AIR MONITORING

Question 1

Sampling Methods

Answer 1

Atmosphere must be sampled in a potentially contaminated work area - gasses vapors or particulatues
info is obtained by
1. area sampling - involves placing collection units in the area and leaving them for a specific period of time.
2. personal sampling with the breathing zone of the individual sometimes from the individual wearing the device.

Question 2

Sampling method selected

Answer 2

Once the sampling method has been selected then the type of sample needs to be determined.

Determinations are:

Prevailing conditions
scope of operations on site
intended use of test data
grab samples collected over 
direct reading instruments give instantaneous grab type  samples collected over brief periods of time.  Useful if you want to examine stable contaminant  concentrations or peak levels of short duration.  

instantaneous samples require - highly sensitive analytical methods due to the small sample collected

Question 3

air monitoring

Answer 3

airborne contaminants - threat to workers health HASP
identifying and mesuring those contaminants
data obtained is useful for the following:

accessing health risks
selecting PPE
determining where protection is needed
actual potential effects to the enviromnent
selecting actions to mitigate hazards safely
effectiveness of decontamination activities

Question 4

air monitoring instruments

Answer 4

sampling instrument chosen
efficiency
operational reliability
ease and use of portability
info or analysis desired
personal preference
calibration requirements

Question 5

instrument design - explosion proof

Answer 5

explosion proof
the ignition source is contained in a ridgidly built container. -
when the flamable atmosphere enters the instrument during monitoring both the arc and any small explosion are contained.
flames are cooled before they exit the container and the the explosion is contained

Question 6

Intrinsically Safe

Answer 6

reduces the potential for arcing among components by encasing the components in a solid insulating material

the instruments operational current and voltage may be reduced below the energy level necessary for the iginition of the flamable atmosphere.

An intrinsically safe device defined by electrical code NEC is not cabpale of relesasing sufficient electrical or thermal energy under normal or abnormal conditions to cause ignition of a specific hazardous atmospheere mixture in it’s most easily ignited concentration.

abnormal conditions include 
accidental damage to any wiring
failure of electrical components
application of overvoltage
adjustment and maintenance operations
etc.

Question 7

Purged

Answer 7

in a purged instrument - an inert gas buffers the arcing or flame producing device from the flammable atmosphere.

a steady stream of nitrogen or helium is passed by the potential arcing device keeping the flammable atmosphere from the ignition source.

this type of control does not satisfactorily control analytical devices that use flame or heat for analysis such as combustible gas indicator- CGI.

It also requires a source of gas that reduces instrument portability

Question 8

Certified Decvices

Answer 8

certified for use in a particular atmosphere. only approved instruments be used on site and only in atmospheres for which they have been certified.

When used to monitor unknown conditions instruments should be rated for use in the most hazardous locations.

the use of FM or UL does not guarantee certification

Question 9

Reliable and Useful Results

Answer 9

Evaluate the relaiability of the data depends on several characteristics:
response time
selectivity
sensitivity
accuracy and precision

compare its specifications
sensitivity
range
accuracy
selectivity
ability to vary amplification of detector signals
with the desired characheristics

Question 10

Response Time

Answer 10

the length of time the monitor takes whenit senses a contaminant until it generates data.

can range from a few seconds to several minutes. Short times of response are preferred.

depensds on
tests to be performed
dead time between sample periods (time analysis, data generation and data display
sensitivity of the instrument - response time impacts the pace of an overall survey and the individual tests

Question 11

Sensitivity

Answer 11

defined as the ability of an instrument to accurately measure changes in concentration. sensitive instruments can detect small changes inconentration.
measure
slight concentrations can be dangerous - sensitivity is critical

Operating range can be defines as :

uppler and lower use limints

lower - the lowest concentration that the instrument will respond to
upper - the instruments saturation concentration
operating range that will measure the ambient concentrations on site

Question 12

Amplification

Answer 12

the instruments ability to increase small electronic signalsemanating from the detector to the readout.

changing the amplification of the detector does not change its sensitivity.

amplification can be used in calibration
DC or AC powerlines
radio wave transmitters

Question 13

Selectivity

Answer 13

is the ability of the instruments to select and detect a specific chemical or group of similar chemicals.

interference from other chamicals can skew the readings and accuracy of the readings by producing a similar response.

selectivity and sensitivity must be reviewed and interpeted together

Question 14

Accuracy

Answer 14

the relationship between a true valuse the actual concentration of a contaminant

an instruments accuracy is determined by the error factor which is expressed as a percentage.

% of the true value the chemical being measue can be + / or _ of the reading

Question 15

Precision

Answer 15

a staticial measurement of an instruments ability to reproduce a reading.

an instrument does not receive routine maintenance the precision of its reading can change (become more random) can result in the amoiunt of error of the reading

instrument must give data that is correct and immediately useful and shoul dbe direct reading little or no need to interpolate, integrate or compile large amounts of data

Question 16

Combustible Atmospheres

Answer 16

several types of instruments are used to monitor hazardous atmospheres. Some uncontrolled waste sites may require the following types of monitoring as personnel characterize the site:

1. oxygen availabiliy monitory
2. combustability monitoring
3. toxic atmosphere monitoring
   
   • colormetric indicator tubes
   • specific chemical monitors
   • photo ionization detector
   • flame ionization detector
   • aerosol monitor
4. radiation monitoring

Corrosivity monitoring is omitted from this lesson since it does not pertain to air monitoring.

Question 17

Monitoring and Traning of ee’s

Answer 17

monitoring CGI for flammable gas the readout relates to the device’s gas calibration. generally methane is the gas tht calibrates CGI.

other gass than methane are detected by the CGI then the reading may be somewhat incorrect for the other gas.

significant and dangerous
if workers are not properly trained in how their specific technology works, they can be given a false sense of security when taking readings at face value.

Question 18

Catalytic Combustiion Detectors

Answer 18

are toxic atmospheric monitors that use the same detection system as CGIs and are more sensitive than CGI’s - readouts in the parts per million ppm, instead of the LEL %.
same considerationas and limitations as CGIs

Question 19

Toxic Atmosphere Monitors

Answer 19

another detection concen at an uncontrolled haardous waste relates to toxic concentrations of vapors. or gasses. The possible presence of toxic atmosphere requires that several functions be perform for safety.

identify airborne concentration that could pose toxic risk to response workes and public

evaluate the need for and type of PPE

set up work zones and areas where contaminants are not present.

several types of monitors are used for detecting toxic atmospheres.

• colormetric indicator tubes
• specific chemical monitors (hydrogen sulphide)
• phot ionization detector
• flame ionization detector
• aerosol monitor

Question 20

Toxic Atmosphere Monitors

Colormetric Indicator Tubes

Answer 20

a glass tube impregnated with a chemical. The tube is connected to a piston bellows like pump
a known volume of contaminated air is pulled at a predetermined rate through the air tube by the pump. The contaminant reacts to the chemical in the tube and
this forces a change in color. The length of the change in color is proportaionate to the contaminant concentration which is shown as ppm or as a %

Question 21

Consideration

Answer 21

detector tubs have the disadvantage poor accuracy and precision.

manufacturers report error factors up to 50% for some tubes.

advantage for detector tubes is possible for a chemical specific tube.

However, some tubes respond to interefering compounds. gasses and vapors

Question 22

Photo ionization Detector

Answer 22

PID
All atoms and molecules are composed of protons electrons which are negatively chaged particles rotate in orbit around the neucleus the dense inner portion of the atom. the neucleus consists of protons (positively charged particles ) equal in number to the electrons found in the orbital cloud.

The interaction of the oppositely chaged particles and the laws of quantum mechanics keep the electrons in orbit outside the neucleus.

Question 23

Energy

Answer 23

the energy required to remove the outer most electron from the molecule is called the ionization potential. IP and and is specific for any compound or atomic species
eV - IP measured in electron volts EV
highfrequency radiation ultra viould and above
ionizing radiation

when a photon (energy ) strikes a chemical compound it ionizes the monequle if the energy of the radiation is = to or greater than the IP on the compound. Since ions are charged particles, they may be collected on a charged plate and produce a current.

The measured current will be directly proportional to the number of ionized molecules.
The above principles are used in the design of photo ionization detector PID

Question 24

PID

Answer 24

PID contaains an UV lamp that affects the ionization of compounds to be detected. Since the ability to detect a chemical depends on the ability to ionize it , the IP of a chemical detected must be compared to the energy generated by the uv lamp of the instrument. There is a
limit to this composed by the components of air
the lamp cannot be too energetic because that would cause oxygen and nitrogen from the atmosphere to ionize and interfere with contaminant readings.

UV lamps are available in a nmber of electron volts

8. 3
9. 4
10. 5
11. 2
12. 6
13. 4
14. 7
15. 8 EV

Not all lamps are available from a single manufacturer.

To detect a particular chemical you must select the appropriate lamp for the PID.

During monitoring, the sample drawn into the instrument passes over the UV lamp where it is ionized.
If a spill of propane and vinyl chloride were to be monitored with a PID the 1st check is to see if the check is to see if they could be detected.

Question 25

IP

Answer 25

the IP of porpane is 11.1 EV and the IP of chlorida is 10 EV.
To detect both a lamp with and energy greater than 11.8 would be
If vinyl chloride were the chemical of concern then a lamp with an energy greater than 10.0 but less than 11.1 EV could be used. The propane would neither be ionized nor detected. Thus chloride woudl not interfere with the vinyl vhloride readings.

Photo ionization detectors are calibrated to a single chemical . the instruments response to chemicals other than the calibration vapors/ gas can vary

Question 26

Considerations

Answer 26

dust in the atmosphere can collect and land on the lamp and block the transmission of UV light causing a reduction in instrument reading.

this can be detected during calibration on a regular basis.

Question 27

Humidity

Answer 27

Humidity can cause 2 problems.
cold instrument is taken into a warm moist atmosphere moisture can condense on the lamp.

like dust this will reduce the available light.  moisture in the air reduces the ionization of chemicals and causes a reduction in readings.  Since an electrical field is generated in the sample chamber of the instrument radiofrequency interference from 
pulsed DC or AC power lines
transformers 
generators 
radio wave transmission
can provide an error in response.

As the lamp ages the intensity of the light decreases. It will still have the same ionization energy but th elight will decrease. The lamp will evenutally burn out. At some instances the high concentration of contamination the instrument response will decease.

Question 28

Photo ionization

Answer 28

This is considered nondestructive testing. In some cases, only .01% of the chemical is ionized. So whatever is drawn into the instrument for analysis is vented (unchanged) into the air out of the instrument into the atmosphere . Some instruments have an connection point in the exaust end of the instrument
for a gas bag or sample tube. The feature enables future analysis to be done on the atomosphere and compared with instrument readings.

Photo Ionization units include multirae, Thermo environmental instruments model 580, photo vac tip and the HNU PI 101.
photo ionization detectors are also used in gas chromotographs.

Question 29

Flame Ionization Detectors

Answer 29

FID use a hydrogen flame as a means to ionize organic vapors. FIDS measure all organic compounds containing carbon-hydrogen or carbob-carbon bonds.
The flame detector analyzes by the mechanism of breaking bonds. Inside the detector chamber the sample is exposed to an hydrogen flame that ionizes the vapors. When most organic vapors burn,
positively charged carbon containing ions are produced which are then collected by a negatively charged electrode in the chamber.

an electric field exists between the conductors sorrounding the flame and a collecting electrode. As the positive ions are collected, a current proportational to the hydrocarbon concentration is generated on the input electrode. This current is measured by a preamplifier which as an output signal proportional to the ionization current.

Question 30

Considerations

Answer 30

Flame Ionization Detectors - only respond to organic compounds. Thus, they do not detect inorganic compounds like chlorine, hydrogen cyanide, or ammonia. As with all instruments flame ionization detectors respond differentlly to different compounds.
Since most instruments are calibrated to methane all responses are calibrated to methane. Thus with survey type instruments the identity of the type of chemical must be ascertained before its concentration can be determined.

Question 31

Aerosol Monitors

Answer 31

Not all toxic materials dispersed in the air are in a form of gas or vapor. Solids and liquids can become suspended in air by combustion, by splashing liquids or by disturbing soil.

direfct reading instruments that measure aerosols (dust, mist , fumes, smoke, fog or spray) usually have a
light source or sensor that measures the amount of light scattered ny the aerosol that speads out the molecules. Readouts are in milligrams per cu meter.

Question 32

Combination Instruments

Answer 32

provide more than one detection process are available. For example trimeters tcombine an oxygen indicator, a combustible gas indicator and a toxic monitor. Meters with 4 or more functions are common with today’s technology. Detection units can have features such as alarms that signal high or low readings and also have ability for data storage.

some instruments have integrators that average concentrations over a specific period of operation. This feature allows the instrument to be used not only as a direct reading instrument but also as a long term monitor

Question 33

Alpha Beta and Gamma Radiation Monitoring

Radiation monitors and detection

Answer 33

Since the presence of ratiation cannot be detected by any of the 5 senses a survey instrument mutst be used to determine the absence or presence = amount of radiation. when radiation or radioactive situations are found on a site appropriate precautions are to be taken. to protect the personnel. 1, the Area must be corneded off, 2. appropriate agencies must be notified. 3. a health physicist must be consulted.
notified 4. no further action by waste site employees should be taken in these areas. Several types of detectors are to be used to monitor radiation. These survey meters are presented below within the context of they type of radiation taht they monitor.
the type of radiation that they monitor

Question 34

Alpha radiation monitoring

Answer 34

Even though alpha radiation is
because of the easy shielding
the probe must be held close to the alpha omitter
portable
since a layer of
workers use appropriate
unless there is an indication of alpha emitters on site

Question 35

Alpha radiation monitoring

Answer 35

Even though alpha radiation is a high energy particle it is large and therefore dissipates (uses up) its energy quickly.
because of the easy shielding
the probe must be held close to the alpha omitter
portable
since a layer of
workers use appropriate
unless there is an indication of alpha emitters on site

Question 36

Alpha radiation monitoring

Answer 36

Even though alpha radiation is a high energy particle it is large and therefore dissipates (uses up) its energy quickly. An alpha particle travels and extreemely short distance in air, actually only a few centimeters and can be shielded by a piece of paper or a layer of dry skin.
because of the easy shielding of alpha radiation an alpha monitor utilizing a detector probe with a thin plastic window must be used. Additionally the probe must be held close to the alpha emitter because of the short travel distance of the alpha particle.

There are 2 types of alpha instruments - the most commonly used are portable proportional counters and portable sincillation counters. Since a layer of dried skin or paper is sufficient in shileding for alpha particles and because of initial entry workers use appropriate respiratory protection anyway, alpha radiation is not normally monitored initially
unless there is an indication of alpha emitters on site

Question 37

Beta and Gamma monitoring

Answer 37

Beta and gamma are the most common types of radiation found at most hazard job sites. When beta radiation is present gamma radiation is also present. Therefore it is permissible to monitor with a single instrument. The instrument’s probe (or ionization chamber) has a window which is open to monitor beta/gamma radiation or closed to monitor only gamma radiation. geyger Mueller counters are an example of this type of monitor. They are used often at hazardous waste sites.

EPA recommends that a radiation monitor be used at initial site entry since radiation can only be detected by survey instruments.

Question 38

Calibration requirements for Radiation Detectors

Answer 38

Before the appropriate instrument is used it must be properly calibrated. Among its calibration requirements the NRC (Nuclear Regulatory Commission ) states that a survey instrument is properly calibrated when the instrument
readings within +/ - 10% of the calculated or known values for each point checked. Readings within +/- 20% are considered acceptable if a calibration chart or graph is attached to the instrument

Question 39

Background Radiation Check

Answer 39

When monitoring for radiation at a waste site. the instrument should be checked in a clean area. At that time the level of background radiation should be noted. normally from 10 to 20 micro R. As entry onto the site takes place the instruments should be observed for an increase of radiation above background levels.

Question 40

Radiation Action Level

Answer 40

EPA Standard Operation Safety Guidelines Action level of 1mR (miliRoentgen)
if this level is detected vacate the area deleneate and mark the perimeter of the area where the radiation has been detected and contact the health physisict for appropriate guidance

Question 41

Active samplers

Answer 41

Personal sampling. Personal monitoring means sampling the immediate surroundings of persons in their work environment. Potential contamination at such sites requires that individuals as well as the general environments be continually monitored for the presences of dangerous gasses vapors and particulates. One means of doing this is by sampling the immediate sorroundings of the persons working in a contaminated enviroment.
placing samplers devises on workers in their breathing zones helps determine and verify contamination levels previously obtained by direct reading equipment.

Question 42

Sampling systems

Answer 42

2 types of personal sampling systems

1. active samplers - mechanically move contaminated air through a collection medium.
2. passive samplers - rely on natural rather than mechanical forces to collect samples. These are classified as Diffusion or Permeation devices

rely on integrated sample collection . Integrated sample are collected when the sensitivity of a methos requires minimal sample periods or volumes or when comparison must be made to an 8 hour time weighted threshhold limit value (TLV) or an OSHA permissible exposure limit (PEL) Therefore these are typical measurements.

Question 43

Active Samplers - General Considerations

Answer 43

Active sampling systems mechanically collect samples on or into a selective medium (filtering or collection substance) . The medium is then analyzed in a laboratory to Identify or quantify collected contaminants.

Question 44

Sampling Pumps

Answer 44

rely on electrically powered pumps to mechanically produce movement.

The most reliable active sampling pumps are powered by rechargable batteries and can operate continuously at constant flow rates for 8 hours.

They are compact, portable and quiet and
can be worn by inidviduals when monitoring personal exposures.
The type of portable pump is determined by the following factors:

• physical proeprties of the contaminant
• collection medium
• collection flow rates specified by analytical
  specified by the analytical method used

Pump designs that do not interefere with worker’s motion movement and are of rugged construction are desireable.

Question 45

Calibration

Answer 45

Atmospheric must be accurately calibrated (ie adjusted) to a specific flow rate. Calibration
ensures that the meaured data can be correctly interpreted. For eg. it is important to calibrate the flow rate of the electrically powered pump.

This ensures a constant flow rate which is specified in EPA analytical methods may be achieved
personal sampling pumps are calibrated to simulate the amount of air a person can breathe
at a mimimum an active sampling should be calibrated before and after
after repair
when newly purchased
and following

Question 46

Calibration

Answer 46

Atmospheric must be accurately calibrated (ie adjusted) to a specific flow rate. Calibration
ensures that the meaured data can be correctly interpreted. For eg. it is important to calibrate the flow rate of the electrically powered pump.

This ensures a constant flow rate which is specified in EPA analytical methods may be achieved Passive sampling pumps require no calibration.

personal sampling pumps are calibrated to simulate the amount of air a person can breathe
at a minimum an active sampling should be calibrated before and after a prescribed sampling period.

Pumps should be Reclabrated
after repair
when newly purchased
and following suspected abuse

Question 47

Passive samplers

Answer 47

The key advantage of passive samplers(dosimeters) is their simplicity. These small lightweight devises
do not require a mechanical pump to move contaminant through the collection medium. Thus calibration and maintenance are reduced or eliminated but the sampling must still be accurately measures. errors can occur in the observer interpretations. Temperature and humidity can also affect accuracy but this is the case for both active and passive systems

Question 48

Radiation Dosimeters

Answer 48

measure personal dose exposures to radiation. These dosimeters are Used on sites where radioactive materials are present and careful monitoring of personnel is necessary.
there are different types of dosimeters for different types of radiation

Question 49

Thermoluminiscent Dosimeter

Answer 49

TLD badges provide a permanent record of an individuals dose equivalent of gamma / beta and xray radiation. The Albedo TLD is a neutron dose detection devise worn when working in or around an neutron radiation field. such dosimeters Must be sent to a laboratory for analysis

Question 50

Direct Reading Dosimeters

Answer 50

are pencil type devices another direct reading device t

the more chirps the stronger the field.

Question 51

Direct Reading Dosimeters

Answer 51

are pencil type devices that allow personnel to read and evaluate their exposures between TLD readings.
another direct reading device is the dosimeter is the Chirpy which is the device worn by personnel involved in the radiography work. The devise emits chirps based on the stength of the radiation field
the more chirps the stronger the field.

Question 52

The Digital Dosimeter

Answer 52

Is a battery-powered direct reading device direct reading instrument with a digital readout in mR. This device also emits chirps based on the strength of the radiation field.
Apart from the chirper, some devices are able to meet the needs of americans with disibilitese with the chest thumper because it vibrates or thumps the chest of the hearring impaired.

If a site has radioactive materials present and these types of monitors are needed
a health physicist should be present to supervise their activities.

Question 53

Personal Sampling Plan

Answer 53

it may be complex because

• it is difficult to decide what to sample
• Many workers move around on the job site and some workers require a variety of job tasks
• Efficiently keeping track of sampling data requires attention and organization