Monitoring is an exercise to measure ambient air pollution levels in an area. The data will indicate the status of the quality of air we breathe. The data, over a long term, allows us to tease out patterns that help support air pollution control policy. These are portable monitoring tools that can continuously monitor a range of pollutants. The sensors are of low sensitivity and mostly suitable for identifying hotspots at roadsides and near point sources. Data can be downloaded to your computer and analysed. Air monitoring in the United States is conducted by many federal, state, local, and tribal air agencies. The U.S. Environmental Protection Agency (EPA) provides air pollution data about ozone and particulate matter (PM2.5) to CDC for the Tracking Network