airborne contaminants lab

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

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

• Real 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

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

• Passive

Filters

• SKC Filter Selection Guide (good intro)

• Respirable dust and selective filtration

Calibration

• Mass of chemical determined in laboratory

)(.

)(3mvolumeS

mgMassionconcentratTWA

TLVoffraction Expected F

)(mg/mLimitExposureEL

ug)(DetectionofLimitLOD

VolumeSampleSV

3

FxEL

LODSV

Primary vs. Secondary

• Secondry– Gas meters– Rotameters

• Primary

• http://www.skcinc.com/accessories.asp

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.