HArdware Low-cost for Air quality Detection in INdoor (and outdoor) spaces

A measuring station for monitoring air quality in work areas and beyond.

Haladin's prototype is a project carried out by CSI-Piemonte to measure air quality.
Haladin's integrates the acquired measurements from traditional networks (outdoor) and also experiences the acquisition of indoor measurements.

On the one hand it complements the traditional measurement systems using sensors with low-cost technology but good reliability and accuracy comparable, to the other responds to the need, that the market has faced only partially, to monitor air quality and the environment inside buildings (offices, schools, shopping facilities and production) with simple but effective tools, as also suggested by the World Health Organization.


The issue of air quality is central to the debate on the environment in which we move, work, live, and involves all of our behaviors,MG 8625 both general and specific aspects relevant of our lives: how we move, how we heat, what we eat, where we spend our free time, what do we use to warm up, get dressed, keep clean ourselves and our homes, how we generate the energy that allows us to use our technology, how we produce this technology, how we produce our food.
Human activities (and even some natural events, such as volcanic eruptions, the vegetable and marine evapotranspiration, winds ...) strongly influence both the composition of the air we breathe and the concentration of carbon dioxide, one of the gases responsible for greenhouse effect.
The measure of substances that determine air pollution is therefore essential to know the current situation, predict its evolution and plan for mitigation.


Air monitoring, in outdoor areas, is constantly held by the relevant authorities, primarily the Piedmont Region, which has the obligation to transpose the European Directives relating to pollution and outline the guidelines for the control and mitigation, and ARPA, which manages the monitoring networks: these are very complex and very costly management.
The indoor air monitoring scope however is currently not yet technically regulated by laws or regulations, there aren't public automated monitoring systems and measures on indoor pollutants statistically significant.


The HALADIN's project was launched precisely to complement and compensate for air quality measurements acquired from traditional networks (outdoor) or not captured at all (indoor), using low-cost technology and open-source hardware, with the following project requirements:

  • Efficiency, low costs, accuracy comparable to professional stations, easy installation and use, low consumption, immediate network connectivity and guidance to a wide circulation.
  • Hardware and software system based on the Arduino platform, which integrates low-cost sensors via a sensor board developed ad hoc.
  • Specific container for outdoor and indoor, configurable according to the needs of use, to accommodate sensors, electronic boards and communication devices with high degree of protection of the same.
  • Acquisition of the measurements taken by the sensors with programmable intervals (every second, every 5 seconds, every minute ...) and sending at regular intervals, through a Wi-Fi connection, to the Yucca platform developed by CSI on behalf of the Piemonte Region.

The application is fully part of the environment called "Internet of Things": an object becomes recognizable and "intelligent" with the ability to communicate information and access to aggregate data from other devices.


In a closed environment may occur forms of pollution harmful to human health, due to substances released by plants, furniture, paint, cleaning products, clothes, even the backpacks of students at school.
The quality of indoor environments and the presence of polluting substances inside them are in fact the subject of increasing attention. It is shown that on average we spend 90% of our time inside buildings. The right balance between acoustic comfort, thermal and visual and good air quality improves productivity in the workplace and the learning results.

The parameters measured in the indoor prototype version of HALADIN's are VOC (Volatile Organic Compounds) and Formaldehyde (CH2O): via three colored LEDs (green, yellow, red) it provides a color indication of the quality environmental: green when the ambient air is clean, yellow for warning levels and red in the case of values above the alarm levels. The levels are configurable by software.
The station also allows the detection of other microclimate physical parameters such as temperature, humidity and light.

There is of course some time the possibility to detect indoor pollutants, using more complex analysis mode and more precise, such as those developed by the mobile laboratory of ARPA Piedmont.
However the HALADIN's indoor station can be used, in an extended and permanent way, in the enclosed spaces to provide a first large screening of the quality of the places where we spend most of our time, providing, in case of alarm, the possibility to an in depth analysis, and collecting in parallel a series of data that can be the basis for a wealth of information, useful point of reference to improve the quality of the environment in which we live.

The first prototype of HALADIN's was experienced at the Public Library "Primo Levi" in Turin.


Parallel to testing indoor, based on the same design principles, it was designed and implemented an outdoor station to measure conventional pollutants: Ozone (O3), fine particulate matter (PM10), Nitrogen Dioxide (NO2), as well as temperature and humidity.

A station has been installed over the ARPA booth in Piazza Rebaudengo, Turin (a monitoring station of high-traffic area), they have also been started experimental projects to obtaining data on air quality in the provinces of Asti and the VCO.

The aim of these experiments is to evaluate the accuracy and reliability of measurements of pollutants by means of non-conventional low-cost instrumentation, to understand the feasibility of the integration of official monitoring networks (which have very high implementation costs and management) with less precise, but much cheaper, instrumentation, balancing the lower accuracy with the ability to have very dense measuring points: approach that could be an interesting integration to modeling calculations (both prognostic and diagnostic) of the spread of pollutants.

The trial of the outdoor stations will continue at other regional sites, in general near booths managed by ARPA Piemonte.

With the cooperation of CSP it was also realized a calibration chamber for sensors, equipped at the time of pickup heads for the calibrated measurement of NO2 and Formaldehyde.


The project HALADIN's is done by CSI Piemonte in close collaboration CSP ICT Innovation .

Hardware is built on official Arduino boards. It’s distributed under the Attribution-NonCommercial-ShareAlike 2.5 Generic licence. Furthermore the HALADIN’s software component has been licensed under the European Union Public Licence (EUPL).

The circuit diagrams/boards in Eagle format and software for Outdoor and Indoor prototypes are available for download below.