Particulate MatterSection AAerosols: DefinitionTypes of Particulate Aerosols: DustsTypes of Particulate Aerosols: MistsTypes of Particulate Aerosols:SmokeTypes of Particulate Aerosols:FumesTypes of Particulate Aerosols:BioaerosolsTypes of Particulate Aerosols:FibersQuantification of AerosolsSection BBehavior of AerosolsAerodynamic Equivalent DiameterAerodynamic Equivalent DiameterAerodynamic Equivalent DiameterSection CParticle Size DistributionsParticle Size DistributionsParticle Size DistributionsSection DCytotoxic DustsCytotoxic DustsAerosols and DiseaseRegional Particle DepositionSite of Particle DepositionInspirable/Inhalable Dust DefinitionThoracic Dust DefinitionRespirable Dust DefinitionOld Particle-Size ConventionsNew Particle-Size ConventionsNew Particle-Size ConventionsSection EMechanisms of Particle Deposition in the LungMechanisms of Particle Deposition in the LungMechanisms of Particle Deposition in LungMechanisms of Particle Deposition in LungMechanisms of Particle Deposition in LungMechanisms of Particle Deposition in LungThis work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike License. Your use of this material constitutes acceptance of that license and the conditions of use of materials on this site.Copyright 2006, The Johns Hopkins University, Patrick Breysse, and Peter S. J. Lees. All rights reserved. Use of these materials permitted only in accordance with license rights granted. Materials provided “AS IS”; no representations or warranties provided. User assumes all responsibility for use, and all liability related thereto, and must independently review all materials for accuracy and efficacy. May contain materials owned by others. User is responsible for obtaining permissions for use from third parties as needed.Particulate MatterPatrick N. Breysse, PhD, CIHPeter S.J. Lees, PhD, CIHJohns Hopkins UniversitySection AIntroduction and DefinitionsAerosols: Definition Stable suspensions of solid or liquid particles in air Examples: – Cigarette smoke– Welding fume– Sea mist4Types of Particulate Aerosols: Dusts Solid aerosols generated by the handling, grinding, abrasion, or cutting of a bulk material Dust particle size is related to the amount of energy involved in creation; the higher the energy—the smaller the particle created; the lower the energy—the larger the particle created Examples: Saw dust, coal dust5Types of Particulate Aerosols: Mists Liquid aerosols generated by condensation from a gaseous state or by the breaking up of a bulk liquid into a dispersed state Droplet size related to energy input as in dusts and fibers Examples: Metal working fluid from lathe, paint spray, liquid mixing operations6Types of Particulate Aerosols:Smoke Solid aerosols resulting from the incomplete combustion of carbonaceous materials Wide range of particle sizes Size related to combustion efficiency– High efficiency = smaller particles– Low efficiency = larger particles  Examples: Wood smoke, diesel exhaust7Types of Particulate Aerosols:Fumes Solid aerosols generated by the condensation of vapors or gases from combustion or other high temperature processes Usually very small and spherical– Sources: Welding, foundry and smelting operations, hot cutting or burning operations 8Types of Particulate Aerosols:Bioaerosols Solid or liquid aerosols from biological sources May be infectious, allergenic, and/or irritating Wide range of particle sizes– Virus (0.002–0.03 um)– Tree pollen (10–100um) Examples: Mold spores, animal allergens, anthrax9Types of Particulate Aerosols:Fibers A special (based on toxicological properties) kind of dust that is fibrous in nature (i.e., longer than it is wide) Aspect ratio (L:W) defined as 3:1 or 5:1 Toxicity a function of composition, size, and number of fibers Examples: Asbestos, fiberglass, refractory ceramic fibers10Quantification of Aerosols Typical Units: mg/m3, ug/m3 Special Units: f/cm3, cfu/m3, mppcfair of volumetcontaminan of mass ionConcentrat =11Section BParticle SizeBehavior of AerosolsAirborne behavior, such as settling velocity, is a function of: Size Specific gravity Shape Surface properties Slip factorBuoyant forcesParticleGravityFluid drag forces13Aerodynamic Equivalent Diameter The Aerodynamic Equivalent Diameter (AED) of a particle is the diameter of a unit density sphere that would have the identical settling velocity as the particle Continued14Aerodynamic Equivalent Diameter Measure of behavior of particle in air Function of particle diameter, density, shape, and surface characteristics Determines site of deposition in lung Effects air sampling characteristics Referenced to spherical drop of water with identical settling velocityContinued15Aerodynamic Equivalent Diameter16Section CParticle Size DistributionsParticle Size DistributionsParticle sizes of an aerosol are typically log-normallydistributedContinued18Source: U.S. GovernmentParticle Size DistributionsLog transformation of particle size distribution is normallydistributedContinued19Source: U.S. GovernmentParticle Size DistributionsNormalized size distribution plotted as cumulativesize distributionContinued20Source: U.S. GovernmentSection DParticles and DiseaseCytotoxic Dusts Direct effect on the lungs  Examples– Silica—Silicosis– Asbestos—Asbestosis– Coal Dust—Coal workers pneumoconiosis– Beryllium—Berylliosis and chronic beryllium diseaseContinued22Cytotoxic Dusts Knowing how much and where a dust will deposit in the lungs is important for risk determination23Aerosols and Disease Disease potential is a function of:– Chemical properties of particle– Site of particle deposition in respiratory system• Head region• Thoracic region• Respiratory region– Particle clearance path/destination24Regional Particle Deposition25Site of Particle Deposition26Inspirable/Inhalable Dust Definition27Thoracic Dust Definition28Respirable Dust Definition29Old Particle-Size Conventions Non-respirable fraction (>10 µm AED)– Can be breathed into nose or mouth, penetrate head airways, and enter lung airways Respirable fraction (<10 µm AED) – Can penetrate beyond terminal bronchioles to gas exchange region30New Particle-Size Conventions Inhalable fraction (<100 µm AED)– Can be breathed into nose or mouth Thoracic fraction (<25 µm AED)– Can penetrate head airways and enter lung