According to the American Lung Association, occupational lung disease is the nation’s leading cause of work-related illness, with occupational asthma its most prevalent manifestation (possibly almost as much as a quarter of new-onset US asthma cases are attributable to occupational exposures).1

Occupational lung disease occurs because workers are exposed to fumes and airborne fibers from harmful chemicals and agents. These include asbestos, cadmium, cotton dust, polyurethane, and formaldehyde. The Occupational Safety and Health Administration (OSHA) requires the implementation of worker health-monitoring programs by employers whose production processes or environments create exposures to such chemicals and agents. Many employers voluntarily provide this type of health monitoring simply as a matter of good occupational health practice.

Regardless of how they come about, these monitoring programs usually include, or are designed around, spirometry testing.

“Spirometry is the single best test for detecting nonmalignant lung diseases due to occupational exposures,” contends Paul Enright, MD, professor of medicine at the College of Public Health at the University of Arizona, Tucson, and a long-time member of the American Thoracic Society’s Pulmonary Function Testing Standards Committee. “Spirometry may confirm asthma in workers during the period of time when they are experiencing symptoms. Spirometry also is the only test for detecting COPD; and, while chest x-ray surveillance is mandated for miners, sandblasters, and others at risk of developing a pneumoconiosis due to high dust exposures, spirometry can supplement these chest x-rays for detecting a loss in lung function due to a restrictive lung disease that is slowly developing. Moreover, many employers who want to improve worker safety provide preplacement spirometry and annual spirometry testing for almost all of their employees, even if not mandated by law.”

Health Protection

For readers who are not familiar with the procedure, spirometry is the most common of the pulmonary function tests. It measures the volume and/or flow of inhaled and exhaled air. Spirometry is, of course, performed using a spirometer, of which there are two basic forms: volumetric (such as the water bell and bellows-wedge types) and flow measuring (which includes the Fleisch pneumotach, screen pneumotach, rotating vane turbine, pitot tube, and hot-wire anemometer varieties). Good practice includes placement of a filtered mouthpiece over the spirometer to help thwart the spread of bacteria.

In administering a spirometry test, the patient is asked to take the deepest possible breath, then exhale for at least 6 seconds with as great a force as can be mustered. When assessing for upper airway obstruction, the test might include a deep inhalation fast on the heels of the exhalation. Nose clips sometimes are applied to ensure that all the exhaled air flows through the mouth only.

Beyond the broad goal of protecting health, spirometry testing in the workplace is intended to reduce absenteeism and its attendant direct and indirect costs. These can include the education and training of replacement hires, health care expenses related to treatment, and outlays for workers’ compensation premiums. “Spirometry is part of the surveillance process, and the surveillance process is key to being able to reduce workplace exposures to harmful agents,” says Lu-Ann F. Beeckman-Wagner, PhD, research physiologist assigned to the Workforce Screening and Surveillance Team, Surveillance Branch, Division of Respiratory Disease Studies, National Institute of Occupational Safety and Health (NIOSH), in Morgantown, WVa. “OSHA has mandated for decades now the annual spirometry testing of workers exposed to coal dust, cotton dust, [and] benzene … and for medical clearance exams for workers who must wear protective respirators on the job.”

Threats Keep Coming

Eileen Storey, MD, MPH, acting chief of the Surveillance Branch, Division of Respiratory Disease Studies at NIOSH, notes that among the most common causes of occupational asthma is exposure to a chemical group called isocyanates. “These are the building blocks of polyurethane—meaning they’re very common in paints, finishes, soft-seating support systems, and mattresses,” she says, “and, right now, one of the more common causes of new asthma is exposure to cleaning agents using so-called citrus compounds. The irony is that citrus compounds were introduced as a replacement for toxic chemicals like chlorinated hydrocarbons—solvents that formerly were used for everything from wax stripping to general mop-up, but those turned out to be toxic to the liver, and some caused cancer. Unfortunately, citrus compounds may be highly allergenic. So, although workers who use cleaning agents no longer are threatened with liver poisoning, some are instead developing asthma.”

Spirometry is a reliable gauge of lung health, but many factors can influence test results.

Topping the list of factors is patient cooperation. If a patient fails to follow technician instructions and does not make the proper effort during testing, measures of volume and flow can be significantly off the mark—either too high or too low—thereby leading test interpreters to draw the wrong conclusions.

“The American College of Occupational and Environmental Medicine [ACOEM] has made available a position statement that lists all the factors that can affect spirometry results [see the organization’s Web site at],” says Lu-Ann F. Beeckman-Wagner, PhD, of the Workforce Screening and Surveillance Team, Surveillance Branch, Division of Respiratory Disease Studies, National Institute of Occupational Safety and Health (NIOSH), in Morgantown, WVa. “Part of the technician’s training is [the ability] to recognize and control as many of these factors as possible. This training is therefore critically important.”

Beeckman-Wagner’s organization is helping address this concern by administering a national spirometry training program. “NIOSH has developed a roster of approved providers who teach the course for us,” she says. “These providers conduct the course throughout the year and in locations all across the country. Our [Web site] shows who these providers are. It also offers a calendar of when the courses are taught. NIOSH approves the curriculum, we have standardized test instruments that students must pass in order to receive a certificate, we do site visits to make sure the instructors are teaching what they say they are, and we go through a renewal process every 5 years because the technical information can change quickly and we want to make sure everyone is up to date as best possible.

“The National Fire Protection Association requires all technicians who do spirometry on firefighters to take a NIOSH course. The Occupational Safety and Health Administration requires it for technicians in the cotton industry.”

In January 2009, NIOSH began offering a refresher training course for spirometry technicians who have been previously certified.


Enright, who while at the Mayo Clinic helped a major chemical manufacturer develop an annual spirometry surveillance program at 30 of its US plants, adds that one of the most recent groups of employers to find it necessary to begin spirometry testing is the flavorings industry. “It was observed that workers involved in the production of microwave popcorn were developing severe, fixed-airway obstruction conditions due to their exposure to the butter flavoring ingredient,” he says.

Significantly, the universe of workplaces where harmful fumes, fibers, and other particulates lurk has not been fully mapped—nor might it ever be. “One reason is that problematic materials and chemicals are being developed as part of industrial processes,” says Beeckman-Wagner. “I can offer nanotubes as an example: We know some information about how they affect the lungs, but we don’t know everything. [Consequently], NIOSH is always trying to identify these problems and then come up with solutions to prevent harm to workers.”

Taking the First Step

Assume that a company developed an interest in conducting spirometry testing of all its workers as part of an occupational lung-disorders prevention strategy. What might that company need in the way of equipment, clinical personnel, protocols, databasing, and training? How would this same company put to optimal use the data collected from spirometry testing of its employees?

“The first step would be to conduct a review of the work being done by the employees to figure out who should be eligible for testing,” says Beeckman-Wagner. “This is usually overseen by an occupational medicine physician in conjunction with an industrial hygienist. From there, the physician creates a surveillance protocol that defines the initial testing that needs to be done. This can include medical and occupational histories, physical exams, and other tests, of which spirometry is one. The surveillance protocol also defines how frequently the tests should be performed.

“Once these issues are settled, the next step is to acquire a spirometry system, which, in addition to the testing device, will include a calibration syringe, thermometer, barometer, and disposable supplies. Whatever system is selected, though, it must meet the American Thoracic Society minimum specifications.

“The tests are then performed. Once these data are collected, the results are supplied to the occupational medicine physician [who] will review them, making sure they are of proper quality. Satisfied that they are, [the physician] then interprets them.”

Beeckman-Wagner asserts that while spirometry monitoring programs can be accomplished with a paper-based charting system, it is much easier and more efficient to use an electronic database. “The optimal use of the data is to have the physician conduct a periodic review of the trends and to ascertain how the data change over time to see if those changes follow certain patterns with respect to the tasks of the workers or to the agents,” she says. “If we do see a drop in lung function, how do we evaluate whether it is significant or not? The trend can be plotted by computer, but it’s left to the physician to determine whether the drop is significant. NIOSH recently introduced a software program called SPIROLA—Spirometry Longitudinal Data Analysis—that helps a physician plot the trends but also gives additional information in making the final determination as to whether the change is or isn’t significant.”

A beta version of SPIROLA is downloadable from the NIOSH Web site:

The frequency of this review process varies with the degree of risk posed by the hazardous exposure. “In some cases, it occurs yearly, while in less risky instances it might be less frequent,” says Storey. “Where there is a young workforce and the intensity of exposure is not particularly great, you might even find that reviews take place once every 3 years.”

Signs of Success

Challenges exist for those companies that utilize spirometry for their surveillance programs. One is the often poor quality, causing high false-positive rates, which unfortunately is common in occupational settings. “Some companies respond to the bad news of apparently high abnormality rates by ‘burying the results’ or, worse, by sending the manufacturing process to a developing country where there are no workplace safety rules,” says Enright. “The worst thing they can do is discontinue the program.”

Enright says the appropriate response to dismal results is to seek the help of an experienced pulmonary function testing consultant. “Have that specialist review the entire program and recommend corrective action,” he advises.

The task of actual testing with a spirometer in the occupational setting belongs in normal circumstances to a nurse, although medical assistants and clinical technicians, such as respiratory therapists, under the supervision of that nurse are also acceptable. However, the most important role for respiratory therapists with regard to occupational lung disease surveillance and prevention is that of educator. “We need RTs to help spread awareness of potential work-related health problems and to promote the importance of good-quality spirometry testing,” says Beeckman-Wagner.

With or without respiratory therapists getting the word out, occupational spirometry programs appear to be having an effect.

“We’re seeing considerable success, particularly for the hazards that are regulated by OSHA,” says Beeckman-Wagner. “The key to success is being able to identify these disease processes at the earliest possible time. In order to do this, we have to be able to identify small but significant changes in lung function and this requires very high-quality data. Companies need accurate equipment and technicians properly trained to collect valid spirometry data. We’re seeing much progress in these areas as well.”

Rich Smith is a contributing writer to RT. For further information, contact [email protected].


  1. Lung disease data at a glance: occupational lung disease. American Lung Association fact sheet. Available at: Accessed March 20, 2009.