Cellphone-based air pollution detector: development from Germany
In any more or less large industrial city and its environs, air is polluted with a large amount of suspended particles. And these are, for the most part, third-party substances that industry works with, plus other man-made components, decay products formed during combustion, and everything else.
In general, all this is very unhealthy, and in some cities people even have to wear protective masks, in case of a particularly active production phase and a certain configuration of the wind rose.
Air quality assessment in such places, of course, is carried out, but by no means in all regions and not as often as we would like. The reason is the high cost of the analysis and the need to involve full-time and mobile laboratories. The other day, German scientists from the Technological Institute of Karlsruheproposed their solution .
This solution is a small module for a mobile phone that evaluates air quality using the camera and flash of the device. Of course, using the module on the phone without a camera and without a flash will not work.
The module itself is fixed to the back of the smartphone with a magnet, while the module’s holes should be located above the flash and the smartphone’s camera.
Everything works quite simply. A person presses the “take a photo” button (while setting the flash mode), the flash fires and the light from it passes through the fiber to the camera’s sensor.
The module also has a passive air intake, through which the light from the flash passes, before reaching the camera lens. The more suspended particles in a sampled air - the more light is scattered.
For their module (its body, by the way, was printed on a 3D printer), scientists have developed a corresponding application that analyzes the images received by the camera, calculating the number of particles in the air by the brightness of the pixels in the resulting image. According to experts, the brightness of the pixels in the photo allows you to fairly accurately calculate air pollution, for which a special algorithm was developed.
After testing their instrument, scientists compared their own results of studies of the state of the atmosphere with the results of studies of standard stations for determining air quality. The results converged quite accurately.
Of course, the device has limitations. In particular, it can record atmospheric pollution at a concentration of suspended particles up to about 1 milligram per cubic meter. In addition, particles less than 10 microns (and a fine dust fraction is the most dangerous, by the way), are also not yet fixed by the device.
Now scientists are engaged in improving the characteristics of the device so that it is possible to take into account the fine dust fraction.
According to the developers, their device can be useful to all people, users of mobile devices who are concerned about the quality of the atmosphere of their city. With the help of such a device and its application, it would be possible to quickly compile a map of air pollution in the city / region, after which the results would be provided to the relevant services.
The article by scientists is available in .pdf here .