Councils are required to monitor and track concentrations of particulate matter against national guidelines and standards and address any identified issues. The particle measured to determine the quality of air is PM10, a mixture of gases, liquids and particles than are smaller than 10 micrometres, or one-fifth of the diameter of a human hair. A winter monitoring programme of PM10 was carried out in twelve towns around the region over a three year period from 2001 to 2003. This identified the towns of Taihape and Taumarunui as having the worst air quality in the region and as potential areas where air quality could breach the national air quality standards during winter months. As a result we now monitor these continuously with results displayed in the map below.