AGS Members' Day 2015 Designed Measuring Fibre Release, Richard Ogden

1. Measuring Fibre Release:
Post-development Risk Assessment
and Evaluation
(Construction-phase risks may differ)
Dr Richard Ogden
Land Quality Management Ltd

2. LQM and asbestos
• Renowned knowledge of contaminated land
assessment, management and remediation
• Track record of using detailed risk assessments to
avoid unnecessary remediation
– saving public and private sector large sums of money
• Several projects relating to asbestos-containing soils
(under planning and Part 2A)
• Authors (together with asbestos-specialists from
IOM) of the recent Ciria C733

3. Cards on the table….
• Are SUBSTANTIAL concentrations of airborne fibres
released from UK soils and made ground?
– We don’t know
• Do asbestos-containing soils pose a MATERIAL risk in
the UK?
– We don’t know
• Do small amounts of asbestos (particularly
chrysotile) in soils justify the current REMEDIATION
costs?
– We don’t know

4. Where is the uncertainty?
• Mainly, in exposure estimation
– Under what, if any, conditions are airborne fibres released from ACS in
the UK?
• Weather conditions, depths, activities
• Desiccation on hard surfaces
– What, if any, is the relationship between soil and airborne fibre
concentrations?
• How does it vary for different soils and made ground types?
– How much ACS be ‘tracked back’ into homes and offices?
– How quickly will ACMs release free fibres into soils? Does AC in soil
pose any risk?
• Internationally recognised problem

5. Can airborne fibres be released from
soils?
Theoretically, yes!
• Addison et al. (1988) proved that
airborne fibres can be released
– vigorous disturbance
– dry soils (<10% moisture)
– Asbestos fibres not ACM
• We know that surface soils can
dry out
– Especially where soil/mud
desiccates on roads, paths and
patios etc.
• QED airborne fibres could be
released
But there is ‘no’ proof!
• Only ~48 measurements in 3
types of soil
• Very little real-world data
– ‘Lot’s’ of Airborne fibres rarely
detected at construction sites
• How often do surface soils really
dry out?
• What is the effect of
vegetation/turf?
• QED would any exposure ever
really be significant?

6. Are airborne fibres ever released from soil/made
ground?
But what about
Domestic gardens?
School playing fields?
Public parks?
Etc….
Very little data to prove
that potential
exposures can or
cannot be significant

7. Existing air monitoring data
• Most current measurements (in the UK and elsewhere) are
made during construction activities
• Are they representative of post development conditions?
– Health and safety provisions eg damping down in dry weather (
exposures)
– Large disturbance of soil ( exposures)
– Fibre types not determined
– Soil concentrations not well understood
– Measurements below LoD required by CAR (0.1 or 0.01 f/ml) usually
assumed to be zero/acceptable/safe.
• But long-term exposures at, or below, these levels could pose
unacceptable risks (especially for amphiboles)

8. Dutch dataset:
Lab vs field measurement?
Average airborne asbestos concentrations from several comparable measurements (symbols) in
fibres/m3air and 95% confidence intervals (hyphens), from worst case simulation experiments (), from
field measurements with friable () and bound () asbestos, as a function of asbestos concentration in
soil. Straight lines represent the 95% intervals of all data. (After Swartjes & Tromp, 2008)
“measurement conditions were frequently not
well defined and the soil was often (made)
damp, on account of which relatively
‘favourable’ conditions (suppression of fibre
emission) prevailed.” Swartz et al (2003)

9. International questions (and possible
solutions)
• These uncertainties are widely acknowledged
• Even in countries with published frameworks/ policy on
asbestos-containing soils, including:
– Netherlands, Australia and USA
• Solutions and approaches:
– Ongoing research
– Development of novel soil sampling and testing methods that
better represent potential fibre release rather than asbestos
concentration
– Flexible policy frameworks
– Sharing of information

10. Is ABS a gold standard?
Photos: www.epa.gov
Activity-based sampling
USEPA’s preferred method at
“superfund” sites
Measures actual airborne
fibre concentrations under
“reasonable worst case
conditions”
Discriminate fibre types?
Compatible with CAR2012?
“prevent the exposure to asbestos
of any employee … so far as is
reasonably practicable; ”
Only possible at existing
property or post-development
Applicability under planning?

11. Estimate fibre release in the lab?
• The uncertainty in the relationship between soil and airborne
concentrations has led to interest in novel “fibre release
potential” tests
• More useful data for risk assessment than asbestos in soil
concentrations
• Usually involve:
– Mechanical disturbance of dry soil/made ground samples
– Airborne fibres collected on filter
– Asbestos fibres counted (and identified) oftn expressed relative to
dust concentrations (ie f/ml per mg m3 dust)

12. USEPA:
Fluidised bed asbestos segragator
• Air elutriation separates fibres from soil,
fibres collected on filter and analysed by
electron microscopy
• Approximately linear relationship between
the concentration of asbestos in soil (%)
and the mean concentration estimated by
FBAS/TEM (asbestos structures per gram
of test material)
• LoD 0.002-0.005%
• Components are easy to decontaminate or
disposable
• Development ongoing
Januch et al (2013) Anal. Methods (5) 1658

13. UK: HSL’s “dustiness test”
Based on BS EN15051:2006
Sample placed in rotating drum.
Air from the drum passes
through a filter which is
analysed for asbestos fibres
Results expressed as f/ml per
mg/m3 dust
Has been used in conjunction
with real-time dust
measurements to estimate
airborne fibre emissions during
soil remediation involving
mechanical screening
Images from Hardaker (2009) “Risk Assessment of Asbestos-Contaminated
Soils: An International Perspective” http://www.churchilltrust.com.au

14. Australia: Asbestos in soil to air
assessment method
• On-site testing analysis by
optical microscopy
• ASSAM prototype
developed to complement
conventional sampling in
– delineating free asbestos
contamination
– Determine if an exposure
pathway exists and trigger
further assessment
– Validate remedial works
Presented by Benjamin Hardaker (AECOM) at CleanUp 2013
http://www.cleanupconference.com/

15. Ongoing UK initiatives:
Including those by JIWG and
SoBRA
Based on presentation from Simon Cole at
Ciria “Risk Assessment and Management of
Asbestos in Soil” Conference, Manchester
January 2015

16. EIC-CL:AIRE Joint Industry Working
Group (JIWG)
• Survey of background in surface soils
– Industry & Defra funding
– Urban, semi-rural and rural soils in England & Wales
– Analysis by specially validated PCM method to
0.0001% w/w; replicate SEM analysis on a selection of
samples
• Standardised “Blue book” method for
quantification of asbestos in soils
– Publication shortly

17. EIC-CL:AIRE Joint Industry Working
Group (JIWG)
• Occupational risk assessment:
– Re-write Managing Asbestos (L143) to apply to
ACS
– Risk scoring algorithm to assist with CAR risk
assessments relating to ACS
• But also risk ranking public and environmental
exposures
• Similar framework to algorithms in HSG227 & 264 for
surveying and sampling buildings
• Excel based

18. SoBRA support for JIWG
• Focus on soil-air relationship
• Including:
– Review RIVM empirical data
– Open-access database for field measurements of
fibre and dust
• Soil and dust/fibre measurement protocols
– CAR-compliant Activity-Based Sampling protocol
• SoBRA outputs will be freely available

19. Conclusions
• Lab studies suggest that asbestos-containing soils could pose
unacceptable risks (particularly for amphiboles)
– significant uncertainties in current exposure estimation methods
– Precautionary approaches = unnecessary remedial costs?
• Internationally recognised issue
• Better knowledge of the Soil-air relationship is needed
– ABS is not always possible (particularly for redevelopment)
– International efforts to develop more informative soil tests to indicate
the potential for fibre release are ongoing
– Could radically simplify risk assessment and remedial costs at most
sites (ie lower risk with asbestos cement/chrysotile present)