AIR SAMPLING AT WORKPLACES: SAMPLING STRATEGY, EQUIPMENT AND FACTORS AFFECTING THE QUALITY OF SAMPLES.

AIR SAMPLING AT WORKPLACES: SAMPLING STRATEGY, EQUIPMENT AND FACTORS AFFECTING

THE QUALITY OF SAMPLES

PRESENTATION PLAN

•CHAPTER 1: WHY TO SAMPLE THE AIR?CHAPTER 2: HOW TO SAMPLE THE AIR?

SAMPLING STRATEGYBASIC STEPS OF SAMPLING STRATEGYREMARKS

CHAPTER 3: HOW LONG TO SAMPLE?CHAPTER 4: SAMPLING TECHNIQUES AND FACTORS AFFECTING THE SAMPLE QUALITY

WHY TO SAMPLE THE AIR?TO KNOW:• WHICH SUBSTANCE IS THE WORKER EXPOSED?• HOW MUCH SUBSTANCE IS THE WORKER

EXPOSED?• WHEN DOES THE EXPOSURE HAPPEN?

FORMS THE BASIS FOR PREVENTION MEASURES

HOW TO SMAPLE?

SAMPLING STRATEGY• WHAT TO SAMPLE?• WHEN TO SAMPLE?• HOW OFTEN TO SAMPLE?

HOW TO SAMPLE?

BASIC STEPS OF SAMPLING STRATEGY • DETERMINATION OF FACTORS AT THE

WORK PLACE• ESTIMATION OF LEVELS OF EXPOSURE

– How much a substance used or formed?– How frequent the subsatance is used or formed?– How long the workers use it or make it form?

HOW TO SAMPLE?

BASIC STEPS OF SAMPLING STRATEGY

• MAKE A LIST OF POSSİBLE EXPOSURES

• PUT THE MOST POSSIBLLE AND/OR MOST DANGEROUS EXPOSURES FIRST IN THE LIST

HOW TO SAMPLE?

BASIC STEPS OF SAMPLING STRATEGYMORE POINTS TO CONSIDER WHILE

FORMING THE LIST (PROPOSED BY EN689)– THE DUTIES IN THE WORK– WORK FORMAT AND TECHNIQUES– PRODUCTION PROCESSES– PHYSICAL CONDITIONS OF THE WORK PLACE– SAFETY PRECAUTIONS AND OPERATIONS

HOW TO SAMPLE?

BASIC STEPS OF SAMPLING STRATEGYMORE POINTS TO CONSIDER WHILE

FORMING THE LIST (PROPOSED BY EN689)– AIR CONDITIONING AND OTHER ENGINEERING

CONTROLS– EMISSION SOURCES– EXPOSURE DURATIONS– WORKLOAD

HOW TO SAMPLE?

REMARK 1• PERSONAL SAMPLING: NUMBER OF

SAMPLES– DETERMINE GROUPS ACCORDING TO

EXPOSURE TYPES.(EX.: WELDERS, PAINTERS, TRANSPORT VEHILCE DRIVERS ETC.)

– CONSIDER THE HOMOGENITY OF GROUPS WITHIN THEIRSELVES

– IF HOMOGEN GROUPS: 1 SAMPLE FROM EVERY 10 WORKERS

– IF NON-HOMOGEN: INCREASE THE NUMBER OF SAMPLES

HOW TO SAMPLE?

REMARK 2

• STATIONARY SAMPLING:– USE IT IF

a)A WORKING ROOM IS VISITED OCCASIONALY (BATTERY CHARGE ROOM)

b)A LOT OF WORKERS ENTER OR LEAVE THE WORKING ROOM IN WHICH A HIGH RANKED SUBSTANCE IN YOUR LIST EXSITS IN THE AIR (MANUAL LOADING OR DISLOADING OF A TRUCK)

HOW TO SAMPLE?

REMARK 3

• DO THE SAMPLING AS MUCH AS– TECHNICAL MEANS– COST– TIME

ALLOWS

STARTING FROM THE BEGINING OF YOUR LIST

HOW LONG TO SAMPLE?

• THE TECHNICAL MEANS DICTAES THE DURATION OF A SINGLE AIR SAMPLE SUCH AS:– CAPACITY OF FILTERS OR SORBENT TUBES– CAPACITY OF PUMPS– THE LIMITATIONS GIVEN IN THE STANDARD

METHODS USED

BUT!!!!

HOW LONG TO SAMPLE?EN 689 STATES THAT:

Sampling Time Number of Min. Samples For Each Shift

• 10 seconds 30• 1 minute 20• 5 minutes 12• 15 minutes 4• 30 minutes 3• 1 hour 2• ≥ 2 hours 1IN ORDER TO REPRESENT AN 8 HOUR SHIFT

HOW LONG TO SAMPLE?

ci: Occupational exposure concentartion (mg/m3 or ppm or etc.)

ti: :Exposure time fo i’th job (hours)

∑ti:Sfift duration (Generally 8 hours)

IF THE WORKER DOES SEVERAL JOBS OR HAS LARGE INTERVALS BECAUSE OF ABSENCE OF TASK

THEN: CALCULATE:

SAMPLING TECHNIQUES AND FACTORS AFFECTING THE QUALITY

OF SAMPLES

A

AFTER

QUESTIONS

TIME

EVENTS

QUESTIONS

PRESENTATION

VOLATILE ORGANIC GASES VOLATILE ORGANIC GASES

•SAMPLING TECHNIQUES: ACTIVE CARBON SORBENT TUBES AND LOW FLOW SAMPLING PUMPS

FACTORS AFFECTING THE QUALITY OF FACTORS AFFECTING THE QUALITY OF VOC SAMPLESVOC SAMPLES

•SELECTION OF LOCATION OR PERSON:

GAS CONCENTRATION VARIATIONS ARE ESTIMATED USING TWO NUMBERS

•Reynolds Number

•Archimedes number

R eD h U

Arg D h T w T s

T mU2

FACTORS AFFECTING THE FACTORS AFFECTING THE QUALITY OF VOC SAMPLESQUALITY OF VOC SAMPLES

•As the Reynold's number incraese•More homogenious distribution•Lower exposure at the source

•As the Archimede's number increase,•Movements towards the hot walls•Lower average concentartions

FACTORS AFFECTING THE FACTORS AFFECTING THE QUALITY OF VOC SAMPLESQUALITY OF VOC SAMPLES

•Temperature: Affects the adsorbtion desorbtion equilibrium in the sorbent tube•This equilibrium can be formulazized with Langmuir isotherm

bP1 bP

b T k a k d

FACTORS AFFECTING THE FACTORS AFFECTING THE QUALITY OF VOC SAMPLESQUALITY OF VOC SAMPLES

•As the temperature incraeses: Equilibrium shifts towards desorbtion side•b(T) value decreases

So the capacity of the sorbent tube decraeses

Beware of High Temperatures (See your method)

bP1 bP

b T k a k d

FACTORS AFFECTING THE FACTORS AFFECTING THE QUALITY OF VOC SAMPLESQUALITY OF VOC SAMPLES

•The pressure of the air passing through the sorbent tube drops.•WHY?: ERGÜN Equation

PL

150v 0D p

2

1 2

3

74

v 02

D p

13

FACTORS AFFECTING THE FACTORS AFFECTING THE QUALITY OF VOC SAMPLESQUALITY OF VOC SAMPLES

•As the pressure drops: Adsorbtion gets difficult•High flow rates cause higher pressure drops

Beware of high flow rates (Use low flow

rates allowed in your method)

Formaldehyde Samples

•Passive sampler filled with DNFH is used

Formaldehit Numunelerinin Kalitesini Etkileyen Faktörler

•Same factors with VOCS in terms of distribution and adsorbtion•BUT! More sensitive to Reynold's and Archimede's numbers•WHY?:DIFFUSION EQUATION

tD 2 r , t

FACTORS AFFECTING THE QUALITY OF FORMALDEHYDE SAMPLES

•BUT!: More sensitive to temperature

•WHY?: Its adsorbtion is more exothermic.

DUSTSTHERE ARE TWO MAJOR TYPES WHE SAMPLING IS CONSIDERED

•Cyrstaline structure dusts

•Fibrous dusts

Cyristalline Structure Dusts

High flow rate pumps are used for sampling these dusts

Sidekick Deluxe

INHALABLE AND RESPIRABLE DUSTS

•Cyclone head for respirable dusts

•IOM head for inhalable dusts.

Cyclone head IOM head

FACTORS AFFECTING THE QUALITY OF CYRSTALLINE DUST SAMPLES

•Reynold's number (more or less sensitive depending on the type of dust)

•Less sensitive to Archimede's number.

WHY: Larger particles than gases which are hardly affected by bıuancy forces of air.

FACTORS AFFECTING THE QUALITY OF CYRSTALLINE DUST SAMPLES

•Filling of filter pores during samples: The velocity of air passing through the filter falls down • WHY→Pressure drop equation on filters

P 60

dN r pd r p

Vr p

C r p

1Ad r p

CHECK THE FLOW RATE AFTER SAMPLING (AVERAGE VALUE IS USED IN SOME METHODS)

FACTORS AFFECTING THE QUALITY OF CYRSTALLINE DUST SAMPLES

•CONDITIONING:Some methods propose conditioning in order to control the humidity effects.

•IF YOUR MEHTOD PROPOSES:• The preconditioning and post-

conditioning must be done at the same conditions

FACTORS AFFECTING THE QUALITY OF CYRSTALLINE DUST SAMPLES

•Post-conditioning should be done with the casette: the air circulation in the laboratory oven

FACTORS AFFECTING THE QUALITY OF FIBROUS DUST SAMPLES

•Same factors with cyrstalline dusts•Special Sampling heads are used•Special preperation of filters before sampling

Fibrous dust head