Clean air is considered to be a basic requirement for human health and well-being. Air quality remains a major issue but, while evidence continues to accumulate as to the adverse health effects of air pollution, the main mechanisms driving these effects remain poorly understood. Ambient air pollution is composed of gases and particulate matter (PM). Atmospheric particles can be categorized according to their aerodynamic diameter: PM10 for particles equal or smaller than 10 μm, PM2.5 for those equal or smaller than 2.5 μm, and ultrafine particles (UFP) for those smaller than 100 nm. WHO guideline states that annual mean particulate matter with a diameter of less than 2.5 micrometres should not exceed 10 μg/m3. PM2.5 includes a number of harmful pollutants, and it can penetrate deep into the lungs and the cardiovascular system, posing risks to human health. WHO (2016)  estimated that 92% of the world’s population lives in places where the annual mean fine particulate matter in the air exceeds the guideline. This is also the situation in most European cities (EEA, 2019)  and therefore citizens in Europe are at risk to be exposed to potentially harmful levels of air pollutants. In recent years, 85% of exceedances of air pollutants registered by the Serbian Air Quality State Network were attributed to PM pollution. In 2017, more than 2/3 of sites that belong to national and local monitoring networks registered mean annual values of PM10 above limit (40 μg/m3) value. Data were collected with automatic monitors (thirteen stations) and using gravimetric method collecting daily samples (twelve stations) (SEPA, 2018). In addition, in 2017, SEPA reported PM2.5 levels from eight locations in the seven cities in Serbia. At one location, the PM2.5 level was above annual limit value (25 μg/m3). At all locations, PM2.5 levels were above annual guideline recommended by WHO.

Currently, information on AQ and related hazards, including PM, is mostly generic, and seldom perceived as personally relevant. For individuals to consider air pollution and its harmful effects as something personally relevant, the information needs to be personalized. For example, one could offer information about indicative level of air pollutants in microenvironment along the daily route, and explain how this is personally relevant. By using affordable personal monitors or by establishing a dense network of monitoring units, in which low-cost sensors (LCS) for various air pollutants, including PM fractions (LCS-PM) are embedded, AQ monitoring gains novel and innovative tools ready for future challenges.