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Whether older diesel engines, tyre abrasion or swirling dirt, city centres with high traffic volumes are heavily polluted by particulate matter. Science, local authorities, residents and companies are already working on improving the quality of life in city centres. In this article, we explain how this can be achieved with sensors on drones.
Particulate matter. Causes and consequences.
Diesel exhaust fumes, abrasion processes on vehicle tyres and brakes, as well as the swirling up of dust layers, lead to high levels of particulate matter pollution, which significantly reduces air quality. Particulate matter refers to particles less than a micrometre in diameter, which are inhaled by everyone and can cause anything from respiratory irritation to illness. Heavy metals contained in brake and tyre abrasion also lead to a health risk, which is why scientists, local authorities, residents and companies are keen to identify regions that are heavily polluted by particulate matter and take appropriate measures, such as setting up low emission zones, building bypasses or improving technologies, to ensure a higher quality of life and stay in polluted regions.
Monitoring. The right way to detect particulate matter.
However, in order to be able to detect particulate matter pollution in the first place, monitoring is required. The monitoring of particulate matter is only possible with special particulate matter sensors. These sensors count particles in the air. Whether ground-based or measured in the air with drones, the functionalities of the sensors are similar. First, the air is drawn in and then counted with an optical sensor. The determined value is saved with coordinates and time in lists, which can then be analysed every second. The measurement results of permanently installed sensors can even be tracked live: https://luquas.de/luquasapp/#/map.
When counting particles, a distinction is made between the size of the particles. This is referred to as PM fractions. PM10, for example, indicates the number of particles with a diameter of 10 µm. These are mainly produced by the whirling up of dust and abrasion processes in tyres and brakes or in house fires and industrial processes. Smaller PM fractions, such as PM1 and PM2.5, are mainly attributable to vehicle exhaust gases. The Federal Highway Research Institute (BASt) states that over 100,000 tonnes of these particles are produced in Germany every year. On average, 0.1g is produced with every kilometre travelled by car.
In order to significantly reduce particulate pollution, emissions must therefore be reduced for all polluters, and the Federal Environment Agency has set corresponding targets. Special sensor technology that can detect the smallest particles is also required to detect the polluters.
Figure 1: Diagram from sample measurement
Where can I get sensors?
The University of Stuttgart, for example, supports the OK Lab Stuttgart, which aims to develop applications with the luftdaten.info project that inform and positively shape society and support administrations and authorities in making their work more transparent. This gives everyone the opportunity to build a very simple particulate matter sensor and become part of the network.
Users for whom standardised measurements and the detection of very small particles are important must use professional equipment. For example, the Fidas Fly 200 sensor developed with partner Palas is a measuring device that continuously and simultaneously measures different fractions. To be precise:
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the PM fractions PM1, PM2.5, PM4, PM10, PMtotal
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alveolar, thoracic and inhalable mass fractions according to DIN EN 481
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Particle number concentration and the particle size distribution in 32 size classes per decade in the particle size range from 180 nm to 18 µm or 400 nm to 40 µm.
Based on the certified Palas Fidas fine dust sensor, the module combines high-quality measurement technology with a data logger and live transmission. The special feature of this real-time dust monitor is its low weight and small size, which is why it can also be used with drones. The sensor can be controlled remotely and the measurement data can be displayed as live video on a monitor.
Drones make measurements in the air possible
Measuring in the vicinity of industrial plants with high chimneys has been particularly difficult in the past. However, the Fidas Fly 200 is optimised for use in the air. Attached to the HORUS 120 drone, it is ready for use in under a minute. The container system allows the Fidas Fly 200 to be attached vertically or horizontally, depending on whether the snorkel (aerosol suction tube) is to protrude forwards or upwards.
For measurements that exceed the flight time of the HORUS 120, it is also possible to use the HORUS 120 cable-connected. The HORUS-Powerline plug & play special solution is available for the HORUS container system for this purpose.
Figure 2: HORUS 120 with Fidas Fly 200 in flight