There are three primary considerations for the design of small arms ranges:
1. The primary purpose for the ventilation of an indoor firing range is to remove from the respiratory zone of the occupants harmful contaminants created during the firing of a weapon. Exploding primers containing lead styphnate and friction from the lead slug against the gun barrel create airborne lead. There is also carbon monoxide as well as other contaminants created during the firing of a weapon.
2. The second and equally important reason for the properly designed and installed ventilation and control system is to keep the range at a negative pressure to the surrounding base building space. Contaminants created on a small arms range need to be contained within the range space. This will prevent the ingestion of contaminants as well as keeping the surfaces free of contaminants in non-range spaces of the base building.
3. The final purpose is to remove the smoke from the range for an improved line of sight to the targets.
The standards followed and required are summarized below:
NIOSH (National Institute of Occupational Safety and Health) has set the standard for range design. This suggested design criteria has been found to consistently produce conditions that keep exposure in the respiratory zone below the allowable limits for lead exposure.
The following is a summary of the EPA, NIOSH and OSHA standards as they apply to small arms range ventilation:
TITLE 40--PROTECTION OF ENVIRONMENT CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY PART 50--NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS--Table of Contents Sec. 50.12 National primary and secondary ambient air quality standards for lead. National primary and secondary ambient air quality standards for lead and its compounds, measured as elemental lead by a reference method based on appendix G to this part, or by an equivalent method, are: 1.5 micrograms per cubic meter, maximum arithmetic mean averaged over a calendar quarter. (Secs. 109, 301(a) Clean Air Act as amended (42 U.S.C. 7409, 7601(a))) On November 12th, 2008, the EPA issued a final rule that revised the NAAQS for lead and associated ambient air lead monitoring requirements strengthening the requirement to 0.15 micrograms per cubic meter as total suspended particles measured as a three-month rolling average. (73 FR 66964, codified at 40 CFR part 58)
NIOSH and OSHA:
Established by NIOSH, the performance intent for firing range ventilation systems shall meet all the requirements outlined as recommendations and design considerations in HEW publication no. (NIOSH) 76-130, dated December, 1975, entitled "Lead Exposure Design Considerations for Indoor Firing Ranges". This design standard prefers an air flow velocity of 75 feet per minute average on the empty range. This design has consistently provided for the compliance within the established federal standards for airborne inorganic lead concentration limits. When properly executed, lead concentrations are consistently maintained below the action level of 30 micrograms per cubic meter (30ug/m3) in an area where the limit shall not exceed 50 micrograms of lead per cubic meter (50ug/m3) of air over a time weighted average of eight hours as measured at the respiration zone of the shooters and the range officer when firing from the firing booths per OSHA 29 CFR. 1910.1025 and 1926.62.