Air pollution affects the quality of life (QoL) of people in large cities . Vehicular traffic, heaters and lack of clean transport alternatives are some of the causes of this problem . According to the World Health Organization, only 20% of cities worldwide comply with the required air quality standards .
Among the most dangerous pollutants, the Particulate Matter (PM) is one of the air pollutants that causes most damage to people’s health due to its characteristics of size and composition . PM10 or Coarse Particles have a diameter of less than 10 µg, PM2.5 or Fine Particles less than 2.5 µg, and PM1 less than 1 µg/m3 .
Due to the long-term exposure to air pollutants, especially PM2.5, the mortality of people with chronic diseases is increasing . Cardiovascular, respiratory and neurodegenerative diseases are directly affected by the effects of these pollutants [7, 8]. One of the ways to reduce exposure to pollution is by providing awareness about the pollution levels within the cities. Smart Cities offer data that come from the air quality stations installed in the city from which different services and applications (e.g. PulsAir application ) could gather data to empower citizens with urban, environment and health recommendations. However, the data currently available come from fixed sensor stations, and do not necessary cover the entire city.
On the other hand, there are few wearable devices available in the market that seek to provide the user with the necessary information about the pollution levels in a precise location of the city. These solutions present certain weaknesses like the Sparrow  and ATMO sensors  only focus on C02 detection, and The Plume Flow  only uses Bluetooth as a communication protocol which limits the possibility to scale-up this solution to other services within a Smart City.
This manuscript presents the design, development and initial validation of a wearable real-time Air Quality (AQ) monitoring device based on PM concentration detection, with a user-friendly interface to show AQ levels, and to report warnings, alerts and recommendations based on the pollution levels detected. The device allows to send the gathered data to other devices or services through WiFi and Bluetooth Low Energy (BLE) and can be programmed to use different communication protocols. This solution is presented as the initial step for a result applicable to large Smart Cities in order to increase the granularity of air quality information that allows the public authorities to develop the appropriate policies to improve the QoL of the citizens.
The next sections are organized as follows: Sect. 2 presents the methodology and material used to develop the proposed solution; Sect. 3 includes the design, develop and evaluation of the system; and finally, Sect. 4 presents discussions, conclusion and future steps to extend this work.