Towards a more affordable analysis of air pollution

Satoshi Takahama and Nikunj Dudani, two scientists at EPFL’s Laboratory of Atmospheric Processes and their Impacts (LAPI), have developed an innovative system that could replace the array of instruments typically used to measure air quality by a single device small enough to fit in a carry-on bag.

The pair has just received a CHF 250,000 Innosuisse grant to support their invention’s strong market potential. They will use the proceeds to bring the technology to a viable prototype, and create a startup to deploy their device on a large scale, including in the developing world. Their project has received the encouragement of air-quality network representatives in the US and Europe (ACTRIS).

Achieving a lofty goal

Air-quality scientists currently use many different instruments to measure the composition of fine particles in the air. At the same time, many types of compounds remain elusive to several methods. With the proposed device, however, scientists will have a single instrument to automatically measure and analyze not just particulate composition but other useful properties as well, and to transmit the data effortlessly.

The scientists’ method entails projecting light onto the particles to measure their optical properties, revealing important information about their composition, origin and other characteristics. The new system offers greater portability and robustness since no bulky pumps are required. It employs infrared (IR) spectroscopy to identify the individual compounds within fine particles at a fraction of the cost of current instruments. Indeed, its low cost is comparable to that of operating air monitoring facilities, but without much of the hassle.

The prototype that the researchers plan to improve in the next months. © Alain Herzog / EPFL

IR spectroscopy is already widely used in pharmaceutical studies, food-quality analysis and the construction industry. “Because our method analyzes particulate composition online, there’s no need to store and ship filters – which can lead to measurement errors,” says Takahama, the senior scientist who is heading the project. “IR spectroscopy also allows particulate matter to be analyzed nondestructively without requiring additional sample transformation steps.” Athanasios Nenes, an EPFL professor and the head of LAPI, adds: “The new system is designed to let engineers characterize particulate composition in a non-destructive, cost-effective way. This is a lofty goal, and for the first time it is now within reach.”

Incorporated data analysis

The new system will include data analysis software in order to give customers a turnkey solution. “We wanted to standardize and automate the data analysis step, since existing instruments require a great deal of specialized know-how to be used correctly,” says Dudani, a former PhD student of Takahama. “This prevents them from being distributed on a large scale for university research or in air-quality monitoring networks.” The aim is for their compact device to be used in laboratory experiments, field measurements, governmental and non-governmental monitoring systems, manufacturing plants, and a host of other indoor and outdoor settings. It could be installed alongside building ventilation systems, for example, or purchased by manufacturers whose operations generate large amounts of fine particles.

The LAPI scientists see considerable potential for their device and are eager to implement it in concrete applications. “Air-quality engineers have been investigating uses for IR spectroscopy since the 1950s. We’re proud to finally have the right people, the right approach and the right funding to bring our idea to fruition,” says Takahama, who has been working on the concept for nearly a decade at EPFL.

The many origins of fine particles

Around 40% of Switzerland’s population is exposed to excessive levels of fine particles. Much of this particulate matter is generated by the oxidation of compounds emitted from human activities and the biosphere. In cities, particles are emitted by diesel engines, wood-burning appliances and open fireplaces. Other sources include car brakes, tires and road surfaces as they are worn down, and the dust kicked up from quarries, gravel pits and construction sites. When we breathe in these particles, the finest ones can enter deep into our lungs and induce oxidative stress throughout the body, eventually leading to cardiovascular disease, stroke and other adverse health impacts. Exposure to air pollution and fine particles are responsible for over 3,700 premature deaths in Switzerland each year, according to a 2020 report issued by the Swiss Federal Office for the Environment.