The London Low Emission Zone Baseline Study

EPA Grant Number: R834677C163
Subproject: this is subproject number 163 , established and managed by the Center Director under grant R834677
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: Health Effects Institute (2010 — 2015)
Center Director: Greenbaum, Daniel S.
Title: The London Low Emission Zone Baseline Study
Investigators: Kelly, Frank
Institution: University of Cambridge , Health Effects Institute (HEI)
EPA Project Officer: Hunt, Sherri
Project Period: April 1, 2010 through March 31, 2015
RFA: Health Effects Institute (2010) RFA Text |  Recipients Lists
Research Category: Health Effects , Air Quality and Air Toxics , Air


The London Low Emission Zone (LEZ) baseline study is designed to conduct research aimed at evaluating whether regulatory and other actions taken to improve air quality have resulted in the intended improvements in air quality, exposure, and health outcomes.

The London LEZ was designed to improve air quality in Greater London by restricting entry of the oldest and most polluting vehicles in phases. Beginning in February 2008, heavy-duty diesel-engine vehicles and then other classes of vehicles would have to meet Euro III emissions standards and, by 2012, the more stringent Euro IV standards. Low emission zones, also known as environmental zones, have been implemented in countries all over the world. With coverage of about 2644 km2, the London LEZ is one of the largest and therefore provides an intriguing opportunity for research.

In planning their evaluation of the LEZ, Kelly and colleagues plan to build upon their earlier investigation of the air quality impacts of London’s Congestion Charging Scheme (CCS); they intend to study the potential impacts of the LEZ first on air quality and then on health using existing databases of electronic medical records from primary-care practices serving a majority of London residents. The Investigators intend to evaluate the feasibility of such a study by collecting baseline data before the LEZ went into effect and to develop methodological approaches.


The investigators will conduct detailed emissions and air pollution modeling. Using an LEZ scenario in which heavy-duty diesel-engine trucks and buses were required to meet Euro IV emissions standards for particulate matter (PM) and nitrogen oxides (NOx), they will project effects of the LEZ on the mix of vehicles entering the zone, their emissions, and air pollutant concentrations and compared them with those of a “base case” scenario, which assumed the LEZ had not been implemented. Specifically, they predicted total emissions and ambient concentrations of NO, nitrogen dioxide (NO2), PM with an aerodynamic diameter ≤ 10 μm (PM10) from exhaust, and PM10 from tire and brake wear throughout Greater London.

Using these projections, they will evaluate the existing air monitoring network; as a result of this assessment, Transport for London, which is responsible for London’s transport system, agreed to add or upgrade air pollution and traffic monitoring at seven key roadside locations. The final monitoring network available for study  will include 41 sites (28 roadside and 9 urban background sites within London and 2 roadside and 2 urban background sites outside London).

Using methods based on their earlier study of the London CCS, the investigators will study characteristics of PM that they hypothesized might explain its toxicity. They will examine the oxidative potential and the metal content in extracts from archived filter samples of PM10 and PM2.5 (PM with an aerodynamic diameter ≤ 2.5 μm) from the monitoring sites. Oxidative potential, an indicator of a compound’s ability to cause damage via chemical reactions, will be estimated using a cell-free in vitro assay (i.e., the synthetic respiratory tract lining fluid assay) developed by the team. The assay will measure the ability of filter extracts to deplete the levels of three common antioxidant compounds (ascorbate, reduced glutathione, and urate) found in the lungs. They will also analyze each filter extract for a panel of metals previously associated with exhaust or with tire and brake wear and assessed their possible contribution to oxidative potential.

The Investigators will assess the feasibility of obtaining and using electronic medical records from London’s primary-care practices to study possible health impacts of the LEZ. The records will come from two sources: the Doctors’ Independent Network and the Lambeth database, which together covered a total of 42 practices and about 300,000 patients. The investigators will  explore ways to classify practices according to predicted LEZ-related changes in pollutant concentrations while maintaining the confidentiality of patient data. Using NOx as an index pollutant, they conducted exploratory cross-sectional analyses of the relationships between exposure and indicators of respiratory and cardiovascular diseases and looked at potential confounding factors, such as socioeconomic status, ethnic background, and smoking. The investigators will then estimate the statistical power of future epidemiologic studies to detect changes in health outcomes associated with expected LEZ-related improvements in air quality.

Expected Results:

The investigators hope that the LEZ baseline study will present a creative effort to lay the groundwork for studying spatial and temporal changes in air pollutant concentrations and health outcomes in advance of a major regulatory intervention. It is hope that the study will provide important lessons for future research into the health outcomes of actions to improve air quality.

Relevant Websites: Exit

Main Center Abstract and Reports:

R834677    Health Effects Institute (2010 — 2015)

Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R834677C149 Development and Application of a Sensitive Method to Determine Concentrations of Acrolein and Other Carbonyls in Ambient Air
R834677C150 Mutagenicity of Stereochemical Configurations of 1,3-Butadiene Epoxy Metabolites in Human Cells
R834677C151 Biologic Effects of Inhaled Diesel Exhaust in Young and Old Mice: A Pilot Project
R834677C152 Evaluating Heterogeneity in Indoor and Outdoor Air Pollution Using Land-Use Regression and Constrained Factor Analysis
R834677C153 Improved Source Apportionment and Speciation of Low-Volume Particulate Matter Samples
R834677C155 The Impact of the Congestion Charging Scheme on Air Quality in London
R834677C156 Concentrations of Air Toxics in Motor Vehicle-Dominated Environments
R834677C158 Air Toxics Exposure from Vehicle Emissions at a U.S. Border Crossing: Buffalo Peace Bridge Study
R834677C159 Role of Neprilysin in Airway Inflammation Induced by Diesel Exhaust Emissions
R834677C160 Personal and Ambient Exposures to Air Toxics in Camden, New Jersey
R834677C162 Assessing the Impact of a Wood Stove Replacement Program on Air Quality and Children’s Health
R834677C163 The London Low Emission Zone Baseline Study
R834677C165 Effects of Controlled Exposure to Diesel Exhaust in Allergic Asthmatic Individuals
R834677C168 Evaluating the Effects of Title IV of the 1990 Clean Air Act Amendments on Air Quality
R834677C172 Potential Air Toxics Hot Spots in Truck Terminals and Cabs
R834677C173 Detection and Characterization of Nanoparticles from Motor Vehicles
R834677C174 Cardiorespiratory Biomarker Responses in Healthy Young Adults to Drastic Air Quality Changes Surrounding the 2008 Beijing Olympics