William Wong
Dissertation Proposal
Supervisor: Mat Disney
The effects of road transport on the Carbon Monoxide and Nitrogen
Oxides overtime between the areas of Central and Inner London.
Aims and objectives
The aims of this study is to find out how Carbon Monoxide (CO) and Nitrogen Oxides (NOx)
concentration is linked to the variation of road traffic in London over a period of time. The study
will also look at the difference in selected pollutant concentration and traffic flows between Inner
and Inner London. Because traffic flows are different between areas at Central London and
Inner London, the concentration of the selected pollutant may be different. I would also look at
whether regulated transport policies in the last few years made an impact on the selected
pollutant concentration in London.
I have made three research questions, which I will test to see whether my results can answer
each one of them. The research questions for this study are:
 At which time period does the CO and NOx concentration decrease dramatically in Central
and Inner London?
 Does the variation of traffic flow levels affect CO and NOx concentration over areas of
Central London and Inner London?
 Which pollutant’s concentration has been affected the most by London’s transport
regulation?
Context and previous work
CO and NOx concentration are generated by the burning of fossil fuels. The two main sources
that contribute to these two classical pollutants are burning fossil fuels for electricity generation
and road transport. It is important to study the relationship between CO and NOx pollutants and
transport because not only do both pollutant affect individual respiratory system (Glaister et al,
1999), but CO and NOx concentrations could be indirectly linked. When CO is emitted into the
atmosphere, it reacts with nitric oxide and oxygen to produce carbon dioxide and nitrogen
dioxide. If CO concentration increases, nitrogen dioxide would increase in the atmosphere,
which affects NOx concentration and increase the chances of photochemical smog formation
(Westberg et al, 1971).
According to London Research Centre (LRC) (1998), road transport contributes to 97% of CO
and 75% of NOx in Greater London 1995. Within these percentages, cars (petrol) contribute the
most to NOx (42%) and CO (88%) concentrations. In order to develop an effective regulation on
transport to reduce urban emissions, it is important to understand the amount of concentration
William Wong
Dissertation Proposal
Supervisor: Mat Disney
that road transport emits to the atmosphere and which type of vehicles contribute the most to
road traffic emissions (Holman, 1999). Apart from cars (petrol), other transport needs to be
taken into account (Lorries and diesel vehicles) because they contribute to the emissions of
London’s air pollution.
London Scientific Services created a report named “Air pollution associated with transport in
London”, which was published in 1990 for the London Planning Advisory Committee (LPAC,
1990). The report looks at nine different air pollutant including CO and NOx and relates their
concentration levels to the WHO guidelines in order to see if the pollutant levels are over the
limit. It looks at how different types of vehicles (e.g. HGV, Petrol cars) contribute to the various
pollutants that exist in London. LPAC looks at the pollutant levels in order to provide some
suitable strategies to manage pollution problem like the Luxembourg agreement (European
Community Council Directive, 1987) and technical improvement i.e. catalytic converts.
Small and Kazimi (1995) focused its research on six different air pollutants (CO, NOx, ozone,
SO2, VOCs and PM). The author looks into the cost of pollutant emissions by using direct
estimation of damages and tries to put a link between air pollution and adverse consequences
in relation to economic values. Rather than focusing on the link between the primary pollutants
and road transport, they take account of other features nearby that may affect the pollutants’
concentration such as the topography and atmospheric conditions. Los Angeles was used a s a
case study in this research, where they compare their air emissions result with human health
There is also a report on the transport and health of London by Glaister et al (1999), which was
researched for NHS executive. The report provides a very detailed analysis of accidents,
different air pollutants and mortality in relation to transport and providing solution to reduce the
issues in the report such as transport policies. In this report, my only interests are the air
pollutant and transport information and management because those are my focused area of
study.
The author concentrates on the five different air pollutants (Same as Small and Kazimi research
but they did not include ozone). The report looks at the chemistry of each pollutant, the source
of emission relating to transport and how it affects individual health. They collected secondary
data and used time-series analysis to link the concentrations with transport datasets. Using
these data, the author directly compares the results to the mortality figures in London to show
whether London’s air pollution is responsible for most health issues.
Glaister et al also looked at transport strategies mentioned in different research papers and
linking it to London’s current management. Transport management strategies and modelling
management regulation from other papers is essential to compare it effectiveness on controlling
traffic and if it is suitable to apply to London today (compared to congestion charge). Strategies
William Wong
Dissertation Proposal
Supervisor: Mat Disney
such as modelling of the outcome of CO2 if fuel tax were increase by 42% or car ownership
taxes were increased by 470% (Koopman, 1995).
My proposed dissertation would contribute to the research of this report by looking at the more
recent pollutant and transport records and comparing the Central London and Inner London
regions to further develop the LPAC report (1990). It would contribute to knowledge of current
pollutant level (CO and NOx) and show whether current transport regulation has made any
impacts on pollutant concentrations. The audience of my proposed dissertation would be the
public who are interested in traffic and air pollution as well as environmental agency and
Transport of London (Tfl). Organisation such as Environmental Agency and Tfl could use the
information and analysis on my dissertation to propose future management on transport and air
quality in London by comparing my results with future datasets. Apart from the future, my
dissertation is also useful to look into the effectiveness of current transport policies because Tfl
could improve their current regulation on transport, if the results of my dissertation do not make
a huge impact during the time of regulation.
Research methods
For my research, I will be collecting secondary data for transport and for pollutant
concentrations for CO and NOx. I chose to use secondary sources to collect my data because
there are existing recorded data sets for various pollutant and transport in different areas of
London. It is not necessary to collect the primary data when there are records of these data
available (from monitoring sites) (Sorensen et al, 1996) in areas such as Bloomsbury and
Bexley in London.
I have already collected online datasets for road traffic statistic and annual average daily flows
dating from 1993 to 2007, for all London councils from the Department of Transport (Dft).
Therefore, I will try to collect CO and NOx concentration datasets from 1993 to 2007 for direct
comparison. I have chosen to collect the datasets during this time period because I can
compare the selected pollutant concentration and transport data before and after the regulation
of Congestion Charge and Low Emission Zones. Therefore, finding NOx and CO datasets can
determine whether the regulation has made any impact on the concentrations.
William Wong
Dissertation Proposal
Supervisor: Mat Disney
I have also collected time series datasets for CO and NOx concentrations AEA (which is a part
of DEFRA) through the internet. However, AEA has datasets available for only seven regions
within London, where five regions are in Central London and the three remaining are located in
Inner London (See figure 1). Therefore, I am going to combine the online datasets from London
Air Quality Network (LAQN) with the AEA and select to produce an even comparison of ten
regions between Central and Inner London (Five monitoring sites in Central London and five
from Inner London area). The LAQN has 26 different sites that have recorded both NOx and CO
concentrations. Figure 1 would provide an outline to locate whether a monitoring site is located
in Central or Inner London area.
However, some regions do not contain data as far as 1993, which can be a problem when
comparing with traffic flow data since I have datasets from 1993 to 2007. This is one of the
potential problems that my study may encounter because there are specific monitoring sites that
does not have a record of past pollutant concentration available. So, there is a limited choice to
which datasets I could choose to compare. However, if I cannot find five monitoring sites for
Central and Inner London due to lack of recording dating back to 1993, then I will have to
reduce the time period (i.e. 1996 to 2007) in order to find available datasets to analysis.
William Wong
Dissertation Proposal
Supervisor: Mat Disney
Another problem that I may encounter during my study is the selection of monitoring sites to
represent the two areas. I will pick datasets from monitoring sites that are either in different
councils or that are not clustered together with other sites. Site selection is important because if
I use datasets from two monitoring sites that are clustered together, the recordings are likely to
be similar (See Figure 2). Figure 2 is an example map which shows where the monitoring sites
are location. Some CO monitoring sites on figure 2 is clustered close together. So, if I already
have a dataset for one of the monitoring sites in the clustered region, it is not necessary to have
another dataset taken from that region again. I would try and find sites that are located in North,
East, South and West London, in order to show how the selected pollutant concentration varies
at different geographical locations.
The LPAC report (1990) notes that stable weather conditions in London (with light winds and
clear skies) could trap vehicle emissions in a stable air mass near the ground. The weather
patterns during the recording of the pollutant concentration are unknown, so there may be
issues with the accuracy of these data from the monitoring sites. However, this issue is
minimised by using daily mean dataset because it would average out the variation of data which
may have been affect by the conditions of that weather during each day.
Data analysis
For my selected pollutant concentrations, I will be using Time-Series analysis on CO and NOx
concentrations on the 10 chosen sites. Because the dataset are recorded as daily mean, I will
have to change the daily mean datasets to monthly, in order to see the monthly variation of CO
and NOx concentration. The Time-Series graph allows detail analysis of the selected
concentration over a period of time. It provides a clear representation of the datasets that I have
collected at different monitoring sites.
William Wong
Dissertation Proposal
Supervisor: Mat Disney
Pollutant Concentration Maps would also be used to show CO and NOx concentration across
London. To generate this map, the monthly datasets will be added up to produce yearly data.
The reason for using yearly data is because I want to visually analyse how the selected
pollutant changes before and after transport regulation in London. The GIS points should be
located on the website of AEA or LAQN, which I can use to find the monitoring site location on
the pollutant concentration map. If they are not located on the site, I will email AEA and LAQN to
provide the GIS location points.
Linear regression will be used to compare traffic daily flow and CO and NOx concentrations.
The reason for using linear regression on these dataset is because it would show the
relationship between the traffic flow data and selected pollutant concentration. This will also be
used to analyse how management strategies on transport has affected the concentration levels
of CO and NOx e.g. 2003 with the London Congestion Charge (Tfl (1), 2006).
Ethics
The ethical issue this study may contain is the use of secondary data from various
organisations. Eventhough the data I have collected and will be collecting is available on the
internet, but the organisation who distributes would not like the users to assign these data to
third party without their consent. Therefore, I will send a copy of a completed dissertation to
each organisation who I have used the dataset for my study. These organisations include the
Department of Transport, AEA and NAEI (who are on behalf of DEFRA).
Expected outcomes and significance
The results from my study are expected show a link between transport and CO and NOx. Over
time, as car ownership in UK increases from population increase, CO and NOx concentration
will still be an environmental issue in London (Dft, 1997). I predict that the selected pollutants
concentration should decrease dramatically after 2003 because London introduced congestion
charge in 2003, which would reduce the amount of road vehicles users promote use alternative
transport such as trains. This information is useful to the readers who are environmentalist or
organisation such as AEA because this research question could show London’s pollutant
concentrations changes over time. It could also be used to link with other pollutant levels that
may be affected indirectly such as Ozone.
There should be a high variation between the traffic flow of Central and Inner London because
most of the public transport and busy roads are located near the centre of London. Since most
services are located in Central London and residential areas are mainly found in Inner London,
the data are expected to show high daily traffic flow in Central London and Low daily traffic flows
in Inner London. Therefore, CO and NOx concentration should be lower in Inner London than
Central London. However, the results for this research question may be affected by commuter
William Wong
Dissertation Proposal
Supervisor: Mat Disney
travelling from areas outside of Greater London. I may expect high levels of NOx and CO
concentrations at the West of London because around 60%-80% of commuters from West of
Greater London drive into the city by car (40%-60% around the other areas) (Tfl (2), 2006). The
outcome of this research question would provide the audience useful information to which areas
of London produces the most pollutant concentration of CO and NOx. Organisation such as Tfl
could create new regulations for those areas to reduce traffic flow across the high CO and NOx
concentration areas.
CO concentrations should be affected the most when transport regulation is introduced. Road
transport contributes a higher percentage of CO in London than NOx (LRC, 1998), which means
the regulation on transport should reduce CO concentration more than NOx in London. The
outcome of this research question allows the organisations such as Tfl to take account of which
pollutant would be affected the most by transport regulation. This would show whether their
regulation such as Low emission zone in central London (Tfl, 2004) has taking any effect on CO
and NOx concentrations and if more regulation is needed to reduce the concentrations.
References
Atmospheric Research and Information Centre (ARIC) “Atmosphere, Climate & Environment
Information Programme Factsheet 4: The Key Air Pollutants”, Manchester
Metropolitan University
Glaister et al, (1999) ‘Transport and Health in London: a report for the NHS executive, London’,
London, Mayor of London:
“http://www.london.gov.uk/lhc/docs/lhs/rapidreviews/transport.pdf”
Koopman, GJ (1995) ‘Policies to reduce CO2 emissions from cars in Europe: a partial
equilibrium analysis’, Journal of Transport and Economics and Policy, 29, 1, 53-70
London Air Quality Network (LAQN) - Environmental Research Group, King's College London:
“http://www.londonair.org.uk/”
London Planning Advisory Committee (LPAC) (1990) Airpollution associated with transport in
London, Romford, LPAC
London Research Centre (LRC) (1998) Greater London Atmospheric Emissions Inventory,
London, LRC
William Wong
Dissertation Proposal
Supervisor: Mat Disney
Small, K.A and Kazimi, C (1995) ‘On the costs of air pollution from motor vehicles’, Journal of
Transport Economics and Policy, 29, 1, 7-32
Sørensen et al, (1996) ‘A Framework for Evaluation of Secondary Data Sources for
Epidemiological Research’, International Journal of Epidemiology, 25, 2, 435-442
Tfl (Transport of London) (2004) ‘The Low Emission Zone Cleaner air for Greater London’,
Transport of London:
http://www.tfl.gov.uk/assets/downloads/LEZ/LEZ-information-leaflet.pdf
Tfl (1) (2006) ‘Congestion Charge Four Year Programme’, Mayor of London:
http://www.tfl.gov.uk/assets/downloads/Four_Year_Programme_2006.pdf
Tfl (2) (2006) ‘London Travel Report 2006’, Mayor of London:
“http://www.tfl.gov.uk/assets/downloads/corporate/London-Travel-Report-2006final.pdf”
Westberg et al, (1971) ‘Carbon Monoxide: Its Role in Photochemical Smog Formation’, Science,
171, 3975, 1013-1015
Wikipedia (2005) Central London, Central London and Inner London:
“http://en.wikipedia.org/wiki/Central_London”