Urban air pollution modelling with machine learning using fixed and mobile sensors

Detailed air quality (AQ) information is crucial for sustainable urban management, and many regions in the world have built static AQ monitoring networks to provide AQ information. However, they can only monitor the region-level AQ conditions or sparse point-based air pollutant measurements, but cannot capture the urban dynamics with high-resolution spatio-temporal variations over the region. Without pollution details, citizens will not be able to make fully informed decisions when choosing their everyday outdoor routes or activities, and policy-makers can only make macroscopic regulating decisions on controlling pollution triggering factors and emission sources. An increasing research effort has been paid on mobile and ubiquitous sampling campaigns as they are deemed the more economically and operationally feasible methods to collect urban AQ data with high spatio-temporal resolution. The current research proposes a Machine Learning based AQ Inference (Deep AQ) framework from data-driven perspective, consisting of data pre-processing, feature extraction and transformation, and pixelwise (grid-level) AQ inference. The Deep AQ framework is adaptable to integrate AQ measurements from the fixed monitoring sites (temporally dense but spatially sparse), and mobile low-cost sensors (temporally sparse but spatially dense). While instantaneous pollutant concentration varies in the micro-environment, this research samples representative values in each grid-cell-unit and achieves AQ inference at 1 km \times 1 km pixelwise scale. This research explores the predictive power of the Deep AQ framework based on samples from only 40 fixed monitoring sites in Chengdu, China (4,900 {\mathrm{km}}^\mathrm{2}, 26 April - 12 June 2019) and collaborative sampling from 28 fixed monitoring sites and 15 low-cost sensors equipped with taxis deployed in Beijing, China (3,025 {\mathrm{km}}^\mathrm{2}, 19 June - 16 July 2018). The proposed Deep AQ framework is capable of producing high-resolution (1 km \times 1 km, hourly) pixelwise AQ inference based on multi-source AQ samples (fixed or mobile) and urban features (land use, population, traffic, and meteorological information, etc.). This research has achieved high-resolution (1 km \times 1 km, hourly) AQ inference (Chengdu: less than 1% spatio-temporal coverage; Beijing: less than 5% spatio-temporal coverage) with reasonable and satisfactory accuracy by the proposed methods in urban cases (Chengdu: SMAPE \mathrm{<} 20%; Beijing: SMAPE \mathrm{<} 15%). Detailed outcomes and main conclusions are provided in this thesis on the aspects of fixed and mobile sensing, spatio-temporal coverage and density, and the relative importance of urban features. Outcomes from this research facilitate to provide a scientific and detailed health impact assessment framework for exposure analysis and inform policy-makers with data driven evidence for sustainable urban management.Open Acces

“Exposure Track”—The Impact of Mobile-Device-Based Mobility Patterns on Quantifying Population Exposure to Air Pollution

Air pollution is now recognized as the world’s single largest environmental and human health threat. Indeed, a large number of environmental epidemiological studies have quantified the health impacts of population exposure to pollution. In previous studies, exposure estimates at the population level have not considered spatially- and temporally varying populations present in study regions. Therefore, in the first study of it is kind, we use measured population activity patterns representing several million people to evaluate population-weighted exposure to air pollution on a city-wide scale. Mobile and wireless devices yield information about where and when people are present, thus collective activity patterns were determined using counts of connections to the cellular network. Population-weighted exposure to PM2.5 in New York City (NYC), herein termed “Active Population Exposure” was evaluated using population activity patterns and spatiotemporal PM2.5 concentration levels, and compared to “Home Population Exposure”, which assumed a static population distribution as per Census data. Areas of relatively higher population-weighted exposures were concentrated in different districts within NYC in both scenarios. These were more centralized for the “Active Population Exposure” scenario. Population-weighted exposure computed in each district of NYC for the “Active” scenario were found to be statistically significantly (p < 0.05) different to the “Home” scenario for most districts. In investigating the temporal variability of the “Active” population-weighted exposures determined in districts, these were found to be significantly different (p < 0.05) during the daytime and the nighttime. Evaluating population exposure to air pollution using spatiotemporal population mobility patterns warrants consideration in future environmental epidemiological studies linking air quality and human health

Towards high spatial resolution air quality mapping : a methodology to assess street-level exposure based on mobile monitoring

Exposure to air pollution has a severe impact on human health. Especially in urban areas, where most of the European population lives and which are typically hot-spots of air pollution, a lot of people are exposed to air pollution. However, the urban environment shows a high variability in air pollutant concentrations and available data are often lacking to accurately estimate the actual concentration levels citizens are exposed to. The emergence of lower-cost and portable sensors makes it possible to perform mobile measurements and to collect additional data at locations where stationary measurements are lacking. Further, this also makes it possible to engage citizens in participatory monitoring techniques. However, several issues on spatial and temporal representativeness can interfere with the real-life applicability of mobile monitoring. This thesis presents the possibilities and challenges of the use of mobile data to map the urban air quality. Based on an extensive targeted campaign, it is shown that mobile monitoring is a suitable approach to map the urban air quality at a high spatial resolution when using a carefully developed methodology. However, a large number of repeated measurements are still required to obtain representative results. A possible way to gather a large number of measurements is to make use of people’s common daily routines to move measurement devices around, which is defined as opportunistic measurements. An example case study with the collaboration of the city wardens of Antwerp is presented in this thesis. Mobile monitoring typically does not yet result in city-wide pollution maps. Based on the data, regression models can be built to predict the concentration levels at other locations. The results highlighted the potential to construct near-real-time pollution maps that can be used for providing personalized information about air quality to citizens

Next Generation Air Quality Platform: Openness and Interoperability for the Internet of Things

The widespread diffusion of sensors, mobile devices, social media, and open data are reconfiguring the way data underpinning policy and science are being produced and consumed. This in turn is creating both opportunities and challenges for policy-making and science. There can be major benefits from the deployment of the IoT in smart cities and environmental monitoring, but to realize such benefits, and reduce potential risks, there is an urgent need to address current limitations including the interoperability of sensors, data quality, security of access, and new methods for spatio-temporal analysis. Within this context, the manuscript provides an overview of the AirSensEUR project, which establishes an affordable open software/hardware multi-sensor platform, which is nonetheless able to monitor air pollution at low concentration levels. AirSensEUR is described from the perspective of interoperable data management with emphasis on possible use case scenarios, where reliable and timely air quality data would be essential.JRC.H.6-Digital Earth and Reference Dat

Urban air quality citizen science. Phase 1: review of methods and projects

This report will comprise suggestions of links with other work and possible approaches for taking the work forward, providing a map of current and recent air quality related Citizen Science activities in the UK, Europe and beyond. In this deliverable, we map out the technologies and approaches currently available for air quality monitoring and provide an overview on how they could be applied in a citizen science context. In addition, we provide an overview of existing citizen science activities with relevance to air pollution. The focus of this report will be on the specific aspects of air pollution monitoring in a citizen science context; we refer to Roy et al. (2012) for a more general discourse on citizen science projects. As far as possible, we will closely link to another SEPA funded project with a focus on citizen science for environmental monitoring (by direct personal contact with colleagues at CEH), as well as other ongoing and emerging projects (e.g. EU FP7 project CitiSense, Transport Scotland, etc.). The objective of this report is not to draw final conclusions, but to provide the material and information resources for the following phases 2 and 3 of the pilot project

Integrating modelling and smart sensors for environmental and human health.

Sensors are becoming ubiquitous in everyday life, generating data at an unprecedented rate and scale. However, models that assess impacts of human activities on environmental and human health, have typically been developed in contexts where data scarcity is the norm. Models are essential tools to understand processes, identify relationships, associations and causality, formalize stakeholder mental models, and to quantify the effects of prevention and interventions. They can help to explain data, as well as inform the deployment and location of sensors by identifying hotspots and areas of interest where data collection may achieve the best results. We identify a paradigm shift in how the integration of models and sensors can contribute to harnessing 'Big Data' and, more importantly, make the vital step from 'Big Data' to 'Big Information'. In this paper, we illustrate current developments and identify key research needs using human and environmental health challenges as an example.E.S. is funded by NIH R21ES024715. M.C. gratefully acknowledges the Minnesota Discovery, Research and InnoVation Economy (MnDRIVE) “Global Food Venture” funding and the Institute on the Environment “Discovery Grant” funding at the University of Minnesota Twin-Cities. S.R. and S.S. acknowledge the support for the conceptual development and testing of personal exposure monitoring methods by the UK Natural Environment Research Council through National Capability funding.This is the final version of the article. It was first available from Elsevier via http://dx.doi.org/10.1016/j.envsoft.2015.06.00

Towards unravelling the relationship between on-body, environmental and emotion data using sensor information fusion approach

Over the past few years, there has been a noticeable advancement in environmental models and information fusion systems taking advantage of the recent developments in sensor and mobile technologies. However, little attention has been paid so far to quantifying the relationship between environment changes and their impact on our bodies in real-life settings. In this paper, we identify a data driven approach based on direct and continuous sensor data to assess the impact of the surrounding environment and physiological changes and emotion. We aim at investigating the potential of fusing on-body physiological signals, environmental sensory data and on-line self-report emotion measures in order to achieve the following objectives: (1) model the short term impact of the ambient environment on human body, (2) predict emotions based on-body sensors and environmental data. To achieve this, we have conducted a real-world study ‘in the wild’ with on-body and mobile sensors. Data was collected from participants walking around Nottingham city centre, in order to develop analytical and predictive models. Multiple regression, after allowing for possible confounders, showed a noticeable correlation between noise exposure and heart rate. Similarly, UV and environmental noise have been shown to have a noticeable effect on changes in ElectroDermal Activity (EDA). Air pressure demonstrated the greatest contribution towards the detected changes in body temperature and motion. Also, significant correlation was found between air pressure and heart rate. Finally, decision fusion of the classification results from different modalities is performed. To the best of our knowledge this work presents the first attempt at fusing and modelling data from environmental and physiological sources collected from sensors in a real-world setting

mHealth Geographies: Mobile Technologies and Health in the Global South

This is the author accepted manuscript. The final version is available from Routledge via the URL in this record