exposure assessment pag meeting, 14/07/2003 surrey university
TRANSCRIPT
DDispersion
EEmissions
MMovement
Buildings
Synoptic Meteorology
Vehicle-Induced
Turbulence
Road
Design
Determinants of exposure
- apply to determinants of temporal variability in exposure averaged over a population,
as well as variation of time-averaged exposure across population
Exposure Routes
Route 1 : Marylebone Road, heavily trafficked
Route 2 : back streets with crossings of Marylebone Road
Digital Data © Geoinformation Group (2002)
Equipment
CO T15 Langan - Measures carbon monoxide every 10 seconds
Casella Ultraflow Pump + Filter - average PM2.5 conc.
TSI P-Trak - Measures ultrafine particles every second
Walking & CyclingRoutes 1 & 2, 06/05/03 a.m. (40-minute journeys)
Peaks crossing Marylebone Rd, otherwise in general 25% less pollution in backstreets
People walking along Marylebone Rd experience peak particulate pollution approx 50% less than those cycling
DDispersion
EEmissions
MMovement
Buildings
Synoptic Meteorology
Vehicle-Induced
Turbulence
Road
Design
Measurements to understand determinants of exposure in more detail
• Speciated measurements (PM2.5 and VOCs)• Spatial variability over a common averaging time, including indoor/outdoor ratios• Time-series at a fixed point• Measurement of sensitivity to parameters that can be controlled•Visualisation of relationship between exposure and activity
Elemental carbon
• Each PM2.5 filter, in addition to weighing for total mass, has reflectance measured
• Paired samples for reflectance and laboratory analysis exposed at variety of representative fixed locations, with Quartz filters sent for laboratory analysis for elemental carbon
• Awaiting results from lab, but quality check has discovered correction factor to apply to mass on PTFE filters
• Elemental carbon shows more spatial variability than total mass
Indoor (WCC) / Outdoor
Variations in indoor and outdoor particulates and VOCs between:• WCC rooms on different levels; and • with different aspects2 MSc projects
Summary of preliminary VOC measurements (BRE)
• Outdoor spatial variability greater than limited measurement of temporal variability
• Different speciation indoors to outdoors, especially in one room obviously strongly dominated by indoor sources
• Is indoor temporal variability greater than street canyon temporal variability?
• What are the implications of this for using outdoor background measurements as a surrogate for exposure?
1st Deployment: 5-VOC Concentrations Indoor & Outdoor Locations
3.23.8
2.6 2.7 2.71.8
9.2
1.2 1.5
0.3 0.5
3.1
0.3 0.3 0.61.7 2.0
6.3
4.75.6
4.95.7
11.5
5.4
3.3
18.8
27.2
<0.1<0.1<0.1<0.1<0.1<0.1 <0.1
64.4
<1.4<1.4
<1.41.4
1.4
0
10
20
30
40
50
60
70
R1-1A R1-1B R2-2A R2-2B R3-3A R2-2 3GF 5
INDOOR OUTDOOR
Locations
VO
C C
on
ce
ntr
ati
on
s (
g
m-3)
Hexanal m,p-Xylene n-Propylbenzene Styrene Toluene
2.5
0.3
5.6
<0.1
<1.6
0246810
R2-2B 6A R2-2 3GF
INDOOR OUTDOOR
3.0
1.02.0
5.8
<0.1
0246810
R2-2B 6A R2-2 3GF
INDOOR OUTDOOR
Stationary Exp – Waiting at Crossing22 May 03
Adults waiting on the pavement are exposed to over 50% less particulate matter than if waiting in the central reservation – cyclical nature with traffic lights.
Children would be receiving a higher dose due to their proximity to the pollution source.