Meteorology, Air Quality, and Health in London: The ClearfLo Project

Abstract

The Clean Air for London (ClearfLo) project provides integrated measurements of the meteorology, composition, and particulate loading of the urban atmosphere in London, United Kingdom, to improve predictive capability for air quality. METEOROLOGY, AIR QUALITY, AND HEALTH IN LONDONThe ClearfLo Project Economic and Social Affairs 2013). Urban populations are exposed to stressful environmental conditions, such as local and nonlocal pollutants, that cause poor air quality and microclimates that exacerbate heat stress during heat waves. These are projected to increase in a warming climate. Our cities are therefore nexus points for several environmental health stresses that we currently face (Rydin et al. 2012) and the interacting issues around sustainability and human health.The purpose of this paper is to introduce the Clean Air for London (ClearfLo) project, which investigates the atmospheric science that underpins these health stresses, with a particular focus on the urban increment in atmospheric drivers. We focused on three atmospheric drivers of environmental health stress in cities, namely, heat, gas-phase pollutants, and particulate matter (PM). Health stresses from the urban atmospheric environment.Heat waves have an impact on human health. Populations typically display an optimal temperature range at which the (daily or weekly) mortality rate is lowest. Mortality rates rise as temperatures exceed this optimal range (e.g., Rydin et al. 2012). The 2003 European heat wave (Stedman 2004) in combination with air pollution was responsible for more than 2000 excess deaths in the United Kingdom (Johnson et al. 2005). Under a warming climate, the risks posed by heat stress are predicted to increase (Hacker et al. 2005). People living in urban environments are exposed to higher temperatures than in nonurban regions. Thus, heat-related deaths could be higher within urban areas (Mavrogianni et al. 2011). Hence, ClearfLo is concerned with measuring the factors controlling the urban atmospheric boundary layer, that is, the surface energy balance.The World Health Organization (WHO) reported (WHO 2006) that the strongest effects of air quality 779MAY 2015 AMERICAN METEOROLOGICAL SOCIETY | on health are attributable to PM, followed by ozone (O 3 ) and nitrogen dioxide (NO 2 ). A recent report (Guerreiro et al. 2013) indicates that in 2011 up to 88% of the urban population in Europe was exposed to concentrations exceeding the WHO air quality guidelines for PM 10 (defined as particles that pass through a size-selective inlet with a 50% efficiency cutoff at 10-µm aerodynamic diameter, representative of the inhalable fraction). It is estimated that a reduction of PM 10 to the WHO annual-mean guideline of 20 µg m −3 would reduce attributable deaths per year in Europe by 22,000. Further, this would lead to a substantial improvement in the quality of life for millions with a preexisting respiratory or cardiovascular disease (COMEAP 2010).Epidemiological studies consistently demonstrate an association between the PM mass concentr...

Air quality simulations for London using a coupled regional-to-local modelling system

“…Model simulations of NO x , NO 2 , O 3 , CO, PM 10 and PM 2.5 using the coupled system are compared with the regional and urban models run separately and with measurements from background and near-road sites across London for 2012. This choice of base modelling year has allowed detailed assessment of the model chemistry schemes with the ClearfLo summer and winter intensive observation data (Bohnenstengel et al, 2015;Malkin et al, 2016). During the summer of 2012 London hosted the Olympic and Paralympic Games, but no effects from the games' periods were apparent in a comparison of modelled and monitored concentrations at the monitoring site closest to the Olympic Park (now Queen Elizabeth Olympic Park).…”

“…In addition, short-term intensive campaigns making use of specialist monitoring equipment, as for example carried out for the ClearfLo project (Clean Air for London; Bohnenstengel et al, 2015), are of great value for detailed assessment of model performance and underlying processes, whilst sampling equipment can also be carried by moving vehicles or individuals for short-term detailed studies. In contrast to measurements, air quality or atmospheric chemistry transport models, evaluated with the above data, allow pollutant concentrations to be simulated with complete spatial-temporal coverage leading to detailed calculations of population exposure (Smith et al, 2016).…”

Socio-economic Impacts—Urban Climate

“…Sources of PM 10 in London depend on the weather pattern and comprise local sources and advection from within the UK and Europe. First results by the ClearfLo campaign measuring the composition of particulate matter in 2011 and 2012 in London at an urban background site suggest that organic aerosol is the most abundant (35 % of the total) followed by secondary inorganic aerosols such as nitrate (18 %), sulphate (11 %) and ammonium (9 %), and smaller contributions from marine aerosol components such as chloride (7 %) and sodium (4 %), and combustion emissions such as elemental carbon (Bohnenstengel et al 2015). Early analysis indicates that local London emissions have a bigger impact in winter when the lower boundary layer enables a build-up of primary pollutants.…”

Modelling carbonaceous aerosol from residential solid fuel burning with different assumptions for emissions

“…Model-measurement comparisons of a range of gaseous and particulate pollutants (Ots et al, 2016a) show that modelled concentrations of SFOA at the North Kensington site in London are substantially underestimated (normalised mean bias, NMB, of −71 %) compared to an annual dataset of PMF apportionment of AMS measurements collected during the 2012 Clean Air for London campaign (ClearfLo; Bohnenstengel et al, 2014;Young et al, 2015a;Xu et al, 2016). The aim of this work is to use these measurements of SFOA as the basis for an atmospheric chemical transport model exploration of potential closure of this discrepancy.…”