A micro-network of low cost sensors has been built and deployed in the city of Concón with the purpose of informing the community on the air quality in their neighborhood. Currently, there are 10 active stations that measure PM10 and PM2.5, rain, temperature, humidity, wind speed and direction, and display the information in a Web page. The stations of the micro-network are installed in houses belonging to people living in the community and other public spaces. Particulate matter is measured with a Dylos monitor. Calibration of the data was performed with a Beta Attenuation Mass Monitor for PM2.5 located in the same city where the low cost monitors are deployed. PM2.5 is obtained with a linear equation that uses small and large particle counts from the Dylos monitor. Additional calibration was performed using neural networks and a noticeable improvement was obtained. The data also show that calibration made in a different city is not valid for use in Concón. As noted in many previous studies, a strong influence of relative humidity on particle count was found. The hourly profile shows that there is a strong evening peak in downtown Concón during the months of June, July and August. The peak is less pronounced at other sites, which is an indication that wood burning (or similar emissions) occur mainly in downtown Concón. On average, the Oil Refinery does not seem to increase particulate matter pollution, but short-term PM2.5 events coming from the refinery have not been analyzed yet.