Air pollution: monitoring and improvement

Tracking an invisible killer

27 June 2018

Air pollution is the largest single environmental threat to health in the world. Tom Hall looks at its impact on our lives and new ways to monitor and improve air quality

Unlike the thick noxious smog of old, today’s air pollution is an invisible but deadly cocktail of nitrogen dioxide, particulates and ozone, among other substances. The effects on people range from heart attack, stroke and the development of cancer to cognitive impairment and genetic changes in utero, predisposing babies to health problems later in life.

Globally, air pollution costs up to £5tr a year, affecting 92% of the population and associated with more than 3m deaths per annum, as the World Health Organization (WHO) Global Urban Ambient Air Pollution Database (update 2016) indicates. In the EU, 40m people in the 115 largest cities breathe air exceeding WHO air-quality guideline values for at least 1 pollutant, according to its regional office for Europe. WHO also estimates that the economic cost of air pollution in the UK is £54bn annually, with more than 40,000 related deaths per year – about 25 times greater than the number from road traffic accidents. The UK government also expects dirty air to reduce the life expectancy of everyone in the country by 6 months on average.

Saving lives

Reducing air pollution could therefore save millions of lives and trillions of dollars. Public anger at the failure of local governments to address air-quality in a timely and efficient manner has also substantially increased. Awareness has grown since the highly publicised Volkswagen emissions scandal, while campaigning legal organisation ClientEarth has also raised the issue through a succession of High Court challenges of the UK and other governments over their failure to address illegal air-pollution levels. While clean-air guidelines and limits have been in place for decades, cities still fail to meet any legal targets; London, for example, hit the annual recommended limit for air pollution within the first month of 2018. Land use and planning is beginning to see the impact of this increased concern for air quality. Local authorities are taking action through section 106 agreements, or section 75 agreements in Scotland, which legally require funding for air-quality monitoring equipment as part of planning conditions. There is also increasing demand from local authorities for developers to model the impacts of their projects on air quality, while new roads are now being subjected to impact assessments using new sensors and modelling techniques. In this context, EarthSense was established in 2016 as a joint venture between aerial mapping company Bluesky International and the University of Leicester to commercialise air-quality innovations resulting from research.


EarthSense aims to provide products and services that enable the visualisation and resolution of air-quality issues. We measure and demonstrate trends in urban air pollution to enable policy-makers, planners and others to develop strategies to reduce it, using a mixture of sensors, advanced modelling techniques and data.

Reducing air pollution could save millions of lives and trillions of dollars

Our involvement with a BBC television documentary Fighting for Air, shot in Kings Heath, Birmingham, showed that air pollution could be reduced by up to 20% with coordinated action, thanks to measurements taken with our Zephyr sensor. This led to more than 1.5m views of our MappAir air-quality data.

Increasingly, those responsible for policy development are looking to enhance their capability in measuring air pollution on a hyperlocal scale to inform policy development and the use of equipment such as chemiluminescent monitoring stations. While highly accurate, such stations are so expensive that only 1 or 2 are generally deployed per city – Leicester for example has two for a population of around 300,000 – and there are only around 150 operational nationally most of the time. Zephyr by contrast is a small, calibrated air-quality sensor that can measure nitrogen oxide, nitrogen dioxide, ozone, particulates PM1, PM2.5 and PM10, temperature and humidity. It costs on average a few thousand pounds, compared to tens of thousands for a monitoring station, and can be fitted to a lamp post or used in a vehicle or a backpack, for example. It provides data in real time, so pollution events or hot spots can be identified immediately.

National data

Our sensors also feed into our national data product MappAir, where each square of data is roughly twice the size of an average football pitch. Combining data from satellites and our air-quality monitoring sensors together with open-source data, we have used complex modelling techniques to create this highly accurate map. It shows how air pollution, specifically nitrogen dioxide, changes across the UK and within towns and cities, highlighting likely sources and potential clean-air refuge areas. Since March, the map has also included particulates PM2.5.

We are releasing a high-resolution data product for hourly alerting and forecasting up to 3 days ahead. As the Zephyr can feed directly into MappAir, we can also provide a subscription service where we install and maintain the sensor and provide access to local measurements as well as MappAir. Accurate map-based data such as that provided by MappAir is designed for a wide range of applications, including local planning, enforcement and mitigation strategies, as well as commercial applications such as conveyancing and health diagnostics. It is hoped the MappAir products will also help with public engagement and behavioural change initiatives.

Development impacts

EarthSense can help developers with their planning applications by accurately monitoring the impact of any demolition or modelling the effect of a new development on an area. It can also advise on the most effective mitigation measures such as the location of green screens or vegetation. Without modelling, such interventions can exacerbate the issue by trapping pollution rather than dispersing or deflecting it.

Selling property

There is increasing evidence that more homebuyers are concerned about air-quality issues, which have been seen to affect the sale price by 15% in some areas. In response, the environmental report company Future Climate Info will be the first to incorporate our air-quality data sets into its conveyancing reports.

We have also undertaken a range of air-quality monitoring projects, from placing monitoring equipment on a rocket to mounting mobile mapping with air-quality sensors on hybrid cars and trucks, which enable automatic electric switching in clean air zones or areas with high pollution. We can even model the air inside vehicles or buildings to assess how pollution enters enclosed spaces.

Our long-term ambition is to measure a wide range of gases, particulates and other environmental hazards such as noise, and to model them across the world.

Tom Hall is Managing Director of EarthSense

Further information