€6.9M EU-funded PASSEPARTOUT project to monitor air quality

29 Apr 2024

Lamp post-based gas detectors intended to prevent millions of air pollution deaths.

A new gas-sensing network that can analyze multiple gases in real-time is being developed to prevent deaths caused by ambient air pollution. This new air quality monitoring system uses laser technology to detect even the smallest amount of toxic gases in large, densely populated regions.

With multiple sensors connected to form a gas analysing network, the units can spot trace amounts of numerous gasses – including nitrogen dioxide (NO₂), sulphur dioxide (SO₂), carbon monoxide (CO), ozone (O₃), and particulate matter – in real-time.

The World Health Organisation estimates that 4.2 million people die prematurely each year from the high levels of toxic gas molecules and particulate matter they breathe in the air outdoors or ambient air pollution.

Currently, methods for assessing air quality in urban environments rely on huge units the size of refrigerators, which can cost up to €100K. Low-cost sensors rely on chemical reactions, which are inaccurate and can give false readings. However, the €6.9 million EU-funded PASSEPARTOUT aims to provide a compact detector with a complete understanding of the types and concentrations of toxic gases at a much more reasonable price.

PASSEPARTOUT project coordinator Dr William Whelan-Curtin commented, “The miniature PASSEPARTOUT hyperspectral optical-based sensors will provide a comprehensive approach to understanding urban air quality. To have a widespread network and to take meaningful steps towards a smart city, current, expensive methods are not feasible.

“At present, accurate assessments of urban air are difficult. Air quality varies significantly over time, over short distances and across different areas within a city. Traditional monitoring methods struggle to capture these nuanced variations adequately. We are working to provide a system with high precision and excellent spatial resolution to detect NO_x, SO₂, NH₃, CH₄, CO, CO₂, and black carbon,” Whelan-Curtin said.

Detectors on every lamppost

The project has aspirations to make its real-time metropolitan networks commonplace in our towns and cities. “We would like to make the technology as common as video surveillance by installing a detector on every lamppost. As part of the project, we are developing a smart phone app to check air quality in real-time. In the future, we hope this can be integrated into Google Maps so that your journey to and from work or school can show you not just traffic hotspots but also the route with the cleanest air,” he continued.

“Ultimately, we want to help save lives and help citizens everywhere enjoy clean air. At the sub-one thousand euro price tag, our technology will enable municipalities, environmental agencies, and researchers the ability to make targeted interventions and policy decisions for a fraction of the price.”

Quartz crystal technology

The system works by using the photothermal and photo-acoustic effects. The laser creates pulses or small blasts of laser light. When the laser light hits a toxic gas, the molecule absorbs light energy, giving off a heat signature that is then reported back to the system. The system then unmistakably identifies what the harmful gas is, as well as how much of it is present.

The PASSEPARTOUT system goes a step further by using quartz tuning fork technology – or Quartz Enhanced Photo-Acoustic Spectroscopy. Dr Whelan-Curtin explained: “QEPAS is particularly useful for the detection and quantification of trace gases in challenging environments. We use a quartz tuning fork with a sharp mechanical resonance to detect the signals generated by the gas sample while suppressing the background noise,” he said.

“This tuning fork detects the acoustic waves generated by the gas as it heats and cools. The signal is then analysed to determine the concentration of the target gas. The exact wavelengths of the laser, or lasers, can be tuned to match the characteristic absorption spectrum of the target gas, meaning our system categorically detects specific gases, like carbon monoxide or sulphur dioxide.”

This robust sensing allows the PASSEPARTOUT detector to monitor environments, providing dynamic and to-the-minute air quality representations continuously. “Even the most tiny fluctuations in toxic gas concentrations can be captured promptly, enabling more effective and timely interventions,” Whelan-Curtin said.

The PASSEPARTOUT team is trialling the technology in landfill sites, seaports, at the University of Bari, and in a selection of schools in Cork. The project is coordinated by Munster Technological University and will conclude in 2024. It includes 19 other partners from across Europe.