What is the Size Distribution and Sources of Particles in Ambient Air?
Particle Size and Distribution in Ambient Air The particle sizes in the ambient air are ranged from 1 nanometer to slightly more than 10 micrometers. There are three modes: coarse, fine and nano. The course mode particles are road dusts, spores and pollens. The minimum sizes of these particles are 1 to 3 micrometers. The fine mode particles are generally secondary particles formed from reactions such as smoke, sulfates, nitrates, ammonium and lead. The minimum sizes of these particles are about 0.1 micrometers. Following Steinfeld & Pandis in 1998, a typical example of the size (volume) distribution of the urban & freeway is attached below. Sources of Ambient Air Particles: EPA establishes air quality standards to protect public health, and also sets limits to protect public welfare including plants and animals, from harm, as well as protecting against decreased visibility and damage to crops, vegetation, and buildings. The followings are six common air pollutants: • nitrogen dioxide (
