Low cost internet of things based sensor networks for air quality in cities

Rohit Chakraborty

Rohit is an Electronics and Communications Engineering graduate. His expertise is in Internet of Things (IoT) devices. These are everyday physical objects connected to the internet and able to identify themselves to other devices. IoT includes: “smart” home appliances, health trackers, environmental monitors and Transport Data Loggers (such as TDL- Bosch GmBh, Germany).

He employs a variety of deep learning techniques. These range from data analysis and machine learning, to human-computer interaction methods, such as Neural Networks and Artificial Intelligence based modelling.

The project: how to measure air pollution in cities without spending a lot of money

The World Health Organisation (WHO) estimates that air pollution was responsible for 1 in 8 of the total number of deaths worldwide in 2012. 

Rohit’s project aims to develop models and techniques that improve how we monitor and communicate air pollution levels in cities. This new approach should be achievable without the need to significantly invest in monitoring equipment. The project will explore how nitrogen dioxide relates to particulates (PM10/2.5). It will also explore how can other indicators in cities can be used to evaluate air quality. The aim is to allow people to avoid high concentrations of pollution.  

Additionally, the project explores how high-quality data (e.g. AURN – DEFRA data sets) can support the development of models and techniques. Using these data sets could considerably improve near real-time monitoring and communication of the pollution level in cities.

The model will be tested in Sheffield. We will work with local electronics company Pimoroni to develop the analytical equipment. After this we will test the low-cost IoT network in a city in a developing country (Kampala).

High quality data and the Internet of Things

Rohit working on the sensors which measure air quality
Rohit working on air quality sensors

The DEFRA high quality fixed sensors will be combined with high-quality mobile sensing vehicles from the Urban Flows Observatory.  We will also use Sentinel-5P Satellite data. This satellite data focuses on the measurement of reactive gas pollutants (such as NO2, CO, and SO2, along with PM2.5 & PM10) under prevailing meteorological conditions.

These will be used to calibrate and validate data from a network of Internet of Things based Low-Cost sensors (LCSs). Through an app on mobile phones, these sensors track NO2, CO, SO2 and fine particulate matter concentration. This will allow us to assess how the DEFRA data sets can be integrated and utilised with the LCS network when assessing gas and particulate readings in a city.

What makes the project special

The project will comprise but is not limited to i) design, development and construction of a pollution analysis instrument ii) data analysis and visualization, iii) development and validation of statistical models and algorithms for detection and estimation and short term prediction of air pollution concentration and the inference of particulate levels, iv) energy efficiency of the proposed approaches, iv) integration in a decision making system.

Unlike previous models that only encode data related to spatial locations, this project develops and validates statistical models and deep learning algorithms to capture the spatiotemporal dependency for detection, estimation and multistep short-term prediction of air pollution concentration and the inference of particulate levels.

We will also identify and incorporate other types of data provided by “social sensors”, e.g. people equipped with mobile wearable sensors such as Flow sensors from Plume labs. The project will develop methods both for people-centric and environment-centric applications. The sensor node can be on a mobile app, such as a cell phone but can also be on a vehicle platform. The research will focus on the development of the workflow to integrate DAFNI with live DEFRA and IoT sensor data novel algorithms in the context of three particular drivers.

The research will explore the development of scalable approaches for big data management. Compressed sensing methods will be adopted that allow for sampling and retaining only the most informative data.

Working with industry

Currently, Rohit is working with a Paris based company Plume Labs on use of mobile sensors. He is also working with Insplorion – a Swedish start-up – to understand how to use Nano-Plasmonic sensing to measure NOx Gases.

Rohit is involved in citizen-science based projects. For example, organising workshops to build low-cost monitors. He has also used mobile trackers on school-runs to assess how much a child is exposed to pollutants in Sheffield. The hope is that the awareness will help bring a paradigm shift in policy making and reducing pollution overall.  

Outreach and impact

A close up image of a low cost sensor, made from a drainpipe and other low cost tech
One of the low-cost sensors which Rohit has built with Clean Air Sheffield

After the publication of his study into wood burners and indoor pollution, Rohit was interview by the Guardian. This sparked a number of articles about the research and air pollution. We’ve put all the stories together here.

For an overview of Rohit’s work on air pollution, read this interview with him: Air pollution in Sheffield: interview with Rohit Chakraborty

Our Rohit is rarely out of the news! Most recently he was interviewed about air pollution post lockdown by the i newspaper. You can read the interview here.

Rohit appeared on the BBC’s One Show recently to talk about air pollution, and how it has changed due to the lockdown. He also spoke about how air pollution affects death due to Covid-19. You can find a link to the interview and a transcript here.

Read Rohit’s blog: low-cost ‘Volunteer Sensors’ to help solve the air pollution problem in Sheffield

For more updates follow Rohit on Twitter @rcrohit7


Indoor Air Pollution from Residential Stoves: Examining the Flooding of Particulate Matter into Homes during Real-World Use
by Rohit Chakraborty, James Heydon, Martin Mayfield 1OrcID and Lyudmila Mihaylova.

DOI: https://doi.org/10.3390/atmos11121326

Can portable air quality monitors protect children from air pollution on the school run? An exploratory study
James Heydon & Rohit Chakraborty
Environmental Monitoring and Assessment volume 192, Article number: 195 (2020)

DOI: https://doi.org/10.1007/s10661-020-8153-1

RoCan portable air quality monitors protect children from air pollution on the school run? An exploratory study
James Heydon & Rohit Chakraborty
Environmental Monitoring and Assessment volume 192, Article number: 195 (2020) hit Chakraborty


Professor Martin Mayfield

Department of Civil and Structural Engineering


Professor Lyudmila Mihaylova

Department of Automatic Control and Systems Engineering

Dr Nathan Adams

Department of Molecular Biology and Biotechnology