A project funded by the European Union is working to develop a gas-sensing detector that analyzes several gases in real-time in cities and towns, thereby helping to prevent health issues associated with air pollution.

The researchers explained that detection system features several connected sensors that form a gas analyzing network wherein units can identify, in real time, trace amounts of different gases — such as nitrogen dioxide, sulfur dioxide, carbon monoxide, ozone and particulate matter, among others — in dynamic environments.

Current methods for analyzing air quality in these densely populated environments, the researchers explained, tend to rely on expensive, refrigerator-sized units. However, the PASSEPARTOUT project seeks to develop a compact detector capable of discerning the types and concentrations of toxic gases.

The PASSEPARTOUT hyperspectral optical-based sensors are expected to offer an approach for understanding urban air quality, which varies dramatically across time, short distances and different locations within a city.

To work, the system uses photothermal and photo-acoustic effects. As the laser light encounters a toxic gas, the molecule absorbs light energy, producing a heat ‘signature’ that is then communicated back to the system, which subsequently identifies what the toxic gas is as well as its concentration.

Additionally, the PASSEPARTOUT system also employs quartz tuning fork technology, or Quartz Enhanced Photo-Acoustic Spectroscopy (QEPAS).

The researchers 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. This tuning fork detects the acoustic waves generated by the gas as it heats and cools. The signal is then analyzed 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 sulfur dioxide.”

The technology is currently being trialed at landfill sites, seaports and schools. An accompanying smartphone app for checking air quality is also being developed simultaneously that the researchers hope will eventually be incorporated into Google Maps to show commuters the route to their destinations with the cleanest air.