Our solution! Pollution map that provides easy access to life data.

“Smarter City and Space”

This video will explain you the Smart City concept.

Pollution meter demo



To make our city a cleaner place!


Monitor the air quality of the entire city and give its residents easy access to clearly structured and always up to date information.

Mission objectives

        Our goal is to create a well engineered, weather resilient box, containing gas, temperature and pressure sensors that can easily be mounted on buildings, public transportation vehicles, bicycles etc. The data that they collect is presented on an interactive, user friendly map that shows in colour the cleaner and the more polluted areas of the city which will inform people and involve them in the issue. This serves as a milestone to our ultimate goal- to make Sofia’s air cleaner.


Map of pollution levels

The problem

The urbanisation in most of the world is creating new challenges for scientists and engineers. Pollution remains one of the most severe problems, causing a variety of health issues and affecting millions of people living in large cities.

According to the European Environment Agency, Sofia is the european capital with the most polluted air. The Bulgarian Environment Agency has an air quality monitoring system, however it is incomplete and shows data from only 13 sensors throughout the city and only displays the measurements above critical level. The awareness among citizens is low which causes negligence toward this very serious problem. We have created an ongoing online questionnaire from which the current results show that most of the people feel they are not well informed about the pollution levels in Sofia and have concerns towards the subject.

Target group

Every citizen benefits from our project, however from a business angle we have specific target groups:

  • Real estate agents, hotel managers advertising a clean residence environment
  • Joggers, athletes, bicycle riders who want to plan a clean exercise route
  • State and private institutions like hospitals and schools for which clean air environment may be crucial

Advantages of our product

  • Data on a local level that covers the entire city
  • User-friendly visualization
  • Accessible and always up-to-date information
  • Compact and easily mountable device that is well isolated from weather conditions and vibrations

Architecture of the device

Principle Scheme

Untitled Diagram4.png

The device can be thought of as a sensor hub. It’s main functions are:

Provide accurate measurements:

  • Sensors need to be calibrated at nominal conditions
  • Fault status needs to be detected depending on the sensor.
  • Detection of out of range values
  • Read status of self-diagnosing sensors
  • Compensate readings based on multiple sensors (Processed by server)
  • Communication
  • Send formated data to the server
  • Store data if no connection can be established

То оperate with low power consumption:

  • Select a MCU that runs on 3.3V
  • Decrease CPU clocks and use appropriate sleep cycles.
  • Switch sensors on selectively to conserve power.
  • Monitor battery status.
  • Use solar cell to to replenish power.

Resist the forces of nature:

  • Some sensors should not be exposed to extreme temperatures or intense direct light.
  • Some sensors need to be isolated from vibrations
  • Appropriate case
  • Rain/Snow resistant.
  • Provide exposure to the sun for the solar cell
  • Provide airflow for the sensors

Prototype Scheme

Electrical Scheme


Architecture of the application


Architecture of the application

The application is built on several layers, using JQuery, NodeJS and MySQL.  

The database layer stores the information acquired from measurements. The structure is optimized for fast searching on polluter ( CO2, Smoke etc.) and date of measurement. The following tables are present in the database schema:

  • Devices – stores information for the particular devices
  • Users – stores information for the users
  • Polluters – stores information for the different polluters
  • Measurements – stores information for particular measurements

The business layer manipulates the information so that it can be stored and later presented to the user. It is used for:

  • Removal of temperature and humidity error. This is done by approximating the error using linear interpolation of the error function for temperature and then again doing the same for humidity.
  • Conversion of the supplied sensors resistance to parts per million.
  • Providing endpoints for sending and receiving data to the server from the presentation layer and the device.

The model layer provides classes for storage of data.

The  presentation layer displays the information to the user. It uses javascript to:

  • Load an interactive map of the city using google maps API and provide interface to choose gas to display
  • Draw the grid that shows the pollution levels in the city

Team responsibilities

  • David Yordanov – Electrical engineer, hardware design
  • Kaloyan Galabov – Embedded developer, hardware design
  • Ralitsa Mancheva- Project researcher, problem analyst
  • Stoyan Naydenov – Server and data presentation implementation

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