1. 11 th Annual CMAS Conference October 15-17, 2012 1 Mohammed A Majeed 1, Golam Sarwar 2, Michael McDowell 1, Betsy Frey 1, Ali Mirzakhalili 1 1 Delaware Dept. of Natural Resources & Environmental Control, Division of Air Quality 2 U.S. Environmental Protection Agency, Office of Research & Development

2. Outline Trends in UFP number concentrations  At MLK and Lewes in Delaware  Descriptive statistics  Temporal and spatial variability Diurnal variations Weekday vs. weekend Seasonal Preliminary analysis of nucleation events Summary & Future work 2

3. Ultrafine Particles UFPs are particles  Diameter < 100 nm  Occur in large number, but hardly any mass Most common source  Dominated by vehicle exhaust in urban areas Adverse health effects may be closely related to UFPs Long range transport  Affect particle number & mass concentrations in urban areas  Accumulation particles can transport long distances Nucleation particles  Survive only a few hours due to coagulation and growth  Spatial scale of a max of few hundred kilometers Meteorological conditions and seasonal changes  Can influence particle number concentrations 3

4. Idealized Schematic for Atmospheric Particle Number Size Distribution 4 (Hussein, 2005)

5. European Union UFP Standards In 2005 the EU adopted “Clean Air for Europe” program For light duty vehicles with diesel engines  6 x 10 11 particles/km  Phased in - 2010 to 2012 5

6. 6 MLK Lewes

7. UFP Monitor (TSI Model 3031-1) & Sampling 7 TSI 3031-1 Ultrafine Particle Monitor and sampling system Photo: Ted Allen

8. 8 Monitoring Period  MLK: 11/2009 - 07/2011  Lewes: 01/2012 - 06/2012 Measurements made in six channels at 15-min intervals  Channel 1 :20-30 nm  N 30  Channel 2 :30-50 nm  N 50  Channel 3 :50-70 nm  N 70  Channel 4 :70-100 nm  N 100  Channel 5 :100-200 nm  N 200  Channel 6 :200-500 nm  N 500 UFP Measurements at MLK & Lewes

9. Descriptive Statistics for Similar Periods 9 MLK 2011 25 th PercentileMedian 75 th PercentileMaxMeanSD Jan26,70036,50054,300127,90041,90021,000 Feb20.50032,40049,400174,30038,00024,900 Mar12,20019,40029,700187,30023,00015,400 Apr12,90019,30028,20079,60022,40013,800 May15,20023,00028,30075,60025,40013,100 Jun20,50027,30035,60085,90029,80013,100 Lewes 2012 25 th PercentileMedian 75 th PercentileMaxMeanSD Jan5,9009,90015,70047,10011,2006,900 Feb8,30012,10016,70032,10012,9006,200 Mar6,5009,60015,10054,50011,8007,300 Apr12,900 19,50064,50015,0009,000 May5,8009,10019,50058,30011,8009,000 Jun9,20015,90025,80060,00017,90011,100 Total Number Concentration, cm -3.h -1

10. Particle Number Comparisons 10

11. Diurnal Pattern of Particle Number Concentration 11 Hour of Day

12. 12 Hour of Day June 2012 Seasonal Pattern of Particle Number Concentration for Weekdays Hour of Day June 2012

13. 13 Hour of Day Seasonal Pattern of Particle Number Concentration for Weekends June 2012

14. 14

15. Event Types 15 Noon Event: 2/07/2010 Three Peaks: 1/18/2010 Morning & Afternoon peaks: 1/27/2010

16. Classification of Events Short - lived Weak – dN 30 /dt: 5,000 cm -3 h -1 Moderate – 5,000 < dN 30 /dt < 10,000 cm -3 h -1 Strong - dN 30 /dt > 10,000 cm -3 h -1 16 Event Days at MLK YearMonthModerateStrong 2011Jan1310 Feb108 Mar115 Apr93 May73 Jun64 Jul22 Event Days at Lewes YearMonthModerateStrong 2012Jan10 Feb10 Mar11 Apr22 May11 Jun11

17. MLK: Evolution of Number Conc. on Strong Nucleation Days 17

18. 18 Lewes: Evolution of Number Conc. on Strong Nucleation Days 26 th May 2012 (Saturday)

19. MLK and Lewes data exhibit urban and rural differences in UFP counts MLK number concentrations are impacted by motor vehicle emissions  Morning and afternoon peaks are evident  Weekday and weekend differences are also evident UFP counts at urban site outnumber those at rural site Summer UFP counts at Lewes are most likely impacted by motor vehicle emissions Future Work  Further analysis on classification of events  Meteorological influences on nucleation  Apply the CMAQ model to simulate number concentration 19 Summary & Future Work