The particle matter concentrations in the subway stations should be monitored and controlled for the health of commuters on the subway system. Seoul Metro and Seoul Metropolitan Rapid Transit Corporation are measuring several air pollutants regularly. In this paper, the reliability of the cheap instruments using light scattering method is improved with the help of a linear regression analysis technique to measure the $PM_{10}$ concentrations continuously in the subway stations. In addition, a monitoring system is implemented to display and record the data of $PM_{10}$, $CO_2$, humidity, and temperature. To transmit and receive these measured sensor data, CDMA M2M wireless communication method is applied.