Honeywell North 7506N99 Respirator Prefilter

Honeywell North 7506N99 — N99 Snap-On Prefilter for North Gas Cartridges, NIOSH 42 CFR 84

The Honeywell North 7506N99 is a NIOSH 42 CFR 84 N99 snap-on prefilter that attaches to North N-series and 75SCL gas cartridges — providing 99% particle filtration efficiency, a higher-efficiency upgrade over the N95-class 7506N95. The 7506N99 is appropriate when N95 efficiency is insufficient for the particle hazard — particularly fine respirable dust (pharmaceutical API, fine crystalline silica, fine metal dust) in dry environments without oil aerosol. For oil mist environments, use the oil-resistant 7506R95 (R95) — the 7506N99 is not rated for oil aerosols. For the highest particle efficiency (99.97%) integrated with gas protection, combination cartridges such as the 75SCP100L provide P100 in a single unit.

Key Features

• NIOSH N99 — 99% non-oil particle efficiency: Higher filtration grade than N95 — N99 reduces particle penetration to 1% vs. N95's 5%, a 5× improvement in particle penetration. Appropriate when N95 efficiency is inadequate for the documented hazard concentration or particle size distribution
• Snap-on upgrade for gas cartridge users: Same attachment as 7506N95 — snaps directly onto N-series gas cartridges without removing them from the facepiece, upgrading particle protection to N99 level
• Not oil-resistant: N99 filter media is not rated for oil aerosols — oil exposure degrades efficiency. Use 7506R95 for oil mist environments
• Niche efficiency tier: N99 sits between N95 and P100 — it is rarely specified as a regulatory minimum and is most useful when N95 is borderline for documented exposure levels and P100 is considered overkill by IH assessment

Applications — When to Use the 7506N99

The 7506N99 is appropriate when N95 efficiency is insufficient for documented fine particle hazards in dry gas-cartridge environments:

• Fine pharmaceutical API dust: Active pharmaceutical ingredient manufacturing with very fine respirable particles in solvent-vapor environments — N99 provides more protection margin than N95 for fine aerosol size distributions
• Fine respirable crystalline silica: Operations with high-concentration fine silica (quartz, cristobalite) in dry environments where IH assessment determines N95 provides insufficient protection margin below the APF 10 ceiling
• Fine metal dusts with gas co-exposure: Cobalt, beryllium, or other high-toxicity fine metal dusts in operations also requiring gas cartridge protection — confirmed non-oil environments

Compatible Gas Cartridges (Snap-On)

The 7506-series prefilters snap directly onto Honeywell North N-series and 75SCL gas-only cartridges already installed on the respirator facepiece. They do not attach directly to P100 combination cartridges (7581P100L, 7583P100L, etc.) — those already contain integrated P100 filtration.

North Cartridge & Filter Line — Full Comparison

These prefilters snap onto North gas cartridges to add particle filtration. For integrated gas+particle protection, see the combination cartridges below.

Browse the complete lineup at Honeywell North Respirator Cartridges & Filters →

OSHA Compliance

• NIOSH approval required: All filters and cartridges in OSHA-mandated programs must be NIOSH approved under 42 CFR Part 84
• Hazard assessment required: OSHA 1910.134(d)(1) — filter/cartridge type must match the documented workplace hazard class
• Fit testing required: OSHA 1910.134(f)(2) — annual fit testing for any tight-fitting facepiece before operational use
• Filter replacement schedule: P-class and N/R-class filters are replaced when breathing resistance increases or visible contamination occurs — not on a fixed time schedule
• Medical evaluation prerequisite: OSHA 1910.134(e) — required before fit testing and before operational respirator use

Frequently Asked Questions

What is the difference between 7506N99 and 7506N95?

Both are non-oil-resistant NIOSH prefilters. N95 = 95% efficiency (5% penetration). N99 = 99% efficiency (1% penetration) — 5× less penetration than N95. Use 7506N99 when N95 efficiency is insufficient for the documented particle hazard at the confirmed exposure concentration.

Why would I use N99 instead of P100?

P100 (99.97%) provides higher efficiency than N99 (99%) in a combination cartridge format. However, if you already have gas cartridges in service and need only a particle efficiency upgrade over N95, the 7506N99 snap-on avoids replacing the gas cartridges prematurely. For new cartridge selection, combination cartridges with integrated P100 (e.g., 75SCP100L) are typically preferred over N99 prefilters.

Which cartridges does the 7506N99 snap onto?

N75001L, N75002L, N75003L, N75004L, and 75SCL. Not for P100 combination cartridges.

Can the 7506N99 be used for asbestos?

Yes — N99 meets and exceeds the N95 minimum for asbestos Class III and IV work. For Class I and II, full-face with P100 (APF 50) is required — use a P100 combination cartridge on a North 54001 or 760008A.

Is fit testing required?

Yes — OSHA 1910.134(f)(2). Annual fit testing for the facepiece before operational use.

Where can I find all North cartridges and filters?

Browse the complete lineup at Honeywell North Respirator Cartridges & Filters →