About us

The team behind this project is small but enthusiastic. Some might call it a one-person project, but that would not be fair to the friends and colleagues who contributed advice, ideas, equipment, space, and Raspberry Pi computers.

The project grew out of a hobby, some spare time, and, in a way, as an escape from everyday stress.

Project SensorBox

Project SensorBox started at the end of 2021. Motivated by frequent episodes of poor air quality in Varaždin and the lack of local official measurements for PM2.5 and PM10 particulate matter, we bought a particle sensor and connected it to a Raspberry Pi computer.

That is how it started, from the first static HTML page on a local server to a portal that now displays current data for locations across Croatia.

AirQuality.city combines data from its own SensorBox stations with publicly available data from official monitoring stations. Alongside air quality values, we also display available meteorological data such as temperature, pressure, humidity, and wind, as these help explain changes and trends.

Data are stored in a database and presented through tables, charts, and maps. The availability of historical data depends on the station and source.

Our goal

The goal of the project is to provide a clearer and more locally relevant view of air quality in Croatia.

We want to expand the SensorBox network, make better use of existing public data, and present the results in a way that is understandable and useful to the general public.

The purpose of the portal is not to frighten people or point fingers at particular sources in advance. It is to show where a problem exists, when it occurs, and how conditions change over time.

Air pollution does not matter only during individual bad episodes. Its effects also depend on the duration and frequency of exposure, which makes long-term monitoring just as important as the current reading.

Data

The portal displays two main groups of data:

• measurements from our own SensorBox stations
• publicly available data from official monitoring stations in Croatia

SensorBox stations use optical sensors for PM2.5 and PM10. Their readings are useful for local insight, trend monitoring, and identifying possible pollution episodes, especially in locations without an official station.

However, SensorBox data are not regulatory measurements and should not be used as the sole basis for official, medical, or legal conclusions.

Official decisions and final assessments should rely on data from competent institutions, professional equipment, prescribed quality-control procedures, and validated measurements.

AirQuality.city does not alter the source values from official stations, apart from processing required for display, category calculation, and combining data on the portal.

More information about sources, processing, and limitations is available on the Data Sources and Methodology page.

The SensorBox network

Official reference stations cannot cover every street, settlement, or micro-location.

A denser network of smaller sensors can help with:

• monitoring local differences
• detecting short-term changes
• identifying recurring patterns
• understanding weather and local-source effects
• monitoring areas without an official station

The SensorBox network is therefore not a replacement for the official system, but a useful addition to it.

In an ideal world, there would be no need for sensors or projects like this.

Technology

Our SensorBox stations are based on a Raspberry Pi computer, a Nova PM Sensor SDS011 particulate matter sensor, and a BME280 temperature, pressure, and humidity sensor.

Measurements are collected at short intervals. Each measurement uses a series of readings, checks the received values, and calculates an average.

The sensors are installed in enclosures that protect them from direct rain, snow, sunlight, and other external influences while maintaining the airflow required for measurement.

Like all optical particle sensors, SensorBox may be affected by high humidity, fog, station placement, nearby sources, and sensor condition. An individual reading should therefore always be viewed together with the trend, measurement time, and nearby stations.

An independent hobby project

AirQuality.city is not an official government portal and is not part of an institution responsible for regulatory air quality monitoring.

It is an independent, non-commercial project developed in spare time. The portal, equipment, and monitoring stations are funded privately, with occasional help from people who support the project.