A new infrared camera that detects pollutants such as sulfur dioxide – a major cause of acid rain – could help scientists identify and control such emissions before significant damage is done.

Sulfur dioxide is considered one of the most problematic contaminants, and it is particularly harmful in India, Japan and China; the latter, the greatest producer of SO₂ worldwide, has regions in which all the rain that falls is acid rain. This phenomenon occurs when the moisture in the air combines with SO₂ and nitrogen oxides to form sulfuric acid and nitric acids that fall to the Earth with every precipitation. Acidification affects lake and river water, and it hinders the development of aquatic life; it also affects vegetation, causing serious damage in forested zones. Moreover, acid rain can corrode infrastructures made of marble or limestone.

The new camera, based on technology patented by researchers from Universidad Carlos III de Madrid (UC3M) and developed by its spinoff, Sensia Solutions, detects and measures SO₂ and other pollutants (CO, NOx, SF₆, hydrocarbons, etc.) that are usually invisible to the human eye.


A new infrared camera developed by Sensia Solutions, a spinoff of Universidad Carlos III de Madrid (UC3M), can detect sulfur dioxide and other pollutants.

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“The method and the device for detecting and measuring the concentration of gases that we’ve patented makes these compounds visible due to their characteristic infrared signature,” said Miguel Ángel Rodríguez, a scientist in UC3M’s infrared laboratory. “It’s useful for identifying highly polluting vehicles that are on the road, leaks in conductions, or emissions from industrial installations, such as the chimneys of power plants.”

Although several instruments for detecting gases are on the market, none offer the advantages of this new method: the ability to determine the individualized concentration of each gas that is present in the mix, and from a distance and in real time, the researchers say. This makes it possible to detect these gases from hundreds of meters away and in a very intuitive manner, said Sensia Solutions director Francisco Cortés.

“They can be installed and easily handled by workers in all kinds of factories or industries and can even be part of a permanent monitoring system that automatically activates an alarm when it detects the leak of a specific gas, such as SO₂,” he said. The cost of these systems would be comparable to classic infrared cameras, although it may vary based on certain parameters, such as the required detection distance and the concentration of the gas, among other factors.

The device can be directly applied to numerous industries, such as metallurgy, food, energy or paper manufacturing. “Thanks to the patent rights, we are developing instruments that can remotely detect, in real time, SO₂ and other types of polluting gases, which will then allow companies and the authorities to get the sources of such emissions under control at an early stage and in an efficient manner,” Cortés said. The annual cost of air pollution in Europe reaches more than €150 billion, and the figure is about €40 billion in Spain alone, according to a recent report from the European Environment Agency. This type of pollution also causes 20,000 premature deaths every year.

In urban centers, traffic and heating systems constitute its main sources. Various studies have shown, however, that only a small proportion of the motor pool is responsible for most of the polluting emissions that are produced by automobiles. Therefore, to reduce the pollution caused by transportation, it is essential to detect and control the offending vehicles; this new generation of infrared cameras could play an important role in this task.

“The versatility of the method that we propose allows us to measure the exhaust from vehicles as they pass by on any type of road, and it can be done remotely and instantly,” Rodríguez said. “Due to the device’s extreme sensitivity, it is possible to detect even very low levels of emissions, and it can be adapted to the new legal limits that may be set for new models of automobiles in the future.”