Generally, two different approaches are used to measure the amount of dust deposited on a surface; Determination of the soiling of a surface, by a change in its properties; Determination of the quantity of dust deposited, by weight. WHAT IS DUST? Dust is a generic term used to describe fine particles that are suspended in the atmosphere. Dust comes from a wide variety of sources, including soil, vegetation (pollens and fungi), sea salt, fossil fuel combustion, burning of biomass, and industrial activities. It is formed when fine particles are taken up into the atmosphere (entrained) by the action of wind or other physical disturbances or through the release of particulate-rich gaseous emissions (primary particles). In addition, gases such as sulfur dioxide and oxides of nitrogen may react in the atmosphere over time to form fine particles, such as ammonium sulfate and ammonium nitrate (secondary particles).
Dust is typically classified according to its particle size, as follows:
- Deposited matter refers to any dust that falls out of suspension in the atmosphere.
- Total suspended particles (TSP) typically refers to particles 50μm (micrometers) (0.05mm diameter) in size or less.
- PM10 refers to particles 10μm (0.01mm) in size or less.
- PM2.5 refers to particles 2.5μm (0.0025mm) in size or less.
No comments:
Post a Comment