Measuring vehicle emissions to analyse air quality: the Air Quality Platform

Air quality is an issue for countless people, particularly those living in urban areas, and climate change is an issue for everyone. In the fight against the pollutants behind these issues, information is essential.

In collaboration with ESA and AWS, Darwin has been working on the Air Quality Unit, a device that measures the pollutants emitted by vehicles, and the Air Quality Platform, an online platform that gathers and processes this information. We spoke to Darwin’s CEO, Milos Petrovic, about how this air quality analysis works and why it matters.

What is the Air Quality Unit?

The Air Quality Unit is a collection of sensors and electronics inside a 3D-printed plastic case. These sensors can measure temperature, humidity and light levels, as well as the levels of pollutants such as carbon dioxide, carbon monoxide, ammonia and nitric oxide in the air.


The Air Quality Unit can be attached to a vehicle or drone to take measurements of the air as it travels. It’s lightweight and simple to secure using suction. It transmits information about air quality to the Air Quality Platform, where it can be viewed and analysed.

We currently have a working prototype that can collect air quality data on the go. In fact, we’ve already made use of it; we brought it to Cornwall in July and equipped it to the van testing our ubiquitous communications technology.

From the Cornwall trial, we identified some changes we’d like to make; for example, we’d like to experiment with different materials for the casing and streamline the design. Once we’ve made these changes, we’re planning to use the Air Quality Unit in our future autonomous shuttle trials.

What is the Air Quality Platform?

The ESA Air Quality Platform was originally created by ESA for educational purposes. ESA has provided schools across Europe with the tools they need to set up air monitoring stations, and the resulting air quality information is displayed in real time on an interactive map.

Although the Air Quality Platform was created as an educational tool, Darwin took an interest in it, as it was sophisticated enough to aid in Darwin’s goal of helping commercial organisations track their emissions. We spoke to a senior ESA engineer about the possibilities of the platform, and ESA agreed to build an Air Quality Platform for Darwin’s use.

Darwin supplied material to ESA, and ESA provided the hardware, casing and software. Once we had received the ‘off-the-shelf’ platform from ESA, we started working with ESA to modify it to our needs: adding new sensors, for example.

Darwin’s modified version of the Air Quality Platform is currently hosted by AWS, rather than by ESA, although the unit also transmits information to ESA’s servers. For more information about Darwin and AWS, take a look at our article on the experience of working with AWS.

With the Air Quality Platform, we can analyse information from the Air Quality Unit and draw conclusions. For example, the Air Quality Platform can map air quality levels in a particular area, or give an idea of the level of pollution produced by the vehicles reporting air quality information. By presenting this information in an understandable way, the Air Quality Platform makes it possible to identify areas where improvements can be made.

How does the Air Quality Unit work?

The Air Quality Unit takes and analyses measures of the air. The many sensors inside the unit work in various ways.

For example, some of them are chemical sensors. A miniature plate may be heated to a high temperature: 200°C, for example. When ammonia (NH3) particles make contact with the heated plate, they break down into ammonia’s constituent elements: nitrogen and hydrogen. This creates a tiny electrical impulse, and the sensor counts these impulses to get an idea of the number of ammonia particles in the air.

Some of the sensors, meanwhile, work on mechanical principles, such as the particle sensors.

The unit is able to measure the number of particles of a certain size: particles of up to 10 microns, and particles of up to 2.5 microns. The smaller 2.5 micron particles are generally more dangerous because they’re too small to be filtered out by hairs inside the nose, so they can end up in the lungs and bloodstream more easily.

To measure particles based on size, the Air Quality Unit uses a miniature chamber. A filter ensures that only particles below a certain size can enter the chamber, in which a tiny laser beam, projected from one wall, illuminates a plate on the other side. When a particle passes through, the particle casts a shadow on the plate. The sensor can count the number of these moving shadows detected in a given time period and, with that information, the Air Quality Platform can estimate how many of these particles are in the air.

Electronics inside the Air Quantity Unit constantly receive information from the sensors and send it wirelessly to AWS, where it can be analysed on the Air Quality Platform. Darwin’s work combining terrestrial and satellite communications is useful here, as the Air Quality Unit needs to maintain a steady connection to AWS as it moves around.

Why is measuring air quality important?

Darwin’s goal is to make it possible to fit this air quality monitoring technology on the factory line, or to retrofit it into existing vehicles.

If many vehicles were equipped with air quality monitoring technology, they would be able to create an image of what air quality is like across the country, and of how different vehicles can impact on it.

With this information, governments could take action to improve air quality in the areas where improvement is most needed. For example:

  • Creating low emission zones, or zero emission zones, in areas with dangerous levels of air pollution.
  • Planting trees to absorb pollutants such as carbon dioxide.
  • Providing more charging points and other incentives to use electric cars, rather than petrol or diesel cars, in areas with high emissions. (For more about the potential for electric cars to reduce emissions, take a look at our article on self-driving cars and the environment.)

Organisations could also use this information in various ways. For example:

  • Environmental agencies could create maps of pollutants – carbon dioxide, carbon monoxide or dust particles, for example – and see how they change over time.
  • Delivery or transport companies could make informed decisions about the greenest vehicles available to them.
  • If a vehicle’s tyres are producing a lot of airborne particles as they wear down, the manufacturer could look at other models of tyre, or at technology designed to capture these particles.

It’s important not to feel helpless in the face of large environmental issues like air pollution. It’s absolutely possible to make changes and improvements, and the Air Quality Platform is a step towards that.

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