Definition

PM1 refers to particulate matter consisting of airborne solid particles and liquid droplets with an aerodynamic diameter of 1 micrometer (µm) or smaller. These particles can vary in shape, size, and chemical composition and may contain components such as organic compounds, inorganic ions, metallic compounds, and elemental carbon. Due to their very small size, PM1 particles can remain suspended in the atmosphere for extended periods and may penetrate deeply into the respiratory system when inhaled.