airborne contaminants lab
DESCRIPTION
Airborne Contaminants Lab. Topics. Overview of workplace health and its regulation Particulates and microscopy Gases and vapors Monitoring Real time Noise. Format. Lecture with break Break Hands-on, with Sheila M Simmons Environmental Health, Safety, and Risk Management - PowerPoint PPT PresentationTRANSCRIPT
Airborne Contaminants Lab
Topics
• Overview of workplace health and its regulation
• Particulates and microscopy
• Gases and vapors– Monitoring– Real time
• Noise
Format
• Lecture with break
• Break
• Hands-on, with Sheila M Simmons
• Environmental Health, Safety, and Risk Management
• http://www.uaf.edu/safety/
Practical Application
• The terms– “Environmental Engineering” – “Environmental work
• Often extend to analyzing the workplace environment for contaminants– hence offering opinions on human health– firms often practice in this area.
Alphabet Soup
• EPA
• OSHA
• NIOSH
• AIHA
• ACGIH
Alphabet Soup
• OSHA, Occupational Safety and Health Administration
• NIOSH, National Institute of Occupational Safety and Health
• AIHA, American Industrial Hygiene Association
• ACGIH, American Conference of Governmental Industrial Hygienists.
OSHA and NIOSH
• Created in 1970’s by same act of congress• MSHA was earlier,
• OSHA– Law enforcement– Department of Labor
• NIOSH– Science– Center for Disease Control in PHS.
AIHA and ACGIH
• Industrial hygiene = science of workplace health
• AIHA accredits laboratories
• ACGIH produces TLV’s– “safe values”
Occupational Standards
• OSHA, PELs– (CFR, code of federal regulations, on line)– PELs
• ACGIH, TLVs
• NIOSH, RELs
• DFK, MAKs
TLVs
• Of the approximately 450 standards– 15% have human or otherwise well tested– 25% have some animal testing– 60% Based on “analogy,” “supposed,” or
“traditional.”
OSHA
• OSHA main site OSHA – 1910 Subpart Z– 1910.1000
• History of Tables– ANSI list– lawsuits
Contaminant Particulates
• Asbestos
• Quartz
• Dust
Asbestos is useful
• Asbestos used since ancient times• Fireproof
• WW II ship building• Insulation
• 1950’s Schools• Sound proofing,
• Many materials• Strength of fibers, chemical resistant
Asbestos kills• About 10,000 persons die each year from
asbestos related disease– 1,000 from mesothelioma– 4,000 from asbestosis– 5,000 from lung cancer
• (correlated with cigarette smoking)
• 20 to 40 year latency period• Airborne fibers, not parent material
Asbestos is regulated
• OSHA regulates workplace exposures
• EPA regulates schools
• EPA regulates disposal process
Asbestos Minerals
• Asbestos is a commercial term– Polysilicate minerals
Insert SiO4:Insert SiO4:
10 u +/-
Amphiboles• Amosite (Mg, Fe)
• Actinolite (Ca, Mg, Fe)
• Anthophyllite (Mg, Fe)
• Crocidolite (Na, Fe+++, Fe++)
• Tremolite (Ca, Mg)
Serpentine• Chrysotile (Mg)
Respiratory Tract
• Anatomy
• Physiology
• Notes on the asbestos diseases
Asbestosis
• Fibrotic lung disease
• Lungs fill with scar tissue– restrictive lung disease, stiff– oxygen transport reduced– breathing labored
Gallery
• Boston University School of Public Health
• Breath Taken: The Landscape & Biography of asbestos
• http://www/busph.bu.edu/Gallery
Normal Lung:Normal Lung:
HoneycombingHoneycombing
AsbesosisAsbesosis
Asbestos, clubbing of fingers
Asbestos, clubbing of fingers
Hairdresser, combed from hair
Hairdresser, combed from hair
Mesothelioma
• Cancer of the lining of the abdominal cavity
• Or thoracic cavity
• Fatal
childhood exposure father worked in plant and died of asbestosis note tumor on right side, fills with fluid
childhood exposure father worked in plant and died of asbestosis note tumor on right side, fills with fluid
• Mesothelioma is a rare cancer
• 2 deaths per million populations
• But in a study of asbestos insulation workers there were 175 deaths from mesothelioma.
Lung Cancer
• 32 of 41 studies indicated statistically significant increase in lung cancer of asbestos workers
• Non-smokers were 5-fold higher than non-exposed
• Smoking asbestos workers were much higher 50- to 90-fold
Toxicology, Fiber type• Some studies indicate chrysotile can
cause mesothelioma
• Most indicate amphiboles, especially crocidolite
• Some authors have concluded amphiboles are 100 times more potent than chrysotile in inducing mesothelioma.
particle
fiber
Clearance and fiber size• Residents of cities breath several hundred
grams of particles over a lifetime• Only a few grams at autopsy• Most are cleared from lung• Sorting in the airways by aerodynamic
diameter• Thin fibers penetrate much deeper than
round particles of similar diameter
Clearance mechanism by location of deposition
• Nasal clearance: – in from of ciliated, by sneezing or blowing– further back swept down and swallowed
• Tracheobronchial: cleared via cilia– mucociliary escalator
• Alveolar– macrophage
Macrophages
• Digest particles
• Carry towards ciliated airway
• Can wind up in lymph nodes and elsewhere– especially is “surface” route is overwhelmed
Robins pg. 757Robins pg. 757
Macrophage
Macrophage
Clearance
• Fibers less than 1 micron cleared half-life of 10 days
• Fibers longer than 16 micron, half-life over 100 days
• Maximum fiber length of one macrophage about 16-17 microns
Disease vs. fiber length
• Animal studies
• Dust rich in f < 5 less lung cancer
• Dust rich in f > 5 more lung cancer
• Asbestosis associated f > 2 • Lung cancer f > 5 • Mesothelioma f > 10
Dose-Response
• Measured in fibers per cc
• f/cc
• Usually states “longer than 5 u.”
• EPA uses “structures” for some purposes
• but
• Disease incidence is proportional to exposure.
Dose-Response
• 10 f/cc-yr has been suggests as threshold for asbestosis. (0.2 f/cc for 50 years)
• OSHA PELs (over 5 microns)– 12 f/cc in 1971
– 5 f/cc in 1972
– 2 f/cc in the early 1980’s
– 0.2 f/cc in 1986
– Now 0.1 f/cc.
Dose-Response, Epidemiology
• Lowest dose that produced tumors
• 16 of 19 studies lowest dose was > 10 f/cc yr
• 14 of 19 studies lowest dose was > 20 f/cc yr
• 3 studies lowest dose was < 10 f/cc yr
Dose-Response, estimated• For 1 excess lung cancer / 10,000 [ATSDR]• For environmental (24 hrs, 365 days)
– 0.35 f/cc yr (non-smokers)
• For workers (40 hrs, 50 weeks)– 1.5 f/cc yr– 0.1 f/cc for 15 yrs– 0.05 f/cc for 30 yrs
• OSHA uses 1 / 1000 for “significance,” sometimes.
ACGIH TLVs
• Amosite 0.5 f/cc, A1
• Chrysotile 2.0 f/cc, A1
• Crocidolite 0.2 f/cc, A1
• “Other forms” 2.0 f/cc, A1
• (New TLV’s do not distinguish fiber type
Toxicity, Summary
• Airborne asbestos fibers are a significant health hazard
• 0.1 f/cc (OSHA PEL) for mixed fiber types is reasonable
• Chrysotile is less toxic than amphiboles
• Fibers less than 5 microns long are less toxic than fibers over 16 microns
Microscopy
• PCM phase contrast microscopy– and more PCM– NIOSH 7400– workhorse
• Cheap, done on job
• count all fibers longer than 5 microns
– Does not distinguish asbestos from non-asbestos
PCM of Fiber Bundle
Microscopy
• TEM transmission electron microscopy– can distinguish asbestos fibers and their mineral
type– expensive (10-15 times PCM)– can count small fibers
• Beam of electrons from bottom– just like PCM
TEM of virus
SEM
• Scanning Electron Microscopy– Shines the electrons in from the top– Scans– Shows surface features.
SEM
Microscopy
• PLM polarized light microscopy– can distinguish asbestos from non-asbestos– not used for air samples– yields percentage of asbestos fibers in bulk
• Most minerals are translucent (i.e., if the mineral grain is thin enough then the light will pass through).
• Analyst examines light that passes through a given sample
• It has interacted with the internal structure of the mineral grains.
• The light emerges from the sample it has been altered due to interactions within the mineral grains.
• Each mineral is unique in its composition and/or structure so each mineral has a unique affect on light when it passes through it.
• Thus interpreting the emergent light allows a geologist to identify minerals with great accuracy.
PLM of fibers
Microscopy
• NIOSH 7400/7402– uses TEM to determine % of asbestos in PCM– standard method (“OSHA hybrid” similar)
• EPA Level II– TEM– measures small fibers (< 5 microns) as well as
larger
Summary of Microscopes
• PCM, Phase Contrast Microscope– 400 X, transparent
• PLM, Polarized Light– 400 X, mineral identification
• Binocular– 400 X, dissection and gross identification
• TEM– very powerful, expensive, identification
• SEM– vivid pictures
Quartz
Quartz
• Silicon dioxide (SiO2)• Occurs in a crystalline or noncrystalline
(amorphous) form. • Crystalline silica may be found in more
than one form (polymorphism). • The polymorphic forms of crystalline
silica are alpha quartz, beta quartz, tridymite, cristobalite, keatite, coesite, stishovite, and moganite
• Some more toxic than others
Inhalation of Quartz
• silicosis, kills 200 – 300 each year
• pulmonary tuberculosis (TB), lung cancer, and scleroderma.
• A rare multisystem disorder characterized by inflammatory, vascular, and fibrotic changes usually involving the skin, blood vessels, joints, and skeletal muscle
Silicosis
• Silicosis is similar to asbestosis and emphysema, a scarring and hardening of the lungs
• Mediated by auto-immune problems• Can kill relatively quickly in sensitive
individuals, – 2 to 5 years of exposure– sandblasters (“sand” no longer used in US.)
Monitoring Silica
• Particles size
• Crystal structure
• Use special techniques– XRD Spectrometry – IR Spectrometry – Colorimetric Spectrophotometry
Dust
• Nuisance Dust
How to collect samples
• Draw known amount of air over a filter.• Filter traps particles• Dissolve filter for PCM
– material must permit
• For silica, use cyclone to separate respirable particles
• For dust, must weight filter before and after– Use PVC filter
• More on air volume a little later.
How about gases
• Hundreds on list(s)
• What are we monitoring
• And Why?
What Chemical
• Do we know?
• Liquid
• Gas
• Particle
Chemical Properties
• Major division– Hydrophobic vs. hydrophilic
• Reactive or
• Flammable
• Explosive
• Other chemicals present
Process characteristics
• Sudden releases
• Ambient
• History
Receptor characteristics
• Most highly exposed worker
• All workers
• Area
• Work tasks– exertions– clothing
Exposure route
• Inhalation
• Dermal
• Ingestion
Air contaminant terms
• Gas– gas at NTP
• Vapor
• fume
• aerosol
• fog
• smog
Health Hazards
• Asphyxiation
• Narcosis
• Chronic toxicity
• Acutely toxic
Once you know where you are going
• Regulations may specify
• Manufactures and suppliers literature
• Industrial hygiene professional(CIH)
Two main divisions
• Air sampling– Take a sample and analyze elsewhere
• Direct reading– real time
Explosive
• Sampling or Direct?
Sampling Objective
• Documenting exposures
• Regulation compliance
• Pinpointing sources
Acute Hazard
• Alarms
Chronic hazard
• Usually health
Summary of sampling method criteria**
• Sampling Objective
• Physical and chemical characteristics of chemical
• Presence of other chemicals
• Required accuracy and precision
• Regulatory requirements
Summary of sampling method criteria, cont.**
• Portability and ease of operation
• Cost
• Reliability
• Type: area, personal, grab, integrated, etc.
• Duration of sampling and program.
Air sampling devices
• Collect and take to laboratory
SKC
• SKC
6-9”
Breathing zone
Suction pump
Flow rate control
Sampling Train
Collection device
Air inlet orifice
Airflow meter
Grab vs. Integrated
• Vacuum bottles
• Bags
• http://www.skcinc.com/prod/tsb.html
Integrated
• Absorption• Adsorption• Filters
– Cyclones– Electrostatic– Inertial– Impinger– Elutriators
Absorption
• Highly soluble and non-reactive
• Reactive
• Similar– Gas wash– spiral– fritted glass– glass beads
Gas Washing
http://www.skcinc.com/prod/impinger.html
Adsorption
• http://www.skcinc.com/abosor.html
• Passive http://www.skcinc.com/passamp.html
Filters
• http://www.skcinc.com/prod/filters.html (good intro)
• Respirable dust and selective filtration
• http://www.skcinc.com/prod/ACyclone.html
Calibration
• Mass of chemical determined in laboratory
)(.
)(3mvolumeS
mgMassionconcentratTWA
TLVoffraction Expected F
)(mg/mLimitExposureEL
ug)(DetectionofLimitLOD
VolumeSampleSV
3
FxEL
LODSV
Primary vs. Secondary
• Secondary– Gas meters– Rotameters
• http://www.skcinc.com/prod/frott.html
• Primary– http://www.skcinc.com/prod/sfflow.html
Direct Reading
• Colormetric– Length of stain– Draeger
• Tubes
– +/- 25% is an oft quoted reliability– Advantages
• cheap
• fast
Direct Reading, electronic
• Most use Wheatstone Bridge
R R
R
Variable R
M
Sensor changes conductivity
• Change with temperature– LEL/UEL
• Change with gas– O2, etc.
Calibration
• Gas supply
NFPA
• National Fire Protection Association
• Standards setting body
• Flammable Liquid
• Combustible Liquid
Flash Point
• The flash point is a Temperature.
• It is lowest temperature at which the liquid gives off enough vapor to form an ignitable mixture with the air above the mixture.
• Determined by closed-cup and a variety of test methods.
Flammable Liquid
• Flammable has flash point below 100 F (37.8 C)
Combustible Liquid
• Flash point above 100 F.
Flammable RangeAKA Explosive Range
• LEL, Lower Explosive Limit. Minimum concentration of vapors, below which propagation of flame does not take place. The mix is too lean.
• UEL, Upper Explosive Limit. Maximum concentration of vapors, above which propagation of flame does not take place. The mix is too rich.
LEL-UEL
• Typically expressed as vapor % of atmosphere.• For many liquids (or gases), the LEL is 6 to 12 %• Table in book lists some in 1% to 2% range• Contrast with TLV. Most TLVs are 100s or 1000s
PPM, while 1% is 10,000 PPM. So if vapor is less than TLV, much less than LEL.
If you don’t remember anything else
• Cannot use combustion gas meters to check if low oxygen
“Environmental” vs. Workplace
Chemical EPA(mg/m3) OSHA (mg/m3) %Carbon 10.4 58 555% monoxideStyrene 1 425 42500%
Carbon 0.7 62 8850% disulfide
MSDS• Material Safety Data Sheet• Manufactures and Suppliers of “chemicals” must
supply.• Here’s a site, Safety • Always start with MSDS
– Available – Simple– One place– Don’t rely on, dimethylmercury
Summary
• Must know what you are sampling for
• Why you are sampling
• Must calibrate
• Must keep records
• Talk to the lab.