Keywords

1 Introduction

Visualizing air pollution in the real world is not a new phenomenon, but it has largely been contained in the domain of arts, with projects aiming to make the local population aware of the pollution’s negative effects on their health. A traveling art project, giant lungs made of air filters whose color changed with time when exposed to polluted air, in multiple editions toured the most polluted cities in PolandFootnote 1 Such projects have great value, yet they have limitations as they are confined to a specific location and do not show dynamic changes in pollution rates. Still, such campaigns are a crucial step in limiting pollution in the most polluted areas, especially if pollution comes from residential sites. A decrease in emissions can be seen following informative action [4], and such initiatives often pave the way for necessary policy. Still, it is as they garner public support for such initiatives. For these reasons, we have decided to design and verify an Augmented Reality (AR) application representing current pollution levels based on location data. Seeing real-time pollution data on a personal mobile device and having it visualized in a manner that is meaningful to the device-holder at a place where they are currently has the potential to increase awareness of air pollution presence and its negative health effects.

Fig. 1.
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PM2.5 values measured every hour during one day in winter and summer 2021; a town with up to 25,000 inhabitants, data from the Environmental Protection Inspection [5]

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1.1 Household Related Air Pollution

Air quality affects the health of citizens and, unfortunately, recently has been deteriorating rapidly. However, when effects are delayed, people tend to disregard their severity, even though multiple papers closely link negative health outcomes, especially respiratory diseases, and reduced lung capacity, to air pollution [11]. The problem is particularly important in smaller towns where the important source of pollution is the heating of households and water from individual sources. One of the most dangerous pollutants is particulate matter, especially its fine fractions - PM2.5 [1, 6, 7]. Figure 1 shows how much household heating can contribute to a dangerous increase in PM2.5 levels. The chart shows the pollution levels recorded in hourly intervals in summer and winter in one of the Polish small towns (up to 25,000 inhabitants), which is dominated by single-family housing with its own heating sources. The PM2.5 level in the summer is low. In winter, however, it exceeds the norm many times in the afternoon and in the evening, when citizens usually return to their homes from work and turn on the heating.

1.2 Air Pollution Representation

The choice of the pollution representation is crucial considering the fact that the current methods of presenting information on the air quality turned out to be ineffective or gave inconclusive results (see e.g., [10]). For example, Campaña and Domínguez [3] proposed to present the different types of pollutants as enlarged models of chemical molecules. In another case, Prophet et al. [13] encouraged participants to take care of air quality in a symbolic way - by taking care of a virtual tree in an application using the data of the local pollution measurement station.

In our opinion, the choice of the correct representation of air pollution should not be arbitrary. We do the choice in a multi-stage process, which we started with a participatory workshop with potential users [8] and continued with laboratory research (see e.g., [12]). Initially, four types of visual stimuli were selected and tested: 2 positive vs. negative and 2 concrete vs. abstract. At the time when we were preparing and testing the prototype presented in this paper, the laboratory studies were still in progress, so for the purposes of the AR app tests, we chose a concrete and negative representation - enlarged PM particles.

1.3 Augmented Reality

Augmented reality (AR) is a technology that is gaining in popularity and has a chance to stay ahead of immersive virtual reality due to the availability of interesting solutions for mobile devices[9]. 3D and animated objects can be easily placed in real space thanks to toolkits such as VuforiaFootnote 2 which make developing AR applications easier for various context, varying for workplace instructions, entertainment to product design.

Vuforia is an AR add-on to one of the commercially available development engines for creating games, called Unity3d. The principle is that with the help of an application designed for a mobile device, an additional layer of abstraction can be added to the area seen by the camera. In this way, the visible area can be expanded with graphic elements, usually in the form of useful information.

For this to happen, it is necessary for the application designer to design and prepare (in appropriate formats) two types of graphic elements. The first is the so-called marker, otherwise known as a trigger - that is, an object to whose presence in the field of view of the camera the application will be “sensitive”, and the second is a target object (static image, animation, 3d model and many others) which appears in the field of view at or near the predefined marker (Fig. 2). Today, AR technology is increasingly used in industry, social media, and everyday products, among others. This is due to several basic needs that the market places on this technology, i.e.: product recognition and training, product visualisation, customer self-service, guided user manuals, and part recognition [14]. The increasing use of AR apps has been noted by several online industry journals. Insider Intelligence [15] notes the increasing share of users using augmented reality functionality, and Forbes [2] notes that this technology could be the future of social media and beyond.

Fig. 2.
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First draft of the VAPE AR app: scanning QR code to obtain the app (left), scanning the trigger to launch Vuforia AR contents (center), exploring AR contents - pollution representation overlay (right).

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2 VAPE Augmented Reality App Design

2.1 Purpose of the AR Application

The aim of the design of the application was to create an engaging experience presenting air pollution with visual cues and to communicate scientific data in a comprehensible way, by doing so, potentially raising awareness of environmental and health-related issues caused by air pollution. The application was designated to be pretested during a scientific event held in Myszków (Poland)Footnote 3, with the intention of further development in the future. The constraints affected by the out-doors-held event called for an easily accessible, compact and portable setup in addition to minimum device requirements.

2.2 Accompanying Poster

The intention of creating an informative poster complementing the experience with scientific data has affected the decision to employ a trigger-activated AR system as a base design of the application. A 100 cm per 200 cm sized roll-up banner commonly used in advertising at events was chosen as the print medium for the informative poster. The medium allowed easy and self-contained construction, a great level of portability, and re-usability, additionally to the vast canvas surface. The poster was designed and prepared for print in Adobe Photoshop (CS6), composing hand-drawn digital illustrations and text created beforehand in Procreate. The overall design of the poster was intended to be simple with key scientific information, not to overwhelm the participants of the event and to encourage engagement with the application (Fig. 3).

Fig. 3.
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Testing the prototype - the trigger (left) and a user scanning the trigger (right)

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2.3 Implementation of Air Pollution Visual Representation

The VFX representing air pollution was created in Unity’s Visual Effect Graph. The node-based Visual Effect Graph allows the creation of procedural animations of a vast number of real-time rendered particles. The particles were set to spawn evenly within a cube shaped-region of base measuring 6 m by 7 m and reaching 5 m high above the ground. The particles were spawned constantly with their basic life-span set to 10 s (not counting the added variation), and the overall capacity of particles of the VFX was set to 100000. The animation of the particles was driven by a turbulence node effecting in an appearance of the particles floating freely in the air. Each of the particles was assigned with a random texture from a set of 16 images using a flipbook particle output method. The images were edited microscopic photographs of actual air pollution particles. The assigned textures were given random sizes ranging from 0.5 cm to 2 cm. A gradient of colours from dark grey to black was assigned to the particles.

In order to raise awareness of health-related issues caused by air pollution, a visualisation of lungs has been chosen additionally to the visualisation of air pollution particles. The 3D model of lungs implemented in the application has been generated by segmentation of trachea and bronchi based on a computed tomography medical scan using 3D Slicer (4.11.20210226) software. The generated 3D model was edited and retopologiesed using Pixologic Z-Brush (4R7). The model was exported to Unity using an fbx file. The model was enhanced with a VFX animation of the same air pollution particles used in the air floating VFX. The animation shows the particles streaming through the trachea and obscuring the lungs (Fig. 4). The 3D model was visualised and augmented in front of the poster.

2.4 Application Development and Implementation

The application was compiled in Unity (2021.2.0b12) Game Engine with a Vuforia (10.0.12) plug-in installed. The Vuforia plug-in allows easy setup of AR trigger-activated system. The visualisation augmented upon the surroundings of the user was set to be triggered by targeting the smartphone’s camera on the illustration of lungs presented in the centre of the informative poster. The scene build in Unity contained a Vuforia image trigger setting, animated Visual Effects (VFX) representing air pollution particles, and a 3D model of lungs with its own VFX animation. The application was built for android devices and preinstalled on a smartphone that was later used as a visualising device during the event. The presented application was a prototype and was not available for download from the internet by the participants, yet such an option of dissemination is possible in the future.

Fig. 4.
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The animation of the particles entering via the trachea and obscuring the lungs.

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3 Pretest Results

The prototype of the AR application was presented to volunteers, participants of an open event promoting pro-ecological behavior in the city of Myszków. The event was co-organized by local authorities and non-governmental organizations. Due to the restrictions caused by the COVID-19 pandemic, all events were held outdoors with appropriate precautions. The presentation of the prototype was one of the activities that the participants of the event (mostly parents with children) could get involved in. In order to better simulate the conditions in which the application will be used in the future, it was not announced in the information inviting to the event (posters hung around the city and spots on local TV). Participants could take part in a pretest, which was organized as one of many stands (e.g., art classes with local artists, Storm Hunters information stand, non-contact sports activities, 3D printing show). Participants who decided to test the AR application were encouraged to provide feedback to the researchers operating the stand. Many participants of the event spontaneously reacted to the information posted on the poster/trigger. As intended, they tried to scan the trigger on the poster with their own phones. In such a situation, the experimenters approached potential users, explained that it was a pre-test of the prototype and, for security reasons, it was not possible to use their own devices yet, but they could see how it works on the device provided for this purpose. They then showed participants how to scan a trigger on a poster, handed over a phone with the app installed, and began observing their interactions. If test subjects watched only the poster and lungs in the AR for a long time, the experimenters encouraged them to turn around and observe the area with the layer of pollution overlaid. Most of the participants spontaneously made such an exploration. Careful observation of the lungs with pollutants entering them was rather avoided. Most users focused on watching pollution particles in the air. Below are representative testimonials from participants in the pretest:

«All this dirt makes a terrible impression. I would definitely like to have such an application to check whether, for example, I can go on a trip with my children.»

«I didn’t know that so much dust was flying in the air, especially since it’s a nice day today, you can’t smell the coal smoke»

«A man wants to do something for his health, he runs, exercises, and here you have something. If you check «on the portal», you can’t see it.»

«Maybe it would make people realize that you can’t burn just anything»

«Someone would have to want to use it. Some people don’t care.»

Thanks to positive and negative comments from users, we have the opportunity to develop the application. There is a need to conduct broader research, which would also indicate ways to popularize the application and ensure its usability, information value and impact on changing user behavior.

4 Conclusions

Visualising key data with mobile AR is a reliable way of grounding the understanding of information within the context of the environment it is displayed over. In this way, people living in a certain area may better realize the invisible presence of air pollution and how it may affect their health - but, as our subjects mentioned, only if they care to stop and check. Still, we hope that our application prototype will serve as a proof-of-concept for larger information campaigns on air pollution so that they are created in a more impactful and understandable way, relevant to their target users.