RADICAL is an EU-funded research project to develop a brand-new way of detecting atmospheric radicals in real-time. This will be a small, low-cost electronic sensor that will ‘sniff’ out short-lived radicals such as hydroxyl and nitrate, which play a key intermediary role in day- and night-time air quality.

This has never been done before, but if it works, our new RADICAL sensors will be cheap, small, and able to be deployed on a global scale. This will help scientists better monitor and model the role of radicals in air quality and climate change.

These sensors could also be adapted to detect other types of gases with a wide range of potential applications across manufacturing, health, and chemical industries.

Read more on our blog:  What is an electronic nose? by Professor Justin Holmes

Credit: RADICAL project

RADICAL – An electronic sensor to detect atmospheric radicals


Air pollution is a growing problem that impacts our health, the climate and the ozone layer, but we do not fully understand the underlying chemistry cycles that control air quality.

Short-lived radicals are highly-reactive species possessing an unpaired electron. In the atmosphere, they are formed as by-products from polluting emissions such as nitrogen dioxide and ozone when exposed to sunlight, and it is thought that radicals play a key regulating role in air quality cycles.

For example, radicals play a beneficial role in cleaning the lower atmosphere of air pollutants.

During the day, the hydroxyl radical (•OH) is the main driver of photochemistry in air, while at night, the nitrate radical  (•NO 3is responsible for removing gas pollutants. Both radicals play a key role in determining the levels of two important air pollutants – ozone and nitrogen dioxide – through a series of complex chemical reactions in air.

In order to fully understand the impact of radicals on air quality and climate change, we need a way of tracking them on a global scale and in real-time. 

Read more on our blog:  How atmospheric radicals transform the air by Professor John Wenger


Currently, detecting and measuring these highly reactive and short-lived radicals remains technically complex, cumbersome and expensive (see review article  Wang et al 2021).

As a result, only a few labs worldwide can perform such tests.

The aim of our project is to develop a new, low-cost way of measuring short-lived radicals in the atmosphere that can be easily implemented and deployed worldwide.

This will take the form of a state-of-the-art electronic nose that will measure the presence of airborne hydroxyl and nitrate radicals in both indoor and outdoor settings.


The World Health Organization (WHO) has described air pollution as the single biggest environmental health risk, with an  estimated 400,000 premature deaths in Europe attributable to poor air quality every year.

Short-lived atmospheric radicals are thought to play a key intermediary role in air quality cycles, and by directly monitoring the concentration of these radicals at local, regional and global scales, scientists will have a much greater ability to predict and control air quality to enable a better quality of life for citizens.

Currently, a wide variety of sensors measure air pollutants and particulate matter in cities across the globe, enabling scientists to closely monitor and predict the cycles of poor air quality.

This map shows real-time air quality readings from across Europe, as gathered by the  European Environment Agency.

The state-of-the-art technology in our RADICAL sensors could be deployed at all of the world’s air quality and meteorological stations, leading to an unprecedented level of high-quality data on the concentration of radicals at a local, regional and global level. They could also be incorporated into sensor platforms on planes, ships, balloons and drones, or even adapted to wearable health sensors for the human body.

The knowledge developed in RADICAL has the potential to bring about a dramatic breakthrough in air quality and climate monitoring, leading to health benefits for European citizens.


The RADICAL project is a collaboration between  multidisciplinary partners across Europe including University College of Cork (Ireland), HZDR (Germany), University of York (United Kingdom), National  Technical University of Athens (Greece), Smartcom (Bulgaria) and UCC Academy (Ireland).

We have extensive expertise across the fields of material science, computer modelling, nanofabrication and nanoelectronics, as well as organic, radical and atmospheric chemistry.

RADICAL  has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under grant agreement No 899282. It has a total budget of €3.2 million and will run for four years from 1 November 2020.


Follow our progress with RADICAL