Improving and Eliminating Regulations: Limit on Exposure to Diesel Particulate Matter in Underground Metal and Nonmetal Mines

What it does

• •Removes outdated provisions (30 CFR 57.5060(a), (b)(1), and (b)(2)) that contained interim and obsolete diesel particulate matter (DPM) exposure limits for underground metal and nonmetal mines.
• •Reserves the removed paragraph numbers to indicate the deletions are intentional.
• •Clarifies paragraph (b)(3) to establish that the current DPM exposure limit of 160 TC μg/m³ (published in the Federal Register on May 20, 2008) is the applicable standard for underground metal and nonmetal mines.

Why it matters

• •The removed provisions contained effective dates and exposure limits that are no longer relevant or in effect, creating regulatory confusion and unnecessary complexity without safety benefit.
• •MSHA states that removing these outdated requirements maintains the same level of protection for miners while streamlining compliance requirements for mine operators.
• •The final rule responds to Executive Order 14192 directing agencies to reduce unnecessary regulatory burdens.

Who is affected

• •Operators of underground metal and nonmetal mines subject to MSHA regulations.
• •Workers in underground metal and nonmetal mines who are exposed to diesel particulate matter.

What happens next

The rule becomes effective on December 14, 2026.