PM2.5 refers to atmospheric particulate matter (PM) that have a diameter of less than 2.5 micrometers. Such particles are able to bypass the nose and throat and penetrate deep into the lungs and some may even enter the circulatory system.
Advances in low-cost compact sensor technologies for air quality measurement are inspiring environmental scientists and the general public to seek information about how to use them. The technology is providing more cost-effective ways to monitor air quality and helping the public learn more about air quality in their neighborhoods and communities. Air sensors are providing new ways to address air quality concerns by providing information on the kinds of pollutants in the air and their concentrations.
The EPA has an air sensor toolbox which evaluates various air pollution sensors and lists the results within a framework. These include Particulate matter (PM), ozone and other sensors.