An Evaluation An Evaluation of a Workplace Hazard: of a Workplace Hazard:

Carbon Monoxide Carbon Monoxide

Identification of Identification of Workplace HazardWorkplace Hazard

• Carbon Monoxide (CO) = a chemical Carbon Monoxide (CO) = a chemical compound consisting of one carbon and compound consisting of one carbon and one oxygen. one oxygen.

• CO is a colorless and odorless gas at room CO is a colorless and odorless gas at room temperature. Therefore, it has no temperature. Therefore, it has no WARNING properties!!!!WARNING properties!!!!

• The most likely route of exposure is The most likely route of exposure is through inhalation. through inhalation.

Extent of Hazard-OSHA Extent of Hazard-OSHA Says:Says:• ““Some 2,000 persons a year are killed out Some 2,000 persons a year are killed out

right by CO gas exposure”right by CO gas exposure”

• ““At least 10,000 more workers suffer from At least 10,000 more workers suffer from exposure to debilitating levels of CO”exposure to debilitating levels of CO”

• ““One of the most dangerous industrial One of the most dangerous industrial hazards”hazards”

• ““One of the most widespread”One of the most widespread”

Nature of HazardNature of Hazard

• Primarily known as Primarily known as an asphixiant or an asphixiant or chemical anoxiant. chemical anoxiant. This means that the This means that the CO causes absence CO causes absence or abnormally low or abnormally low amounts of oxygen amounts of oxygen in the bodyin the body

• CO simply disrupts CO simply disrupts the oxygen the oxygen transport to all transport to all tissues in the body. tissues in the body.

• CO combines with CO combines with hemoglobin in blood hemoglobin in blood to form to form carboxyhemoglobin carboxyhemoglobin (COHb)(COHb)

Nature of Hazard IINature of Hazard II• CO has an affinity for the oxygen binding site in CO has an affinity for the oxygen binding site in

the blood; 200 times more so than oxygen the blood; 200 times more so than oxygen

• Other Potential Hazards (Atypical): highly Other Potential Hazards (Atypical): highly flammable, may form explosive mixtures when flammable, may form explosive mixtures when mixed in air, may react to finely dispersed mixed in air, may react to finely dispersed metal powders to form toxic and flammable metal powders to form toxic and flammable carbonyls, may react vigorously w/ oxygen, carbonyls, may react vigorously w/ oxygen, acetylene, chlorine, fluorine, nitrous oxide.acetylene, chlorine, fluorine, nitrous oxide.

• Other Physical Properties: BP -191ºC, MP -Other Physical Properties: BP -191ºC, MP -205°C, Explosive Limits (volume % in air) 12.5-205°C, Explosive Limits (volume % in air) 12.5-74.274.2

Health Effects (Target Health Effects (Target Organs or Systems)Organs or Systems)

• BloodBlood

• Cardiovascular Cardiovascular SystemSystem

• LungsLungs

• Central Nervous Central Nervous SystemSystem

• Tissues with the Tissues with the highest oxygen highest oxygen need are first need are first affected:affected:

myocardiummyocardium

brainbrain

exercising musclesexercising muscles

Symptoms of ExposureSymptoms of Exposure

Headaches Rapidbreathing

Nausea Weakness

Dizzyness Confusion Hallutionations Cyanosis(bluishdiscoloration)

Angina (severepain)

Fainting Vomiting Fatigue

Depression ofST segment ofEKG

Diminishedmental &physical ablility

Coma Death

Particularly Susceptible Particularly Susceptible PopulationsPopulations

• ElderlyElderly

• Pregnant Women and Young Children Pregnant Women and Young Children

• SmokersSmokers

• Persons with existing illnesses: WHY???Persons with existing illnesses: WHY???

a. cardiovascular disease (heart disease, coronary artery a. cardiovascular disease (heart disease, coronary artery disease) disease)

b. pulmonary disease (asthma, emphysema, chronic b. pulmonary disease (asthma, emphysema, chronic bronchitis)bronchitis)

c. blood disorders (sickle cell anemia, lassemia, others)c. blood disorders (sickle cell anemia, lassemia, others)

Sources of COSources of CO• Incomplete combustion of anything Incomplete combustion of anything

containing carbon (fossil fuels, wood, containing carbon (fossil fuels, wood, tobacco) - Especially high in exhaust tobacco) - Especially high in exhaust from internal combustion engines. from internal combustion engines.

• CO is a metabolic product of methylene CO is a metabolic product of methylene chloride (common ingredient in paints chloride (common ingredient in paints and solvents)and solvents)

• may be be produced within the body by may be be produced within the body by catabolism (breakdown) of hemoglobincatabolism (breakdown) of hemoglobin

Typical Occupations that Typical Occupations that May Experience CO May Experience CO HazardHazard• fire fightersfire fighters

• garage mechanicsgarage mechanics

• aircraft refuelersaircraft refuelers

• truck Driverstruck Drivers

• Kiln and furnace Kiln and furnace operatorsoperators

• forklift operatorsforklift operators

• lawn care workerslawn care workers

• janitorial staffjanitorial staff

• disaster relief workersdisaster relief workers

• minersminers

• parking garage parking garage attendantsattendants

• toll collectorstoll collectors

• agricultural workersagricultural workers

Standard Methods of Standard Methods of Measurement/AssessmentMeasurement/Assessment• Direct reading CO Detector (electro-Direct reading CO Detector (electro-

chemical voltimetric sensor) - dataloger chemical voltimetric sensor) - dataloger and calibration to known gas concentration and calibration to known gas concentration requiredrequired

• sampling with calibrated vacuum pump sampling with calibrated vacuum pump through adsorption tube - laboratory through adsorption tube - laboratory analysisanalysis

• detector tubes certified by NIOSHdetector tubes certified by NIOSH

• all samples or measurements should be in all samples or measurements should be in the worker’s “breathing zone”the worker’s “breathing zone”

Other Methods (EPA Other Methods (EPA Outside Air Methods)Outside Air Methods)• Gas Filter Correlation (GFC) - relies on Gas Filter Correlation (GFC) - relies on

infrared absorbency properties of CO infrared absorbency properties of CO at 4.7at 4.7, High accuracy, greater , High accuracy, greater sensitivity, more complex equipment, sensitivity, more complex equipment, stationary measurementstationary measurement

• Nondispersive Infrared (NDIR) - CO has Nondispersive Infrared (NDIR) - CO has a characteristic spectrum that allows it a characteristic spectrum that allows it to be measured with reference to IR to be measured with reference to IR energy absorbed. Sensitive to drift, energy absorbed. Sensitive to drift, allows continuous datalogging, allows continuous datalogging, requires warm-up time, operable by requires warm-up time, operable by non-technical personnelnon-technical personnel

Applicable IH Standards Applicable IH Standards

• OSHA PEL=50 OSHA PEL=50 ppm TWAppm TWA

• NIOSH REL=35 NIOSH REL=35 ppm TWA; 200 ppm TWA; 200 ppm ceilingppm ceiling

• NIOSH NIOSH IDLH=1,200 ppmIDLH=1,200 ppm

• ACGIH TLV=25 ppm ACGIH TLV=25 ppm TWATWA

• EPA NAAQS (Primary EPA NAAQS (Primary Standard) for outside Standard) for outside air=9 ppm (TWA 8 hrs), air=9 ppm (TWA 8 hrs), =35 ppm (TWA 1 hr). =35 ppm (TWA 1 hr). This was established to This was established to protect public health protect public health (susceptible (susceptible populations)populations)

Still More TLV’s Still More TLV’s (International Flavor)(International Flavor)

• DFG MAK DFG MAK (Germany) TWA (Germany) TWA = 30 ppm = 30 ppm PEAK = 60 ppm PEAK = 60 ppm (30 min)(30 min)

• Japan (JSOH) Japan (JSOH) TWA = 50 ppmTWA = 50 ppm

• HSE OES (United HSE OES (United Kingdom) Kingdom) TWA = 50 ppm TWA = 50 ppm STEL = 300 ppmSTEL = 300 ppm

• Reference: “TLVs Reference: “TLVs and Other and Other Occupational Occupational Exposure Values” Exposure Values”

Other GuidelinesOther Guidelines• NRC (1987) EEGLs: NRC (1987) EEGLs:

10 min = 1,500 ppm 10 min = 1,500 ppm 30 min = 800 ppm 30 min = 800 ppm 60 min = 400 ppm 60 min = 400 ppm 24 hrs = 50 ppm24 hrs = 50 ppm

• NRC = National NRC = National Research CouncilResearch Council

• EEGL is Emergency EEGL is Emergency Exposure Guidance Exposure Guidance LevelsLevels

• Canadian IAQ Canadian IAQ Residential Residential Exposure Exposure Guidelines: <11 Guidelines: <11 ppm for 8 hrs, <25 ppm for 8 hrs, <25 ppm for 1hr ppm for 1hr (ASTER)(ASTER)

• WHO Concentration WHO Concentration of Concern is >30 of Concern is >30 ppmppm

CO Study, Occupation: CO Study, Occupation: Lawn Care WorkerLawn Care Worker• My project was a My project was a

simulation of lawn simulation of lawn care worker.care worker.

• 8 hour work day (~ 6 8 hour work day (~ 6 hrs of mowing)hrs of mowing)

• work equipment work equipment variedvaried

• some CO exposure some CO exposure expectedexpected

• Mowed two Mowed two properties. properties.

• One property was One property was approximately 1 approximately 1 acre and was mowed acre and was mowed with push mowerwith push mower

• 2nd property was 2nd property was about 2.5 acres and about 2.5 acres and was mowed by riding was mowed by riding mowermower

Specific Job Duties of Specific Job Duties of Worker During Study Worker During Study PeriodPeriod

• To operate gasoline powered To operate gasoline powered mowers to mow two propertiesmowers to mow two properties

• Edging not includedEdging not included

• To obtain gas for mower if emptyTo obtain gas for mower if empty

Subject of Study:Subject of Study:

• Question: Will CO Exposure exceed any Question: Will CO Exposure exceed any standards or guidelines during a standards or guidelines during a simulated average 8-hour work shift for simulated average 8-hour work shift for an Lawn Care Worker?an Lawn Care Worker?

• There seems to be few published reports There seems to be few published reports on this type of a study. Some reports on this type of a study. Some reports focus on small gasoline engines used focus on small gasoline engines used inside buildings where the CO is easily inside buildings where the CO is easily concentrated.concentrated.

Equipment in UseEquipment in Use

• Push mower Push mower

• riding lawn tractor riding lawn tractor

• automobile (to move between sites)automobile (to move between sites)

IH Equipment Used for IH Equipment Used for Hazard AssessmentHazard Assessment

• Metrosonics PIM 1100 Industrial Hygiene Metrosonics PIM 1100 Industrial Hygiene Personal Monitor - Courtesy of Personal Monitor - Courtesy of Metrosonics, Inc.Metrosonics, Inc.CO Electrochemical Oxidation SensorCO Electrochemical Oxidation Sensorwith a Heat Stress Monitor (core with a Heat Stress Monitor (core temperature and heart beats per temperature and heart beats per minute)minute)with Noise monitor (slow, A-weight)with Noise monitor (slow, A-weight)

FindingsFindings

• Minimum Minimum 0 ppm 0 ppm

• Average Average 5 ppm 5 ppm

• Maximum Maximum 150 ppm 150 ppm

• 15 min STEL 15 min STEL 13 ppm13 ppm

• TWATWA 5 ppm 5 ppm

Comparison to Exposure Comparison to Exposure Guidelines and StandardsGuidelines and Standards

• The OSHA PEL TWA was not exceeded.The OSHA PEL TWA was not exceeded.

• The NIOSH REL TWA was not exceeded.The NIOSH REL TWA was not exceeded.

• The NIOSH Ceiling was not exceeded.The NIOSH Ceiling was not exceeded.

• The ACGIH TLV was not exceeded.The ACGIH TLV was not exceeded.

• None of the other suggested guidelines were None of the other suggested guidelines were exceeded.exceeded.

Comments on DataComments on Data

• The momentary CO The momentary CO level measured level measured during the start-up during the start-up of the riding mower of the riding mower was elevated, was elevated, however the however the duration of the duration of the exposure was short.exposure was short.

• Graph of Data Graph of Data (available as (available as handout)handout)

• Breaks and Lunch Breaks and Lunch are distinct on are distinct on data graphdata graph

Possible CO Hazard Possible CO Hazard Control Measures (if Control Measures (if needed)needed)• Eliminate - ex. Substitute gas mower with Eliminate - ex. Substitute gas mower with

electric or manual mower.electric or manual mower.

• Control Source - ex. Adjust equipment to Control Source - ex. Adjust equipment to control emissions (catalytic converters) or control emissions (catalytic converters) or improve efficiency of combustion processimprove efficiency of combustion process

• Apply appropriate ventilation or exhaust Apply appropriate ventilation or exhaust mechanism (only inside enclosures), mechanism (only inside enclosures), ensure proper operation of exhaustsensure proper operation of exhausts

More CO Hazard Control More CO Hazard Control MeasuresMeasures

• Provide appropriate personal Provide appropriate personal protective equipment (PPE) to protective equipment (PPE) to workers, when sources can not be workers, when sources can not be controlled or eliminated and levels controlled or eliminated and levels are suspected as hazardous. SCBA are suspected as hazardous. SCBA (NIOSH specified) is often specified. (NIOSH specified) is often specified. Definitely applies to fire/rescue Definitely applies to fire/rescue personnel.personnel.

Summary of Key PointsSummary of Key Points

• Carbon Monoxide Carbon Monoxide exposure is a exposure is a serious health serious health and safety hazard.and safety hazard.

• CO is especially a CO is especially a hazard in enclosed hazard in enclosed spaces spaces

• CO did not seem to be CO did not seem to be a serious hazard a serious hazard during normal mowing during normal mowing operations.operations.

• If CO levels were high If CO levels were high and exceeded and exceeded applicable TLVs, applicable TLVs, Control measures Control measures could be effectively could be effectively instituted.instituted.

Conclusion: No CO Conclusion: No CO Standards or Guidelines Standards or Guidelines ExceededExceeded• If this simulation was representative of If this simulation was representative of

a normal workday of a lawn care a normal workday of a lawn care worker, then it appears that CO does worker, then it appears that CO does not pose a serious threat to normal not pose a serious threat to normal healthy adults. healthy adults.

• It is conceivable that that these low It is conceivable that that these low level exposures may cause measurable level exposures may cause measurable effects in susceptible individuals. More effects in susceptible individuals. More data is needed.data is needed.

Note: Other Potential Note: Other Potential Hazards Associated w/ Hazards Associated w/ Featured OccupationFeatured Occupation• Heat StressHeat Stress

• Noise/VibrationNoise/Vibration

• Injuries (overturned Injuries (overturned tractors, cuts, eye tractors, cuts, eye injuries, thrown injuries, thrown debris)debris)

• fire (burns)fire (burns)

• UV radiation UV radiation exposureexposure

• exposure to exposure to bioaerosols (mold bioaerosols (mold spores, pollen) - a spores, pollen) - a problem for problem for asthmatics and asthmatics and allergy sufferersallergy sufferers

Note: CO can be a Hazard Note: CO can be a Hazard in Nonoccupational in Nonoccupational SettingsSettings

• SchoolsSchools

• Homes Homes

• CommutingCommuting

• HospitalsHospitals

• Nursing HomesNursing Homes

Electronic ResourcesElectronic Resources

• Internet: Internet: – www.osha.gov/www.osha.gov/

– www.cdc.gov/niosh/homepage.htmlwww.cdc.gov/niosh/homepage.html

– www.epa.gov/iaq/www.epa.gov/iaq/

– www.safety-fl.org/www.safety-fl.org/

– www.acgih.org/www.acgih.org/

AcknowledgementsAcknowledgements

• Thanks goes to:Thanks goes to:– Jennifer, Ed Williams Jennifer, Ed Williams

and Mary Gestaldi and Mary Gestaldi for use of their for use of their property (land and property (land and work equipment)work equipment)

– James Slattery from James Slattery from Metrosonics, Inc. for Metrosonics, Inc. for use of IH equipmentuse of IH equipment