dapple science meeting 30 th november 2004 department of environmental science & technology...

DAPPLE Science Meeting 30th November 2004

Department of Environmental Science & Technology Imperial College London, UK

EXPOSURE ASSESSMENT

S Kaur, M Nieuwenhuijsen, R Colvile


Aims & Objectives

• Characterise and evaluate human exposure levels at and around a street canyon intersection to CO and fine particulate matter

• Assess variations in exposure between and within i) modes of transport, ii) routes and iii) timings

• Examine the relationship between human exposure to PM2.5 and CO at and around a street canyon intersection in relation to fixed site monitored concentrations

• Identify and quantify the main determinants of human exposure at and around a street canyon intersection

• Consider the policy implications arising from the research

KEY:

Automatic Weather Station (AWS)

Route 1: Marylebone Road circuit Route 2: Gloucester Place & backstreet circuit

Ref. AWS

Start point/Endpoint

Start point/Endpoint


2003 Field Measurements


Results: Data Capture• 481 samples collected, 394 acceptable

samples

Overall Exposure to Pollutant N AM A SD Min. Max.

PM2.5 (µg/m3) 197 33.6 14.5 5.3 77.5

Ultrafine Particle Counts (pt/cm3) 86 88101 31291 36474 178601

CO (ppm) 111 1.0 0.7 0.0 2.9


Results: Timings

PM2.5

(µg/m) Ultrafine Particle Counts

(pt/cm3) CO(ppm)

Timing 1 2 3 1 2 3 1 2 3

(8.30am) (12.00pm) (3.15pm) (8.30am) (12.00pm) (3.15pm) (8.30am) (12.00pm) (3.15pm)

N 61 63 61 31 28 27 37 38 36

AM 34.6 28.8 35.6 106270 79188 76483 1.5 0.7 0.8

ASD 14.1 12.3 14.8 34075 25487 23818 0.7 0.5 0.5

Min. 12.5 6.0 5.3 52530 36679 36474 0.2 0.0 0.0

Max. 66.5 55.9 77.5 178601 128979 127326 2.9 2.0 1.8

913182125N =

Mode of Transport

TaxiCarBusCyclingWalking

Ave

rage

Ultr

afin

e P

artic

le C

ount

s (p

t/cm

3) 200000

180000

160000

140000

120000

100000

80000

60000

40000

20000

38

37

10

39

11


Results: Modes of Transport

1613272926N =

Mode of Transport

TaxiCarBusCyclingWalking

Aver

age

CO

exp

osur

e (p

pm)

3.0

2.5

2.0

1.5

1.0

.5

0.0

-.5

46


Results: Routes N AM A SD Min. Max.PM2.5 (µg/m3)

Marylebone Road Circuit 100 35.3 14.0 6.0 77.5Gloucester Place & Backstreets 97 31.8 14.7 5.3 71.8

Ultrafine Particle Count (pt/cm3)Marylebone Road Circuit 48 101142 29186 47300 178601Gloucester Place & Backstreets 38 71628 25844 36474 158685

Carbon Monoxide (ppm)Marylebone Road Circuit 61 1.3 0.6 0.4 2.9

Gloucester Place & Backstreets 50 0.6 0.5 0.0 2.0


Correlations between PollutantsCorrelation of Personal Exposure of PM2.5 and Carbon Monoxide

y = 0.0122x + 0.572R2 = 0.0545

0

0.5

1

1.5

2

2.5

3

3.5

0 10 20 30 40 50 60 70

PM2.5 (µg/m3)

CO

(ppm

)

Correlation of Personal Exposure to Carbon Monoxide and Ultrafine Particle Counts

y = 1E-05x - 0.2832R2 = 0.4594

0

0.5

1

1.5

2

2.5

3

3.5

0 20000 40000 60000 80000 100000 120000 140000 160000 180000 200000

Ultrafine Particle Counts (#/cm3)

Carb

on M

onox

ide

(ppm

)

Correlation of Personal Exposure to PM2.5 and Ultrafine Particle Counts

y = 1090x + 49544R2 = 0.2065

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

200000

0.00 10.00 20.00 30.00 40.00 50.00 60.00 70.00

PM2.5 (µg/m3)

Ultr

afin

e Pa

rticl

e C

ount

s (#

/cm

3 )


Ambient Monitoring

Comparison of Fixed Monitoring Site PM2.5 Concentrations and Average PM2.5 Exposure

9.9

22.6

33.6

0.05.0

10.015.020.025.030.035.040.0

London BloomsburyBackground Monitoring

Station

Marylebone Rd SupersiteKerbside Monitoring

Station

DAPPLE Exposure (2003)

PM2.

5 (u

g/m

3)

Comparison of Fixed Monitoring Site CO Concentrations and Average CO Exposure

0.3

1.5

1.0

0.00.20.40.60.81.01.21.41.6

London BloomsburyBackground Monitoring

Station

Marylebone Rd SupersiteKerbside Monitoring Station

DAPPLE Exposure (2003)CO (p

pm)


Results: Other


Data Analysed/Available (2003)


Aims & Objectives

• Characterise and evaluate human exposure levels at and around a street canyon intersection to CO and fine particulate matter✔

• Assess variations in exposure between and within i) modes of transport, ii) routes and iii) timings ✔

• Examine the relationship between human exposure to PM2.5 and CO at and around a street canyon intersection in relation to fixed site monitored concentrations ✔

• Identify and quantify the main determinants of human exposure at and around a street canyon intersection

• Consider the policy implications arising from the research


2004 Field Measurements


2004 Field Data Status


Analysis of Determinants of Exp.• Identify and quantify the

determinants of exposure• Regression: the model assumes

personal exposure is a function of independent variables (e.g. wind speed, wind direction, traffic density…etc) with a normally distributed random error

• Dependent on meteorological and traffic data availability

• Start with 2003 data

0

500

1000

1500

2000

2500

3000

00:0

0

03:0

0

06:0

0

09:0

0

12:0

0

15:0

0

18:0

0

21:0

0

00:0

0

Time of Day

Traf

fic/H

r.

T1 T2 T3

0

500

1000

1500

2000

2500

3000

00:0

0

03:0

0

06:0

0

09:0

0

12:0

0

15:0

0

18:0

0

21:0

0

00:0

0

Time of Day

Traf

fic/H

r.

T1 T2 T3


Timeline• Nov 2004 – Descriptive work for 2003 data complete• Dec 2004 – Start data collection for regression

analysis from other groups• Jan 2005 – Descriptive work for 2004 data complete• Mar/Apr ? 2005 – Basic analysis of determinants of

exposure for 2003 data complete• ????? Detailed analysis of determinants for 2003 data• ????? Analysis of determinants for 2004 data


Collaborators

• Health & Safety Laboratory, Sheffield (2003 & 2004) – exposure visualisation

• UCL – testing GPS and CO sensors• NERI – requested fieldwork completed,

awaiting funding

Bus exposure from Edgware Rd to Harley St: average of seating positions

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

200000

220000

1 16 31 46 61 76 91 106

121

136

151

166

181

196

211

226

241

256

271

286

301

316

331

346

361

376

391

406

421

436

451

466

481

496

511

bus journey time (seconds)

Ultr

afin

e pa

rtic

le c

ount

(avg

acr

oss

bus) AV-SD AV AV+SD

Bus starts from first stop

Bus exposure from Edgware Rd to Harley St: average of seating positions

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

200000

220000

1 16 31 46 61 76 91 106

121

136

151

166

181

196

211

226

241

256

271

286

301

316

331

346

361

376

391

406

421

436

451

466

481

496

511

bus journey time (seconds)

Ultr

afin

e pa

rtic

le c

ount

(avg

acr

oss

bus) AV-SD AV AV+SD

Bus starts from first stop

Exposure at a bus stop when buses stop there

0

20000

40000

60000

80000

100000

12000014

:27:

20

14:2

7:35

14:2

7:50

14:2

8:05

14:2

8:20

14:2

8:35

14:2

8:50

14:2

9:05

14:2

9:20

14:2

9:35

14:2

9:50

14:3

0:05

14:3

0:20

Time period

Parti

cula

te C

ount

Exposure at a bus stop when buses stop there

0

20000

40000

60000

80000

100000

12000014

:27:

20

14:2

7:35

14:2

7:50

14:2

8:05

14:2

8:20

14:2

8:35

14:2

8:50

14:2

9:05

14:2

9:20

14:2

9:35

14:2

9:50

14:3

0:05

14:3

0:20

Time period

Parti

cula

te C

ount


Bus Measurements

Top graph: example of timeseries ultrafine particle count at a bus stop (westbound, downstream of DAPPLE site on number 18 route) including peaks associated with arrival and departure of buses

Lower graph: average timeseries ultrafine particle count measured on multiple journeys between Edgware Road and Regents Park stations on number 18 route, including the section through the DAPPLE site.

Use of data to model exposure:1) Combine concentration at bus stop

with total waiting time and number of people waiting

2) Combine concentration on bus with journey time and bus occupancy

3) Note that most people experience the more polluted, delayed journeys! Clean buses have nobody on them!

dapple science meeting 30 th november 2004 department of environmental science & technology...

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