Powered Air Purifying Respirators (PAPRs) for Protection from Respirable Dust in Underground Mines

Our plain-English summary of Powered Air Purifying Respirators (PAPRs) for Protection from Respirable Dust in Underground Mines, by L. Sanchez Gonzalez, A. Ranjan Kumar, B. Arnold (Mining, Metallurgy & Exploration, 2025).

The study

• Authors: L. Sanchez Gonzalez, A. Ranjan Kumar, B. Arnold
• Journal: Mining, Metallurgy & Exploration
• Published: 2025;42(5):2743-2759
• Type of article: Review
• Read it: PubMed · Publisher · Free full text

Abstract

Underground mining operations use several remedial measures to alleviate the miners' exposure to respirable dust. This includes maintaining the ventilation airflow, deploying scrubbers on equipment, and using water sprays to move air and dust away from the miners and to capture them. Despite these engineering controls, recent research shows an increased occurrence of exposure-related issues in the impacted miners. Masks and other PPE devices are considered the least preferred in the hierarchy of controls. However, they show a high protection factor if designed properly and according to recommendations. A Powered Air Purifying Respirator (PAPR) is a battery-operated personal scrubber that has found widespread application in industries. This respirator uses a blower to move air through a high-efficiency particulate air (HEPA) filter, delivering the purified air to the user. Its popularity is attributed to its high protection efficiency. This paper summarizes the current applications and evaluation methods of PAPRs. It strongly recommends their usage in underground mines to reduce the risk of mine dust lung diseases such as pneumoconiosis, asbestosis, silicosis, and others that do not have any conclusive treatment. While the high efficiency of the respirators has been demonstrated, we recommend further studies to investigate the unique challenges associated with their use in underground mines. Therefore, this paper also presents computational fluid dynamics (CFD) simulations as a tool to understand the performance of PAPRs in underground tunnels, which could help to understand not only the efficiency, but also the challenges associated with their implementation.

© The Author(s) 2025.

In plain English

This article reviewed published studies, standards and regulatory documents on powered air purifying respirators (PAPRs), battery-powered respirators that blow HEPA-filtered air to the wearer. The authors did not describe how they chose the studies. They summarized how respirator protection is measured, PAPR use in several industries, and computer airflow-modeling (CFD) studies by others. The article did not report new simulations of its own. The authors reported that PAPRs can achieve higher protection than masks such as the N95. In one reviewed study, leakage under different wearing conditions was between 0.18 and 0.42% for a PAPR and between 1.82 and 10.92% for a replaceable particulate respirator. Reviewed drawbacks included difficulty communicating, blower noise, and leakage when a wearer's breathing outpaced the blower. PAPRs in coal mines require MSHA approval, and several operators had petitioned to use them. The authors noted very few workplace and CFD studies and called for more. They concluded that, although PAPRs are not required by law, the industry should encourage mine operators to adopt them as an additional layer of protection for miners. Asbestos appeared only in passing.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Review of published literature, standards and regulatory documents (narrative review; no search or selection method described)
• Who was studied: Published studies and documents on PAPRs used in mining (mainly US underground coal mines), healthcare, and other industries; the number of studies reviewed and how they were selected are not stated
• Exposure: Respirable dust in underground mines, especially coal mine dust, and protection from it with PAPRs. Asbestos is mentioned only in passing: as a standard in a table of exposure limits (100,000 fiber/m3) and in a citation to other studies on fiber size. No asbestos-specific respirator data are reported.
• Main results:
  • Across the studies reviewed, the authors reported that PAPRs can achieve higher protection than other mask types such as the N95
  • In one reviewed study (the article's reference 75), a Koken replaceable particulate respirator (RPR) was compared with a Koken PAPR under recommended and non-recommended wearing conditions. Leakage was between 1.82 and 10.92% for the RPR and between 0.18 and 0.42% for the PAPR. A second reviewed study of the same two respirators reported fit factors rather than leakage.
  • Reviewed studies described leakage into the mask when the wearer's breathing needs exceed the blower's airflow (called over-breathing)
  • Drawbacks identified in the reviewed studies included difficulty communicating, being unable to wear other equipment with the mask, and blower noise
  • US underground coal mine operators had petitioned to use specific PAPR models (the 3M TR-800 and CleanSpace models); PAPRs in coal mines require MSHA approval and must be intrinsically safe
  • The authors found very few CFD simulation studies of PAPR performance
• The authors' conclusion: The authors concluded that their literature review established PAPRs' ability to supply clean air to the user. They stated that, although PAPRs are not required by law, the industry should encourage mine operators to adopt them as an additional layer of protection for miners.
• Limitations the authors state:
  • The authors stated there are very few studies measuring workplace protection factors for respirators, and they recommended more such studies so that there is industry-specific evidence
  • The authors noted that few CFD studies of PAPRs exist and stated that further research is needed to improve these models and develop test setups

Topics

Medical terms in this study, explained in our Lexicon: Respirator, Engineering Controls, Assigned Protection Factor, Pneumoconiosis, Silicosis.

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