Field Blanks: Why and When to Collect

Quality Assurance in Industrial Hygiene Sampling

Sound industrial hygiene sampling practice requires good quality assurance (QA) practices. QA is defined as:

the maintenance of a desired level of quality in a service or product, especially by means of attention to every stage of the process of delivery or production.

In essence, QA seeks to minimize error and at the same time evaluate sampling performance. Key QA practices include the following:

  • use of standard operating procedures (SOPs) for sample collection and analysis;
  • use of chain-of-custody and sample-identification procedures;
  • instrument standardization, calibration, and verification;
  • technician and analyst training;
  • sample preservation, handling, and decontamination; and
  • use of quality control (QC) samples such as field and transport blanks, duplicates, etc.

Quality Control: Why collect Field Blanks?

One of the methods of quality control in industrial hygiene sampling is through the collection and analysis of “control samples”. Control samples are typically in the form of blanks, duplicates, spiked samples, or split samples. Blanks can be further refined into several categories including: field blanks, transport blanks & media blanks.

  • Field Blanks – determine if there was contamination during the collection stage
  • Transport Blanks – determine if there was contamination during the shipping stage
  • Media Blanks – determine if the media itself is contaminated

Therefore, if quality assurance is our goal, and the use of field blanks (i.e. quality control) are one of our methods for ensuring QA.

How to Collect a Field Blank

Field blanks are clean sampling media and are handled in exactly he same manner as the samples you are collecting, except:

  • No air is drawn through them (for air samples), or no surface is wiped with them (for surface / wipe samples),
  • They are opened and closed quickly in the sampling area and then resealed, and
  • Accompany the actual samples through every stage of the sampling process.

How Many Field Blanks Should I Collect?

The number of field blanks you should collect should be based on a few considerations (in order of importance), including: sample method, reason for sampling, and budget considerations. The sampling method (e.g. NIOSH or OSHA) should dictate how many field blanks you should collect (see image below), based on the number of samples you collect. Typically, the recommended practice is 10% of your number of samples.

What do I do if the Contaminant is Detected in the Field Blank?

If a contaminant is found on the field blank, the field blank contaminant is typically going to be reported as a mass, and not a concentration (remember, no air volume was drawn through the field blank sample). The mass of contaminant found on the field blank will be subtracted from that found on the actual sample before dividing by the air volume to determine the mass concentration of the contaminant. Additionally, it’s important to note the sampling methods often have a permissible limit of contaminant on the field blank. If this level is exceeded, the samples should be discarded and sampling repeated.

If we do not account for the field blank contamination, the industrial hygienist runs the risk of the reported results being biased high, which can lead to: additional sampling or the implementation of potentially unnecessary controls.

Why Don’t Industrial Hygienists Take Field Blanks?

Practicing industrial hygienists don’t take field blanks for several reasons, including: budgets (10% extra costs for “worthless” blanks can seem excessive), improper training, unfamiliarity with the sampling methodology, and they don’t want competence questioned. However, none of these reasons justify forgoing good QA/QC practices to ensure the integrity of your samples.

Adequate Face Velocity for Laboratory Hoods

Multiple organizations have adopted laboratory hood safety standards to determine the effectiveness of a hood in limiting occupational exposure.  One such measure of determining the effectiveness of the hood is by measuring the speed of air entering the hood (i.e. the face velocity).  While face velocity is not the only test method for determining if a hood has the ability to adequately contain the contaminants (see ANSI/ASHRAE 110-1995 Method of Testing Performance of Laboratory Fume Hoods), it is the only performance standard cited by the following organizations.

  • OSHA – General air flow should not be turbulent and should be relatively uniform throughout the laboratory, with no high velocity or static areas (194, 195); airflow into and within the hood should not be excessively turbulent (200); hood face velocity should be adequate (typically 60-100 lfm)
  • NIOSH – The current consensus of the literature is that the average face velocity for a laboratory chemical hood should be in the range of 80–120 ft/min
  • Cal OSHA – The exhaust system shall provide an average face velocity of at least 100 feet per minute with a minimum of 70 fpm at any point, except where more stringent special requirements are prescribed
  • ANSI/AIHA Z9.5-2003 – Design face velocities for laboratory chemical hoods in the range of 80-100 fpm (0.41-0.51m/s) will provide adequate face velocity for a majority of chemical hoods. Hoods with excellent containment characteristics may operate adequately below 80 fpm (0.41 m/s) while others may require higher face velocities. (more…)

NIOSH Updates List of Hazardous Drugs Used in Healthcare

The National Institute for Occupational Safety and Health (NIOSH) Alert: Preventing Occupational Exposures to Antineoplastic and Other Hazardous Drugs in Health Care Settings was published in September 2004. In Appendix A of the Alert, NIOSH identified a sample list of major hazardous drugs. The list was compiled from infor-mation provided by four institutions that have generated lists of hazardous drugs for their respec-tive facilities and by the Pharmaceutical Research and Manufacturers of America (PhRMA) from the American Hospital Formulary Service Drug Information (AHFS DI) monographs. This update adds 21 drugs to the original list in the 2004 Alert. These additions are new drugs or existing drugs that had new warnings from 2004 to 2007.

To download a copy of this document, click HERE ().


NIOSH Offers Free Health Hazard Evaluations

Much in the same way that OSHA offers free onsite health and safety consulting services, NIOSH has a similar program for workplaces.  A Health Hazard Evaluation (HHE), offered by NIOSH, is a study of hazardous materials or harmful conditions in the workplace.  Taking the form of an interview, site visit and evaluation, or helpful information, the HHE provides the NIOSH findings and/or recommendations to the employer in the effort to reduce the hazard of issue.

To request a NIOSH HHE, click HERE.

1. When to request an HHE from NIOSH

You are an employee, employee representative, or employer and the following apply:

  • Employees have an illness from an unknown cause.
  • Employees are exposed to an agent or working condition that is not regulated by OSHA.
  • Employees experience adverse health effects from exposure to a regulated or unregulated agent or working condition, even though the permissible exposure limit is not being exceeded.
  • Medical or epidemiological investigations are needed to evaluate the hazard.
  • The incidence of a particular disease or injury is higher than expected in a group of employees.
  • The exposure is to a new or previously unrecognized hazard.
  • The hazard seems to result from the combined effects of several agents.

2. When to request help from the OSHA Consultation Program

You are a small business owner and you want:

  • assistance in recognizing hazards in your workplace.
  • suggestions or options for correcting safety and health issues.
  • assistance in developing or maintaining an effective safety and health program.
  • to reduce workers compensation cost and improve employee morale..

The OSHA On-site Consultation Program:

  • is a free service.
  • is delivered by state (and territorial) governments using well-trained safety and health professionals.
  • is separate from enforcement.
  • is confidential. The company’s name, and any other identifying information provided about the workplace, plus any unsafe or unhealthful working conditions that the consultant uncovers, will not routinely be reported to OSHA enforcement personnel.
  • does not issue and citations, penalties, or fines.
  • will provide you a confidential, written report that summarizes the consultant’s findings.
  • requires the correction of hazards identified by the consultant(s).
  • under specific circumstances, employers with exemplary safety and health programs can be recommend for recognition and provided with an exclusion from general schedule inspections.

Worksheet: Analyzing Lifting Operations

Washington’s Department of Labor and Industries has created a worksheet based upon the NIOSH Lifting Equation to determine if a lift operation exceeds the recommended limits.  A copy of this worksheet can be found here:

  Worksheet: Ergonomics Calculations (40.8 KiB, 1,303 hits)

.  If you are unfamiliar with the NIOSH Lifting Equation, a good resource is the Revised NIOSH Lifting Equation Document.

LI = the relative estimate of the physical stress associated with a manual lifting job


Sources:  eLCOSH & NIOSH

Black Lung Cases on the Rise

minersThe Wall Street Journal has written an article based upon findings of the National Institute for Occupational Safety and Health (NIOSH) indicating a rise in the occurrences of black lung in miners.  Based upon the findings of NIOSH, approximately 9% of miners with 25+ years of experience were positive for black lung in 2005 and 2006, which represents a doubling of  the percentage of those with black lung in the 1990’s.  Black lung is serious health and safety issue in mines, even more so than mine accidents, with more than 10,000 dead since 2000, versus less than 400 from mine accidents.


New monitoring equipment may be potentially introduced by MSHA (Mine Safety and Health Administration) to allow real-time, continuous monitoring of an employee’s dust exposure, versus the standard 8-hour periodic exposure monitoring.  The real-time monitoring would also take into account longer work shifts, which is quite common in the mining industry.

For more information on black lung, NIOSH has produced a video entitled, Faces of Black Lung

View Part 2 after the break:

Online Tool: Is Your Hearing Protection Providing Adequate Attenuation?

hearing_protectionAn extremely useful field tool to determine if you are achieving adequate attenuation with your hearing protection has been devised by NIOSH.  Have you used this in your workplace?  How successful has it been?  Let us know in the comments section of this post.

Loud noise can permanently damage your hearing. It especially affects the sounds that help you understand speech.

Earmuffs, earplugs, and other hearing protection devices can reduce your risk of hearing loss, but only if you get a good fit and wear them properly.

Follow the instructions for the sound player on the right side of this page to perform a quick test of whether you are getting at least a minimal 15 decibel (dB) level of protection.

How it Works

The test sounds are bands of random noise with a center frequency of 1000 Hz. This is the same type of sound used in standard hearing protector ratings including the “American National Standard Methods for Measuring the Real-Ear Attenuation of Hearing Protectors” (ANSI S12.6). Both tracks are the same, but the second track is 15 decibels (dB) louder than the first. Most hearing protectors will block or “attenuate” sound by more than 15 dB if they are the right size and shape to fit your ears and are worn correctly. A sound that is barely audible at your threshold of hearing without hearing protection should be inaudible though hearing protection even if it’s boosted by 15 dB.

Online or Offline Testing:

You can also download the test sounds to check your hearing protection offline with an MP3 player or computer multimedia player. Download or play online, these two tracks:

Track 1: Without Hearing Protection NIOSH QuickFit Without HPD
Track 2: With Hearing Protection NIOSH QuickFit With HPD

For online testing, click the links, goto the .mp3 page, then click the file. Quicktime (or the program you have installed on your computer) will play the file. To download the files for offline testing, right-click the link and choose “Save File As…” or similar selection from the menu.

Continue Reading for the Instructions…


EPA Hosts Webinar on Spray Foam Initiative

spray_foamThe Environmental Protection Agency hosted over 300 spray foam industry professionals and concerned viewers in an online seminar to introduce the agencies’ collective concerns and involvement with the safety practices and health risks associated with the handling, application, and life cycle usage of spray polyurethane foam.

Involvement included:

  • EPA
  • OSHA
  • CPSC
  • The Center for Polyurethanes Industry, and
  • Spray Polyurethane Foam Alliance (SPFA) trade associations

The SPFA reports market growth of up to 40% since 2004. The EPA sited a report indicating that over 400 million pounds of polyurethane foam were consumed in North America during 2008.

The presentation several goals of the EPA initiative:

  • Improve Availability of Safety Information
  • Communicate Best Safety Practices
  • Address Inaccurate and False Marketing Claims
  • Exposure Assessment

According to information made by the EPA, another webinar will be held regarding Spray Foam due to demand.  Stay tuned to for more information.


Mary Cushmac, from the EPA opened up the meeting with comments about the current situation in the industry as it relates to the government agency’s perspective. She indicated that both the A-side product and B-side products contain both primary and intermediate chemicals of concern, especially if they are mis-handled, or applied incorrectly.


Ergonomics for Construction Workers

simple_solutions_ergonomics_construction_workersThis booklet, published by NIOSH, is intended for construction workers, unions, supervisors, contractors, safety specialists, human resources managers-anyone with an interest in safe construction sites. Some of the most common injuries in construction are the result of job demands that push the human body beyond its natural limits.Workers who must often lift, stoop, kneel, twist, grip, stretch, reach overhead, or work in other awkward positions to do a job are at risk of developing a work-related musculoskeletal disorder (WMSD). These can include back problems, carpal tunnel syndrome, tendinitis, rotator cuff tears, sprains, and strains.iron worker

To aid in the prevention of these injuries, this booklet suggests many simple and inexpensive ways to make construction tasks easier, more comfortable, and better suited to the needs of the human body.

Example of a “simple solution.” This ironworker uses a tool that automatically ties rebar with the pull of a trigger. The extended handle lets him work while standing upright. No leaning, kneeling, stooping, or hand twisting are necessary.

Did you know … ?

  • Construction is one of the most hazardous industries in the United States.
  • The number of back injuries in U.S. construction was 50% higher than the average for all other U.S. industries in 1999 (CPWR, 2002).
  • Backaches and pain in the shoulders, neck, arms, and hands were the most common symptoms reported by construction workers in one study (Cook et al, 1996).
  • Material handling incidents account for 32% of workers’ compensation claims in construction, and 25% of the cost of all claims. The average cost per claim is $9,240 (CNA, 2000).
  • Musculoskeletal injuries can cause temporary or even permanent disability, which can affect the worker’s earnings and the contractor’s profits.


Approved NIOSH N-95 Respirators

n95_respiratorThe N95 respirator is the most common of the seven types of particulate filtering facepiece respirators. This product filters at least 95% of airborne particles but is not resistant to oil.

View the complete list of approved N-95 respirators HERE

A list all of the seven types of particulate filtering facepiece respirators is shown below:

Class Description
N95 Filters at least 95% of airborne particles. Not resistant to oil.
N99 Filters at least 99% of airborne particles. Not resistant to oil.
N100 Filters at least 99.97% of airborne particles. Not resistant to
R95 Filters at least 95% of airborne particles. Somewhat resistant
to oil.
P95 Filters at least 95% of airborne particles. Strongly resistant
to oil.
P99 Filters at least 99% of airborne particles. Strongly resistant
to oil.
P100 Filters at least 99.97% of airborne particles. Strongly resistant
to oil.

Current State of US Worker Health & Safety

work_fatalities_2007The entire NIOSH document can be found HERE

In 2008 more than 145 million people in the U.S. were employed in the civilian workforce. Every day, approximately 9,000 workers are injured on the job and 15 workers die from a fatal workplace injury. Work-related illness claims the lives of about another 135 workers and retirees daily. According to the Bureau of Labor Statistics (bls), 5,657 workers died from work-related injuries and more than 4 million nonfatal injuries and illnesses were reported in 2007. The economic impact of work-related injury and illness has been estimated to be $171 billion annually, the same as cancer or cardiovascular disease and much greater than the burden from hiv/aids or Alzheimer’s disease. In 2006 employers spent an estimated $87.6 billion on wage payments and medical care for workers hurt on the job.

Addressing workplace safety and health poses numerous challenges. First, the composition of the U.S. workforce is becoming increasingly diverse; it is becoming older, more racially and ethnically diverse, and more women are entering the workforce. These changes reflect the changing social and demographic characteristics of the country but also produce new safety and health issues. It has become clear that certain populations experience an increased burden of disease, disability, and death. These populations also frequently have less access to quality healthcare.

Moreover, U.S. workplaces are rapidly evolving, changing the way work is organized. Jobs in our economy continue to shift from manufacturing to services, with service-providing industries now employing about 80 percent of all workers. Longer hours, compressed work weeks, shift work, reduced job security, and part-time and temporary work are realities of the modern workplace and are increasingly affecting the health and well-being of workers and their families. In addition, new chemicals, materials, processes, and equipment with new potential occupational risks are being developed and marketed at an ever-accelerating pace.

The acute and long-term effects of work-related injury, illness, and death translate into tremendous economic and emotional costs to society. Data show that when interventions, such as safe work practices and engineering controls, are based on sound scientific research the burden of injury and illness is significantly reduced. Through its Research-to-Practice (r2p) initiative, niosh works closely with its partners to move research findings and technologies out of the Institute and into the workplace, and to promote the diffusion of products and information in an effort to protect workers and reduce cost to employers, workers, their families, and society as a whole.

NIOSH Pocket Guide App now on the IPhone

niosh_pocket_guide_iphone_appDangerous Decisions LLC today is proud to introduce the NIOSH Pocket Guide 1.0, their new chemical hazards database for iPhone and iPod touch. Designed specifically to take advantage of the iPhone’s interface, the NIOSH Pocket Guide (National Institute for Occupational Safety and Health) gives safety professionals immediate access to crucial information on all of 677 chemicals in the database including all the resources of the NIOSH Pocket Guide and much more.

The NIOSH Pocket Guide to Chemical Hazards (NPG) is intended as a source of general industrial hygiene information on several hundred chemicals (with their classes) for workers, employers, and occupational health professionals. It is a must-have for every safety professional, industrial hygienist, chemist, or collage student seeking a safety degree, and a valuable reference guide for anyone that works with hazardous chemicals in the workplace or at home.

The information found in the NIOSH Pocket Guide help users recognize and control occupational chemical hazards. The NPG does not contain an analysis of all pertinent data. Rather, it presents key information and data in abbreviated or tabular form for chemicals or substance groupings (e.g. cyanides, fluorides, manganese compounds) that are found in the work environment.

Designed as a stand-alone application, the Pocket Guide includes the chemical names, synonyms, trade names, conversion factors, CAS, RTECS, and DOT numbers, recommended exposure limits (NIOSH RELs), Occupational Safety and Health Administration (OSHA) Permissible Exposure Limits (PELs), and NIOSH Immediate Dangerous to Life and Health values (NIOSH IDLHs) (documentation for those values). The guide also features a physical description of the agent with chemical and physical properties, measurement methods, personal protection and sanitation recommendations, respirator recommendations, as well as great information on health hazards including route, symptoms, first aid and target organ information.

niosh_iphone_app_indexFeature Highlights:
* Chemical names, synonyms, trade names, conversion factors, CAS, RTECS, and DOT numbers
* NIOSH Recommended Exposure Limits (NIOSH RELs)
* Occupational Safety and Health Administration (OSHA) Permissible Exposure Limits (PELs)
* NIOSH Immediate Dangerous to Life and Health values (NIOSH IDLHs) (documentation for those values)
* A physical description of the agent with chemical and physical properties
* Measurement methods
* Personal protection and sanitation recommendations
* Respirator recommendations
* Information on health hazards including route, symptoms, first aid and target organ information
* Search by Chemical Name, Case number, Synonym and Trade Names
* Access all the appendixes
* Save critical information about regularly worked-with chemicals in the Notes section
* Use the convenient Email function to send Chemical guides and notes to associates
* Load onto all generations of iPhone and iPod Touch
* Download to iPhone devices without a wireless connection

“As a safety professional, when emergencies with hazardous chemicals occur, I was frustrated spending valuable time compiling critical response information from multiple sources to get the field a comprehensive safety plan” said Chester Karella, founder and CEO of Dangerous Decisions LLC. “There had to be a better way. My new NIOSH Pocket Guide App allows all the critical information to be quickly deployed to the field from a single application.”

System Requirements:
* iPhone or iPod Touch 3.0 or later

Pricing and Availability:
NIOSH Pocket Guide 1.0 is only $9.99 (USD) and available exclusively through the App Store in the Reference category. Free updates as Chemical exposures recommendations change will be made available. Review copies are available upon request.