Inhalation Monitoring Data Collection Guidelines 

July 1, 2002 

Developed by the US. Environmental Protection Agency~ Office of Pollution Prevention and Toxics 

(OPPT)/Economics, Exposure, and Technology Division (EETD)/Chemical Engineering Branch (CEB) 

INTRODUCTION 

At times, inhalation monitoring or sampling data may be requested to help OPPT to better evaluate the 

health risk to employees for substances covered under the Toxic Substances Control Act (TSCA). 

To help ensure that the appropriate data is received to allow OPPT to conduct its review and to 

minimize the need for additional efforts on the part of the submitter, CEB has prepared the following 

guidance on developing an inhalation monitoring study protocol prior to conducting monitoring. If 

monitoring has already been completed, improvements or additions may need to be made to the final 

report so that OPPT can evaluate it in the proper context. Incomplete protocols and/or results may not 

be adequate for OPPT to fully evaluate exposures or exposure potential, and may require additional 

work on the part of the submitter. Although a comprehensive exposure assessment is not needed or 

required by OPPT, keep in mind that all monitoring studies should ideally fit within the structure of a 

larger exposure assessment plan and a complete industrial hygiene program. 

This document is intended to provide general guidance to environmental, safety, and health 

professionals in conducting monitoring studies to assess inhalation exposure concerns. It does not 

cover all individual situations or special circumstances. Monitoring studies should be undertaken by a 

qualified individual who has been trained in the evaluation and control of workplace exposures. 

Use the following outline and questions to assist in the development of the inhalation monitoring study 

protocol: 

A. Objective of the Monitoring Study: 

Clearly describe the objective of the monitoring study. 

• What are the final data results sought through this study? 

• What are the exposures of concern? 

• What is the target population of workers? 

• Is the study designed to assess acute or chronic exposures? This will affect the pattern and 

duration of sampling, and also possibly the media used to collect the samples. 

• Is the objective to determine average or worst-case exposures to the substance? 

If the data are from a previous study, the purpose of the original data collection or study may have 

been different than the current objective. 

• Was personal monitoring conducted in a way that will give an accurate picture regarding 

exposure to the substance of concern, particularly if the original purpose of the monitoring 

study was different? 

• If the purpose of monitoring was different, such as prompted by a specific, unrelated incident, 

was the monitoring method one which will accurately characterize the exposures currently 
under evaluation? For example, are long-term exposures (months or years), shift-long 

exposures, or short-term exposure (15 minutes or less) of the greatest interest in evaluating 

exposures? 

• Although not necessary for OPPT purposes, it may be useful to consider how the objective of 

this monitoring study fits logically into a larger exposure assessment framework for the 

workplace. As noted in the introduction, any individual sampling plan or objective should be 

part of a larger exposure assessment strategy for the entire workplace. This exposure 

assessment should include identifying all workplace hazards, developing similar employee 

exposure groups, conducting baseline exposure monitoring and/or modeling studies where 

necessary to characterize the hazards, using follow-up monitoring and/or modeling as needed to 

confirm compliance with relevant exposure thresholds, and evaluating exposures using both the 

results and professional judgement. 

B. Sampling Strategy/Sampling Methods: 

Describe the sampling plan and methodology. 

• Is the sampling method one that has been validated by an independent organization (i.e, the 

National Institute of Occupational Safety and Health (NIOSH), the Occupational Safety and 

Health Administration (OSHA), the American Society for Testing and Materials (ASTM), 

etc.)? 

• What sampling media or direct reading instrument will be used? What is the strategy that will 

be used for sample collection, including sample location, flow rates, sampling time, and sample 

replication? 

• Will enough samples be taken to ensure that the results are statistically significant for the 

population of concern? · 

• Will a worst-probable or a random sampling strategy be employed? 

Guidance on Developing a Sampling Strategy 

A number of strategies and methodologies have been developed to determine the appropriate 

number of samples that are necessary to estimate exposure profiles for specific tasks. Although 

models have been developed to assist with this task, professional judgement is important in 

determining the appropriate number of samples to be taken. Before considering the number of 

samples needed, identify and categorize the major types of processes to be evaluated and the 

different types of job tasks associated with each of these processes. Worker groupings by 

specific job tasks are commonly referred to as similar exposure groups (SEGs).1 Once the 

major processes, job tasks, and similar exposure groups have been outlined, specific sampling 

can be planned. 

Four sample groups or types should be identified and considered for the sampling strategy: 

1. Identify the group of employees at the greatest risk of exposure from each of the 

exposure groups or job tasks to be evaluated and collect samples from this group to 

assess likely maximum exposures. 

2. Identify locations in which to conduct process sampling (sometimes referred to as 

sampling) to map possible worker exposures in and around relevant process equ: 

This may help to identify one or more SEGs where maximum exposures are li' 
occur. 

3. Randomly select workers for personal monitoring in the defmed SEGs in order to 

determine typical or average exposures in these groups (please see section below, "The 

Importance of Random Sampling", for more information on random sample selection). 

4. Where relevant, be sure to identify and select workers in non-routine (i.e., maintenance 

activities) for personal monitoring to determine likely worst-case and typical exposures 

for these activities. 

Note: Sometimes it is not possible to determine a maximum risk exposure group. If this is the 

case, random sampling techniques should be used for sample selection in all similar exposure 

groups and for process sampling. 

Determining the Number of Samples to Collect 

It is important to determine the appropriate number of samples needed ·to get statistically 

significant results from a sampling study. The number of samples needed will depend on a 

number of different factors, including the objective of the monitoring study, the characteristics 

of the SEG (e.g. degree of homogeneity), and the actual measured levels of exposure relative to 

an occupational exposure limit (OEL) or threshold of concern. 

A Strategy for Assessing and Managing Occupational Exposures, published in 1998 by the 

American Industrial Hygiene Association (AIHA), recommends that samples should be 

collected up to a statistical point of diminishing returns for each sample type or similar 

exposure group. According to this strategy, statistics show that there will be a point at which 

additional samples will not significantly improve confidence in the overall results. Assuming a 

normal population distribution and using at-table, the maximum value derived from taking 

additional samples is reached after about 6 to 10 measurements within a defined SEG. 

Typically, at least six measurements should be taken for each SEG to ensure with sufficient 

confidence that exposures for the SEG have been adequately characterized. (If initial 

measurements demonstrate that exposures are far less than 10% of the threshold of concern or 

higher than the actual threshold of concern, fewer measurements may be needed) .. For 

exposures very near the threshold of concern or OEL, more than six measurements will likely 

be needed to determine that exposures are, in fact, consistently below the threshold of concern 

(up to 10 or more measurements). Professional judgement should be used to make this 

determination, taking into account factors such as the cost of additional sampling relative to the 

cost of controls to limit exposures, and the level of statistical confidence in the results that is 

desired or needed.2 The chart below shows the increased confidence achieved by increasing 

the number of samples taken: 

Effect of Sample Size on Estimating Population Mean and Standard Deviation3 
so 

c 

I 

"0 

At 

- 1) 

D 

E 

! 

·10 

-o 5 tO 

Numw of Samples 

--------.-~U~ppe:rcoolldenca lirm 

z : 11 1 : .i i i ; ; ,,.cemral o:s'!iitaiB 

"lower cooftdei'IO!t lln11 

2 8 10 12 16 

Number of Sample.• 
If A Minimum Level of 90% Confidence in Sampling Results is Desired 

If it is desired or necessary to obtain at least 90% confidence that maximum exposures are 

accurately characterized by the sampling results for a particular SEG, regardless of exposure 

monitoring or control costs, the following table can be used to estimate the minimum number 

of samples that will be necessary to achieve this level of statistical certainty 0 This table is 

published by NIOSH in their Occupational Exposure Sampling Strategy Manual, Chapter 3 

(1977)0 If the number of workers in a SEG is known, the table provides the number of samples 

required to ensure with 90% confidence that at least one individual among those with the 

highest 10% of exposures for that SEG is contained in the sample set. As indicated above, 

however, additional samples over 10 within a single exposure group may not provide a great 

deal of additional confidence in the results and may result in siginificant additional sampling 

costs and time to complete the sampling study 0 Professional judgement should be used to 

determine cases where more than 10 samples are necessary to evaluate exposureso4 

Size of Partial Sample for Top 10% Exposure at a Confidence Level o£0.905 

Size of group Number of Required 

N Samples 

8 7 

9 8 

10 9 

11-12 10 

13-14 11 

15-17 12 

18-20 13 

21-24 14 

25-29 15 

30-37 16 

38-49 17 

50 18 

The Importance of Random Sampling 

If it was not possible to detem1ine an individual employee or group of employees with 
maximum risk for exposure, random sample selection techniques should be employed. Often, 

this can be difficult given real-world constraints, but in general, the use of certain sample 

selection techniques will improve the likelihood that the samples collected accurately 

characterize the exposure variability within an SEG. 

To conduct random sampling, sampling incidents should be chosen at random first by date, 

then by shift, and then by worker. During random sampling, samples should not be conducted 

in clusters (i.e., such as over a one-week period), but over a longer period of time. This period 

oftime should be long enough to adequately capture exposure variability, but not so long that it 

affects the completion of the sampling study within a reasonable period of time. Multiple dates 

for sampling should be selected with no consideration for any particular conditions or events 

that could affect worker exposures. After multiple sampling dates are chosen, multiple work 

shifts, where applicable, and multiple workers must also be sampled to fully characterize 

exposure variability and reduce bias in the results. 

Random sampling may be especially difficult for non-routine operations such as maintenance 

work. However, creative approaches can sometimes be used to conduct random sampling for 

these types of tasks. Examples include using a shorter sample time, or using a combination of 

full-shift sampling along with measurements from direct reading instruments.6 

C. Laboratory Analysis/Analytical Method: 

Describe where the laboratory analysis was conducted and what analytical chemistry method was used. 

• Has the analytical method used been validated by a third party (e.g., was a specific NIOSH, 

OSHA, or ASTM method used)? 

• Is the laboratory accredited by a relevant industrial hygiene organization, such as the AIHA? 

• What types of analytical methods are used by the laboratory to ensure accuracy and precision 

(e.g., how many analyses are conducted of the same extract of a collected sample)? 

• If applicable, what type of specific direct reading instrument(s) were used for monitoring, and 

why? What is the level of detection, accuracy, and precision that can be obtained from this 

type of instrument? 

D. Quality Assurance: 

Discuss the number of samples collected, how many shifts and workers were sampled, how these shifts 

and workers were selected for inclusion, how the samples were stored after collection, and how they 

were transported to the laboratory for analysis. 

• Were steps taken for quality assurance purposes (i.e., were blank samples or spiked samples 

sent to the laboratory along with the field samples collected)? 

• Were the recommended sample storage and transport procedures followed prior to analysis? 

• If used, were direct reading instruments properly calibrated? What error rate can be expected 

from the instrument measurements? 

• How was the number of samples that were taken determined? 

• If applicable, were individual workers and shifts randomly selected for sampling using 

appropriate methods? 

• Were the samples properly collected to assess intended exposures (i.e., average or worst-case 

exposures)? 

E. Sampling Results and Discussion: 
Provide a summary of the results of the monitoring study. Include units, sampling time intervals, and 

limits of detection where applicable. Provide any necessary context or evaluation of the results. 

• Describe any equations or calculations used to evaluate the results, including exposure 

assessment calculations, statistical calculations, or mathematical exposure modeling done using 

the data collected. 

• Characterize the results in terms of the population targeted in the monitoring study (i.e., 

individual SEGs, etc.). 

• Discuss the uncertainties in the results. 

• Compare the results to previous monitoring studies. 

F. Description of Industrial Hygiene Program: 

Briefly describe the industrial hygiene program at the facility where the monitoring study was 

conducted. 

• Is a written industrial hygiene program in place? What are the basic elements of the program? 

• What types of controls (i.e., ventilation, work practices, respirators) are in place to prevent 

inhalation exposure, as well as other types of exposure? 

• What types of employee training are conducted to inform workers of the hazards related to their 

jobs? 

• What types of evaluation methods are used to assess the effectiveness of the program? How 

frequently is monitoring conducted? How often is the program evaluated? 

If you have any questions regarding this guidance, please contact the OPPTIEETD/CEB engineer 

responsible for your case or Jennifer Sahmel, CEB Industrial Hygienist, at (202) 564-8524 or 

sahmel. j ennifer@epa. gov. 
References 

Hewett, Paul. Past Chair, Exposure Assessment Strategies Committee, American Industria! Hygiene 

Association. Unpublished/Verbal communication: General Guidance on Developing an Exposure 

Assessment Strategy. April2002. 

Mulhausen, John R. and Damiano, Joseph. A Strategy for Assessing and Managing Occupational 

Exposures, Second Edition. Fairfax, VA: American Industrial Hygiene Association Press, 1998. 

National Institute of Occupational Safety and Health. Occupational Exposure Sampling Strategy 

Manual, Chapter 3: Exposure Measurement Sampling Strategy. pp. 34-35. DHHS (NIOSH) 

Publication No. 77-173, January 1977. http://www.cdc.gov/niosh/77-173.html 

Plog, Barbara, ed. Fundamentals oflndustrial Hygiene. Third Edition: Chapter 17, Methods of 

Evaluation, pp. 397-416. National Safety Council, 1988. · 

U.S. Environmental Protection Agency, Technical Document for Characterizing and Presenting 

Summary Chemical Exposure Assessment Results (working draft), presented at the Voluntary Children' 

s Chemical Evaluation Program Workshop, December 11-13,2001. 

http://www .epa. gov I chemrtk/ etechdoc. pdf. 

1 Mulhausen, John R. and Damiano, Joseph. A Strategy for Assessing and Managing 

Occupational Exposures, 2nd edition. American Industrial Hygiene Association (AIHA Press): 1998, 

pp. 41-56. 

2Mulhausen, John R. and Damiano, Joseph. A Strategy for Assessing and Managing 

Occupational Exposures, 2nd edition. American Industrial Hygiene Association (AIHA Press): 1998, 

pp. 89 -112. 

3Mulhausen, John R. and Damiano, Joseph. A Strategy for Assessing and Managing 

Occupational Exposures, 2llil edition. American Industrial Hygiene Association (AIHA Press): 1998, 

pp. 107. 

4Nationallnstitute of Occupational Safety and Health. Occupational Exposure Sampling 

Strategy Manual, Chapter 3: Exposure Measurement Sampling Strategy. pp. 34-35. DHHS (NIOSH) 

Publication No. 77-173, January 1977. http://www.cdc.gov/niosh/77-173.html 

5National Institute of Occupational" Safety and Health. Occupational Exposure Sampling 

Strategy Manual, Chapter 3: Exposure Measurement Sampling Strategy. pp. 35. DHHS (NIOSH) 

Publication No. 77-173, January 1977. http://www.cdc.gov/niosh/77-l73.html 

6Mulhausen, John R. and Damiano, Joseph. A Strategy for Assessing and Managing 

Occupational Exposures, 2nd edition. American Industrial Hygiene Association (AIHA Press): 1998, 

pp. 106-110.