palo Verde High School far western edge of valley- new construction, high O3, -suburban site

DAQM Monitoring Stations

• DAQM operates fifteen sites to monitor Ozone

• DAQM operates eight sites to monitor the Oxides of Nitrogen

Ozone Exceeding 8-h AQI StdDate Station O3 ppm

9 Aug 01 Joe Neal 0.085

10 Aug 01 Winterwood 0.085

Shadowlane 0.087

Lone Mt 0.090

Palo Verde 0.091

Paul Meyer 0.085

W. Johnson 0.092

Joe Neal 0.094

11 Aug 01 Lone Mt 0.088

Palo Verde 0.090

Source: DAQM, 2001 NAMS/SLAMS NETWORK REVIEW, 2001

10th Percentile Comparison of O3 and NOx (June-01 Hourly Averages)

0.01

0.015

0.02

0.025

0.03

0.035

0.04

0.045

0.05

0.055

0:00 3:00 6:00 9:00 12:00 15:00 18:00 21:00 0:00

Hour

O3

ppm

0.005

0.006

0.007

0.008

0.009

0.01

0.011

0.012

0.013

0.014

NO

x pp

m

Ozone 10thNox 10th

90th Percentile Comparison of O3 and NOx (June-01 Hourly Averages)

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0:00 3:00 6:00 9:00 12:00 15:00 18:00 21:00 0:00

Hour

O3

pp

m

0.04

0.045

0.05

0.055

0.06

0.065

0.07

0.075

0.08

NO

x p

pm

Nox 90th

Ozone 90th

Comparison of Average NOx and O3 June and August 2001

June

0.03

0.035

0.04

0.045

0.05

0.055

0.06

0.065

0:00 3:00 6:00 9:00 12:00 15:00 18:00 21:00 0:00

Hour

O3 p

pm

0.005

0.01

0.015

0.02

0.025

0.03

0.035

NO

x p

pm

Ozone 50th

Nox 50th

August

0.025

0.03

0.035

0.04

0.045

0.05

0.055

0.06

0.065

0.07

0:00 3:00 6:00 9:00 12:00 15:00 18:00 21:00 0:00

H o u r

0.005

0.01

0.015

0.02

0.025

0.03

0.035

0.04

O3 Average

Nox Average

Comparison of Average Temperature and O3 June and August 2001

June

70

75

80

85

90

95

100

0:00 3:00 6:00 9:00 12:00 15:00 18:00 21:00 0:00

Hour

O3 p

pm

0.03

0.035

0.04

0.045

0.05

0.055

0.06

0.065

Tem

p

oF

Temp Average

Ozone Average

August

0.025

0.03

0.035

0.04

0.045

0.05

0.055

0.06

0.065

0.07

0:00 3:00 6:00 9:00 12:00 15:00 18:00 21:00 0:00

Hour

O3 p

pm

75

80

85

90

95

100

Tem

p

oF

O3 Average

Temp Average

Wind Direction Trends

• During the day: upslope, westerly

• At night: direction is reversed

50

100

150

200

250

300

350

400

0:00 3:00 6:00 9:00 12:00 15:00 18:00 21:00 0:00

Hour

Win

d D

irect

ion

0.01

0.02

0.03

0.04

0.05

0.06

0.07

Wind Dir

Ozone ppm

Mostly WNW

Mostly ENE

Mostly West

Wind Direction and Ozone

                                                                    

Source: http://www.summerlin.com/home.html

Summerlin Residential Area

Ozone and NOx

• Ozone loss by NOx catalyzed mechanism, not important in troposphere

• Loss of NOx by conversion to HNO3

• HOx & NOx catalyze O3 production in troposphere

• NO2 + h O2 NO + O3

Source: http://www.epa.gov/oar/oaqps/gooduphigh/#goodbad

Sources of NOx

Tropospheric Loss of O3

O(1D) + H2O 2OH

OH + O3 HO2 + O2

HO2 + O3 OH + 2O2

A Box Model

Summerlin Las Vegas

ELES

LD + LCS LD + LCL

FSL

FLS

Note: FLS >>>FSL winds are mostly to the west

An Estimation in August

• NOx production in LV = 823 tons/day

• Average wind speed = 5.5 MPH

• Summerlin = 15 miles

• Ignoring all other losses and sources:

• About 700 tons/day makes it to this station

Conclusions

• Correlation of Ozone with NOx

• Correlation of Ozone with Temperature

• NOx transportation from LV to PV