Metrology to exploit low-cost sensor networks for applications in air quality and energy management

Lead Research Organisation: University of Surrey
Department Name: Civil and Environmental Engineering


Air pollution is a global problem, but due to its highly localised nature we know very little about the health effects on the individual. The UK currently has numerous reference standard air quality networks including the AURN and LAQN, but these networks have a relatively low spatial resolution and time frequency in order to meet EU Air Quality directives. In order to obtain real time data with a dense network, we need an alternative. This project focuses on low cost air quality sensor systems, designed to look at a range of pollutants including nitrous oxides, ozone, carbon monoxide and particulates. These low-cost sensor systems are advantageous, as their low price point allows many of them to be deployed over a short area, giving very dense air pollution data without requiring both the monetary and labour investment that reference equipment requires.
However, there are several limitations with this technology. The low-cost nature of these systems leads to many problems with the measurement value drifting from the real value. Degradation of the sensor components over time can lead to the initial calibration of the sensor becoming inaccurate, as well as changes in environmental conditions causing the measurement value to drift. These drifts are difficult to account for in lab-based testing as covering all possible concentrations, temperatures, humidity levels and cross-pollutant levels would be a massive undertaking and would most probably result in the cost advantage of the systems being removed. For this reason, calibration techniques must be employed that can account for the range of conditions the sensors will face.
This project aims to focus not just on the calibration of these sensors to account for these environmental conditions, but also develop techniques to maintain the calibration for as long as possible by detecting and quantifying the drift. There are currently no agreed upon standards for both calibrating low-cost sensors and determining whether they have drifted, so this project will explore several different techniques in an effort to determine the most effective ones. A test network will be deployed at the University of Surrey Guildford campus with a focus on collecting high resolution data, followed by possible further networks being set up in Delhi and Sao Paulo.
This project will be undertaken in collaboration with the National Physical Laboratory in Teddington, which not only gives access to their state of the art facilities, but also allows for collaborative work with teams that are already working in the field of low cost sensors including those working on the Breathe London project, which has recently deployed over 100 low cost sensors around Greater London.


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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/S51391X/1 30/09/2018 29/09/2023
2126120 Studentship EP/S51391X/1 30/09/2018 29/09/2022 Joseph Hayward
Description Breathe London Pilot 
Organisation National Physical Laboratory
Country United Kingdom 
Sector Academic/University 
PI Contribution I was a part of the Breathe London Pilot due to my collaboration with my the National Physical Laboratory. Part of my contribution was checking data quality and maintaining a collocation study at the National Physical Laboratory's Teddington campus. I am also continuing work on the development of an algorithm which determines the uncertainty of the measurements in the network and detects outliers and errors in the data.
Collaborator Contribution The Breathe London Pilot study involved a network of 100 AQMesh sensors deployed around London monitoring a range of air pollutants in order to increase the density of air quality measurements within London. The goal of the network was to deploy sensors in areas of high public interest such as schools. The first year of the network also utilised two vehicles fitted with high quality, reference grade air quality monitors which would drive around London and build an air quality map across the whole of London.
Impact The Breathe London Pilot has now been taken over by the new Breathe London network, using recommendations from the pilot study. The Breathe London Blueprint has now been published which can be used to guide future studies in other cities.
Start Year 2018
Title OPC-N3 Interface 
Description Python 3 Code which interfaces with an OPC-N3 manufactured by Alphasense via serial connection and properly records the data. 
Type Of Technology Webtool/Application 
Year Produced 2020 
Open Source License? Yes  
Impact The software has only just been published but is already being used in several monitoring campaigns by our research group. 
Description Poster Presentation (University of Surrey) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other audiences
Results and Impact Poster of my work was presented as part of the CArE-Cities workshop at the University of Surrey
Year(s) Of Engagement Activity 2019
Description Seminar Given at University of Sao Paulo 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Undergraduate students
Results and Impact A presentation on the work I'd done so far was given at the University of Sao Paulo and was followed by a question and answer session. The talk was well attended and can also be found online.
Year(s) Of Engagement Activity 2019