Examination of Witnesses (Question Numbers
40-56)
DR IAN
S MCCRAE
9 FEBRUARY 2010
Q40 Dr Turner: What about the contribution
of brake and tyre wear towards air quality, particularly PMs?
Dr McCrae: Brake and tyre wear
is very important and it is one of the areas which has received
very little work over many years. All the products of abrasion—so
this is brake, tyre and road surface abrasion—are very significant
in terms of the generation of PM10 concentrations to the roadside
location. For me, the weakness in those is that we have some data
on brake and tyre wear but it is relatively weak in relation to
what we might consider more robust data for the conventional pollutants
coming from motor vehicles where we have a fair amount of data.
It is an area which has an immense paucity of information. One
of the key areas where there is virtually no information is on
the abrasion of the road surface which can be very important.
Added to those three abrasion products of tyre, brake and wear,
one of the key parameters that we need to think about is the re-suspension
of particulate matter. This is particulate matter which is lying
on the surface of the road which is entrained in the vehicle's
wake and causes a cloud behind the vehicle, and that can contribute
to roadside concentration of between a very small figure—a
single percentage figure—up to almost 60 or 70% of roadside
concentration. That is a great uncertainty; it could be a very
small component or it could be a major component of a roadside
concentration.
Q41 Dr Turner: Is that what you would
describe as secondary particulate matter? Do you think transport
actually contributes to that?
Dr McCrae: Secondary particulate
matter is normally something formed in the atmosphere, so it is
some of the compounds like ammonium sulphate and those sorts of
particulate compounds. It is a secondary source of particles in
that it is not directly emitted from the exhaust pipe in terms
of brake and tyre wear, so it could be classified as a secondary
source of particles. It is not legislated anywhere in terms of
seeking reductions in emissions of that sector. Whereas exhaust
emissions are regulated, emissions from tyres, breaks and road
surface are not regulated.
Q42 Dr Turner: I take it that your
laboratory has a research programme on vehicle pollution, particularly
particulates. Can you tell us a little about it?
Dr McCrae: We are a project-based
organisation so we compete in the market for research projects.
Over the last few years our main ones have been looking at generating
new emission factors for road transport. That is a fairly major
programme, pulling in information from across Europe in terms
of maximising the sample sizes and from those generating emission
factors for road transport for all different types of vehicle
classes. We have also done fundamental work on brake and tyre
wear, working largely in relationship with funding from the European
Community in terms of these multi-partner projects which you do
need to generate the sorts of sample sizes that you want within
the experimental domain.
Q43 Dr Turner: Has that offered any
options for reducing brake and tyre wear?
Dr McCrae: We are not actually
at that stage. What we have been trying to do is to categorise
the contribution of those sectors—brake, tyre and road surface
wear—to total particulate emissions and, therefore, trying
to use that data to inform the inventory developments which can
then be used to put weight on targeting the policies for reducing
particular sectors which are the most important.
Q44 Martin Horwood: In the context
of climate change mitigation we are also talking about the shift
towards electric vehicles and hydrogen-powered vehicles and so
on. Clearly these will still have brakes and tyres, so that kind
of matter will still be an emission, but would you expect that
to have a very dramatic impact on emissions from vehicles generally?
Have you done any work on this?
Dr McCrae: At the point of use
emission there will be significant improvements from moving towards
electric vehicles. If you look at something like a hybrid vehicle
we are looking at something like a 30% reduction in emissions
from tailpipe pollutants and, indeed, a 30% improvement in fuel
consumption. As you move towards fully electric vehicles obviously
at point of use the emissions are moving down towards zero, other
than those sources which are not coming from the tailpipe which
are things like the abrasion products.
Q45 Martin Horwood: Although the
shift is happening largely for other reasons it could have an
extremely dramatic impact on air quality.
Dr McCrae: I think it could. There
is obviously always a caveat on these issues and the big caveat
is that the electricity or the power has to be generated somewhere
and, therefore, we would want to combine with those sorts of policies,
if we want air quality improvements, a move towards that sort
of de-carbonisation of the power generation industry.
Q46 Mr Caton: Moving on to the role
of local authorities in tackling air quality, how successful has
local air quality management been?
Dr McCrae: The local air quality
management process, I guess, was triggered by the Environment
Act some years ago and what Defra did within that process was
to cascade much of the responsibility for the measurement—in
this case it was referred to as review and assessment of air quality—to
local authorities. That has been fairly successful. If you want
to look at local air quality you need to engage with local authorities
who understand the local area and the local sources and, indeed,
in much of the work done by local authorities you do not have
to have complex models and so forth to identify hotspots because
most local authority practitioners would actually know where the
major areas of concern are across their networks. I think it has
been quite a successful process. As you might expect I have a
small caveat on that, and that is to do with the fact that local
air quality management is about reviewing, assessing and measuring
something which is no help in terms of improving air quality.
What you need to do for that is to generate actions that will
improve air quality and the review and assessment process has
to develop an action plan, but what I see as one of the weaknesses
in that is not the development of the action plan per se but the
funding of the initiatives within an action plan are often relatively
weak so the money available to actually implement those changes
which seem sensible often do not see themselves in the network
because of lack of resources, and that is both staff time in local
authorities but also finances.
Q47 Mr Caton: So is that a failure
to give proper priority to the issue that is stopping councils
developing air quality management strategies or setting up low-emission
zones in your opinion?
Dr McCrae: My feeling is that
local authorities and central government spend a long time developing
the strategies. As a researcher, one of the things I see as a
weakness is the lack of assessment of those strategies in terms
of their effectiveness and that is not some instant thing, it
needs some research to go on to actually look at assessing what
are the most efficient measures to improve air quality, but then
also, once we have identified a few of those measures, to actually
have them implemented in the network does require financing. I
think that is one of the weaknesses in the whole process. At the
end of a review and assessment process the weakness is a lack
of resources to implement action plans.
Q48 Mr Caton: Do councils have access
to adequate information to monitor and improve their policies
in air quality?
Dr McCrae: I think my own feeling
is that local authorities have too much information. There is
an immense amount of literature and information on the mechanisms
of review and assessment; it is a very process-orientated system
of measuring, assessing, modelling and reporting. Combined with
that there are then all the various help desks which are available
to local authorities to try and respond to particular questions
that they may have on moving things forward with implementation.
Then there are a whole range of technical reports from a range
of bodies, including the reports from the air quality expert group
that went some way to try to inform local authorities about some
of the important issues in relation to particular pollutants.
Q49 Mr Caton: So as well as resourcing
that we have already mentioned, how could air quality management
best be improved at local level?
Dr McCrae: One of the complaints
we often hear from local authorities is the lack of integrated
work across government departments, so the difficulty engaging
with the various government departments that are essentially stakeholders
in that question, and they may be Defra, the Department for Transport,
the Highways Agency, the Environment Agency. All these agencies
need to be very joined-up providing very consistent advice to
local authorities. I think it is often difficult for local authorities
to seek that consensus from those bodies.
Q50 Joan Walley: You are talking
very much from the technical aspects in terms of TRL and looking
at the vehicle controls and pollution and so on. In terms of what
you have just said about local authorities, I am interested in
the planning aspect of this. You have said very clearly that you
think local authorities have got all this superb detailed expert
knowledge; I do not see much evidence from where I sit of what
they do with that because I do not see the transport officers
influencing planning decisions which tend to put the most polluting
operations in the most inappropriate places in residential areas.
Do you have any comments at all on the planning process?
Dr McCrae: It was not my intention
to imply that local authorities had all this knowledge; they have
the knowledge available to them. One of the problems with local
authorities is that the air quality staff within local authorities
often have to have several different hats so that air quality
may be something they are doing on a Monday and the rest of the
week they are looking after other disciplines within the environmental
health agenda, so air quality cannot be their only focus. That
is a problem in terms of the dilution of their resources. In terms
of the impact of planning legislation on air quality, it is a
key topic and it is one that needs more work to evolve over the
next couple of years to really have some teeth within that. There
have been some successful applications within the planning system
to aid air quality. To give an example, the London Borough of
Greenwich in the use of their section 106 agreements to try to
allocate money from developments to air quality issues has been
very successful and it is being rolled out across the country
in terms of how to do it and how to do it most effectively.
Q51 Joan Walley: Could you just elaborate
on what kind of benefits might come from section 106 in terms
of improving air quality?
Dr McCrae: Section 106 is an agreement
between a developer and a local authority to try to ring-fence
some money from the developer to support particular initiatives
that will improve local air quality in that particular case. It
may be as simple as re-designing a junction as part of the entry
to a new housing development or the local road network; it may
be other physical things like the support of air pollution modelling
activities. So you could use that money for various aspects to
support your air quality department within a local authority.
Q52 Joan Walley: Would you expect
every local authority to have an air quality monitoring department?
Dr McCrae: I would not. I would
expect them all to have an environmental health department and
a highways and transportation department and those two departments
need to talk to each other.
Q53 Joan Walley: You would expect
them to talk to each other, would you?
Dr McCrae: Yes. We do see that
quite successfully in many local authorities; there are some very
active negotiations between those two departments that many years
ago would not have spoken to each other.
Q54 Joan Walley: Could you perhaps
give us an example of local authorities where that kind of joint
working works well?
Dr McCrae: I think you see it
in departments in Leeds. Leeds City Council has very integrated
highways and environmental health teams.
Q55 Chairman: Increasingly, things
like emissions from engines are subject to regulation with some
success in reducing various kinds of polluting emissions. Do you
think it is possible to apply the same sort of regulatory approach
to particulate matter that is generated by tyres and brakes and
so on?
Dr McCrae: I am sure it is. In
terms of particulate matter generated by brakes, there could be
a way of enclosing the brake mechanism to limit the release of
particles at that point of generation. In terms of tyres, it seems
sensible to integrate within the whole idea of recycling of tyres
to improve their longevity in service which would help with the
recycling issue of tyres. Having said that, if you do make them
harder or stiffer then you can affect the running resistance associated
with tyres which is an important component of fuel consumption
of a vehicle. One needs to be careful in terms of generating legislation
on tyres for reduced particulate wear if it diminishes the rolling
resistance and, therefore, the grip of the tyre and if you influence
that in any way which could be associated with accidents.
Q56 Chairman: Thank you very much.
We have some more witnesses so we will have to move on to, but
thank you very much for your time this morning.
Dr McCrae: My pleasure.
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