Another Year of Air Sampling: Keeping Workplaces Safe

© Enrique del Barrio – stock.adobe.com

Over the past year, air sampling has continued to be a useful tool for occupational hygienists and health and safety managers alike in managing the level of harmful airborne pollutants in the workplace. Still, exposure to airborne hazards in the workplace, such as gases, chemical vapors and dusts, can cause chronic respiratory illnesses and health issues. Approximately 30 million Americans are at risk of developing an occupational lung disease, with 30,000 annual deaths at least partially attributed to inhaled airborne hazards.1

The monitoring and classifications of airborne hazards have been under increased scrutiny from health and safety bodies to ensure workplaces can accurately quantify and manage risk to reduce this impact on life.

In the U.S., awareness of the dangers of silica dust has improved, re-igniting discussions of how to best protect workers from the invisible killer. This materialized in practice when the Mining Safety & Health Administration (MSHA) introduced its final ruling on silica’s permissible exposure limit (PEL) in the mining industry.

As a result, there has been a renewed emphasis on respiratory protection and air monitoring, with experts using both personal air sampling pumps and real-time, direct-monitoring instruments.

The latest generation of air sampling pumps increase efficiency in monitoring activity. Recent Bluetooth-enabled pumps and flow calibrators can automate the calibration process and save valuable time. (photo courtesy Casella, www.casellasolutions.com)

The Final Rule

In April 2024, the MSHA, part of the U.S. Department of Labor, announced a rule to lower the permissible exposure limit of respirable crystalline silica to 50 micrograms per cubic meter of air from 100 micrograms per cubic meter of air (μg/m3).2 Respirable crystalline silica is the most dangerous form of silica dust. Small enough to penetrate deep into the lungs, the dust is the cause of chronic lung diseases, such as silicosis and chronic obstructive pulmonary disease (COPD).

In addition to the reduction in exposure limits, the ruling also compelled employers to use engineering controls to minimize the risk of developing a lung condition and use dust samplings and environmental evaluations to monitor exposures.

This ruling replaced an outdated standard for respiratory protection to better protect miners against airborne hazards in light of advances in respiratory protection and monitoring practices.

Types of Monitors

With technological advancements in air sampling technologies, occupational hygienists and health and safety managers have the option to use both personal air sampling pumps and real-time instruments. When it comes to compliance, U.S. federal safety administrators employ air sampling pumps as the standard measure. Federal regulations require air sampling pumps because of the known and established methods, ensuring accurate data.

The latest generation of air sampling pumps increase efficiency in monitoring activity. Recent Bluetooth-enabled pumps and flow calibrators can automate the calibration process and save valuable time, increasing confidence in the calibration results that can be saved or emailed for inclusion in a report.

(photo courtesy Casella)

The pump is attached to a worker (typically on a belt), with a suitable sampling medium placed in their “breathing zone”—near the nose and mouth. Typically, this would be a filter housed in a sampling head, placed near the worker’s face and run over a sufficiently long time to establish an accurate concentration value, which can then be compared with the PEL. Each contaminant will have a dedicated “official method” which will advise on the type of filter and sampling head (or, for example, tube for vapors) for the given hazardous substance, along with the required flow rate and minimum run time.

These advancements also mean that sampling for an entire shift is now not necessary to quantify the immediate risk that individual workers are exposed to. Real-time instruments offer an alternative to this by using advanced techniques, such as light scattering to identify the relative size of the dust particles present. These monitors respond differently to varying dust types, meaning the data can only be considered as indicative, but ideal as a method for implementing and immediately verifying the effectiveness of controls to reduce the risk.

While real-time instruments cannot be used as compliant assessments of exposure, the monitors can be used for instant, continuous monitoring—allowing for immediate feedback on exposure levels that provides a dynamic picture of exposure levels over time, without the delays of using a sample that requires laboratory analysis.

How to Monitor

Discussions around the benefits of both personal air sampling pumps and real-time monitors have led employers to better understand the hazards present in the workplace and the types of monitoring that work best. (photo courtesy Casella, www.casellasolutions.com)

When deciding on an appropriate monitoring program to control the risks of airborne hazards to employees, employers must first quantify the types of risks that workers will be exposed to. Through a rigorous risk assessment, employers can identify the methodology and type of personal air sampling pump to use. Many pumps come intrinsically safe (IS) rated as standard for use in hazardous areas, but it is worth double-checking that your pump’s IS rating is appropriate for your facility to avoid any safety issues.

Dusts, for example, require a personal air sampling pump with an appropriate collection filter attached and sampling head, dependent on the size of the particles being measured. Respirable dusts require a cyclone head to draw air through, making use of centrifugal force to allow larger, only respirable particles to pass through onto the filter for subsequent analysis.

If sampling for vapors and gases, do consider a smaller, lightweight low-flow pump (<0.5 L/min), which is likely to be more acceptable than a medium-flow pump (1–5 L/min) equipped with a low-flow adaptor.

Before starting sampling, the entire sample train needs to be calibrated with a representative sample media; this process should be repeated at the end of the day to ensure there has been no major deviation in flow rate. Once calibrated, the pump is attached to the worker with the inlet placed in their breathing zone. The pump should be left running to collect a sample over the time prescribed by the method, and the concentration calculated as an 8-hour, time-weighted average, which the PELs are based on.

Conclusion

While there haven’t been many groundbreaking changes to air monitoring standards and regulations, those that came into effect in 2024 have been important and will save lives. Discussions around the benefits of both personal air sampling pumps and real-time monitors have led employers to better understand the hazards present in the workplace and the types of monitoring which work best to protect workers.

For compliance purposes, always employ the use of personal air sampling pumps. When unsure of which monitoring would be best suited to the workplace, it is recommended to consult external experts. IHW

Tim Turney is Global Marketing Manager at industrial hygiene equipment manufacturer, Casella. For more information, visit Casella’s website: https://www.casellasolutions.com/.


  1. Occupational Lung Diseases: Spectrum of Common Imaging Manifestations – PMC

  2. Department of Labor issues final rule reducing silica dust exposure, better protecting miners’ health from irreversible workplace illnesses | Mine Safety and Health Administration (MSHA)

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