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Sources and hazards of dust
Origin：Hefan Hit： Time：2020-02-27
Among the sources of dust, the dust generated by natural processes is generally the self-purification effect of the atmosphere, and the dust generated by human activities must be completed by dust removal measures. Dust and hazards from various human production activities.
I. Definition of dust
The definition of dust particles in national standards is as follows. Excerpted from "Terms and Conditions for Heating Ventilation and Air Conditioning (GB50155)," Working Exposure Limits for Hazardous Factors in the Workplace "(GBZ2) and" Ambient Air Quality Standards "(GB3095).
(1) dust (dust) produced by natural or mechanical forces, can be suspended in the air and solid particles. Internationally, solid suspended solids with a particle size of less than 75 μm are defined as dust. In the ventilation and dust removal technology, generally 1 to 200 μm or even larger particle sizes of solid suspended solids are considered as dust.
(2) aerosol (aerosol) suspended in a gaseous medium generally has a particle size range of 0.001 to 1000 m, and a peptizing state dispersion system formed by solid and liquid fine particles.
(3) Total dust is referred to as "total dust", which refers to the dust obtained by sampling with a filter film with a diameter of 40 nm according to a standard dust measurement method.
(4) Respirable dust (respirable dust). Refers to the dust particles that can be collected into the alveoli according to the standard method for respirable dust. The aerodynamic diameter is below 7.07μm, and the sampling efficiency of dust particles with aerodynamic diameter of 5m is 50%.
(5) Total suspended particulate matter (TSP) can be suspended in the air, and the aerodynamic equivalent diameter is ≤100ym.
(6) Particulate matter (particle size less than or equal to 10 μm; particulate matter, P1o) refers to particulate matter with an aerodynamic equivalent diameter of 10 μm or less in the ambient air, which is also called inhalable particulate matter.
(7) Particulate matter (particle size less than or equal to 2.5m; particulate matter, Pm2.5) refers to particulate matter with an aerodynamic equivalent diameter of 2.5 μm or less in the ambient air, and is also referred to as fine particulate matter.
(8) Airborne particles (articulate; atmospheric dust) solid or liquid particulate matter suspended in the atmosphere, also known as suspended particulate matter.
(9) Smoke (dust) A visible aerosol that is produced during high-temperature decomposition or combustion and whose particle size is generally in the range of 0.01 to 1 m.
(10) Fibrous dust) Fine filamentous dust of natural synthetic fibers.
(11) Hydrophilic dust (lyophilic dust), such as quartz pyrite and galena dust, which are easily wetted by water.
(12) Hydrophobic dust (hydrophobic dust), such as paraffin powder, carbon black, and coal powder, which are difficult to wet with water.
(13) Smoke (mist) (fume) is formed by burning or condensing the volatilized vapour of solids, and generally has a particle size in the range of 0.001 to 1 μm of solid suspended particles.
(14) Fumes) A gaseous substance with an unusual odor produced during chemical processes.
(15) Droplets) can settle under static conditions and can be suspended in gas under turbulent conditions.
(16) Mist is a small liquid quotient suspended in a gas, such as water mist, paint mist, sulfuric acid mist, etc.
(17) Particle (particulate) is a solid or liquid particulate matter, which is also referred to as particles.
(18) Haze The haze phenomenon caused by the large amount of smoke, dust and other particles suspended in the air, also known as haze.
