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Compliance · Cal/OSHA

Cal/OSHA Permissible Exposure Limits (8 CCR §5155, Table AC-1)

Occupational: legal limit (California), 8-hour TWA unless noted

California sets its own workplace exposure limits in 8 CCR §5155, Airborne Contaminants, whose Table AC-1 lists a permissible exposure limit (8-hour TWA), a short-term exposure limit (15-minute), and a ceiling for each regulated substance. Cal/OSHA has updated its table far more recently than federal OSHA, so many values are stricter. Examples include carbon monoxide at 25 ppm with a 200 ppm ceiling (federal: 50 ppm); ozone at 0.1 ppm with a 0.3 ppm STEL; sulfur dioxide at 2 ppm with a 5 ppm STEL; hydrogen sulfide at 10 ppm with a 15 ppm STEL and a 50 ppm ceiling; and nitrogen dioxide with a 1 ppm STEL.

Schedule a callConfigure Cal/OSHA PEL Monitoring

Limit values

Cal/OSHA PEL Limit Values

Every value Cal/OSHA publishes for the 13 parameters below, with its averaging period, as the standard states it.

Carbon Monoxide (CO) Gases & VOCs
25 ppm 8-hour TWA (PEL)
200 ppm Ceiling
Carbon Dioxide (CO₂) Gases & VOCs
5000 ppm 8-hour TWA (PEL)
30000 ppm STEL
Hydrogen Sulfide (H₂S) Gases & VOCs
10 ppm 8-hour TWA (PEL)
15 ppm STEL
50 ppm Ceiling
Sulfur Dioxide (SO₂) Gases & VOCs
2 ppm 8-hour TWA (PEL)
5 ppm STEL
Nitric Oxide (NO) Gases & VOCs
25 ppm 8-hour TWA (PEL)
Nitrogen Dioxide (NO₂) Gases & VOCs
1 ppm STEL
Ozone (O₃) Gases & VOCs
0.1 ppm 8-hour TWA (PEL)
0.3 ppm STEL
Ammonia (NH₃) Gases & VOCs
25 ppm 8-hour TWA (PEL)
35 ppm STEL
Chlorine (Cl₂) Gases & VOCs
0.5 ppm 8-hour TWA (PEL)
1 ppm STEL
Mercury (Hg) Gases & VOCs
0.025 mg/m³ 8-hour TWA (PEL)metallic and inorganic mercury
0.1 mg/m³ Ceilingmetallic and inorganic mercury
Hydrogen Chloride (HCl) Gases & VOCs
0.3 ppm 8-hour TWA (PEL)
2 ppm Ceiling
Hydrogen Fluoride (HF) Gases & VOCs
0.4 ppm 8-hour TWA (PEL)as F
1 ppm STELas F
BTEX / speciated VOC Gases & VOCs
1 ppm 8-hour TWA (PEL)benzene (see also section 5218)
5 ppm STELbenzene

Who it applies to

Who Must Comply

Employers in California. Where Cal/OSHA's limit is stricter than the federal PEL, the California value applies; OSHA's annotated PEL tables reproduce the Cal/OSHA values alongside the federal ones for comparison.

Monitoring

How Monitoring Demonstrates Compliance

Each limit is compared with exposure over its own period: the 8-hour TWA for the PEL, 15 minutes for the STEL, any moment for a ceiling. Continuous monitoring is what shows a STEL or ceiling being approached, which a shift-average sample cannot; personal sampling in the breathing zone documents individual exposure.

Recommended

best match
11 of 13 covered · 1 monitor · 1 gateway · 3 instruments

  1. Aethair PRO

    Industrial monitor for indoor and outdoor sites. Built-in sensors cover the essentials, and hot-swappable gas sensor cartridges and a differential-pressure option add more.

    Gas 1

    Aethair O₃+NO₂

    Nitrogen Dioxide (NO₂)Ozone (O₃)

    Four-electrode electrochemical sensing measures oxidizing gases (ozone plus nitrogen dioxide) and reports one…

    Gas 2

    Aethair CO (electrochemical)

    Carbon Monoxide (CO)

    An amperometric electrochemical CO cell with a solid, non-aqueous electrolyte (the long-life, low-power…

    Also fits: Aethair MultiGas+, Aethair CO (ppb, four-electrode)

    MultiSense

    Custom MultiSense built to order

    Carbon Dioxide (CO₂)Hydrogen Sulfide (H₂S)Sulfur Dioxide (SO₂)

    Built to order for the MultiSense socket with the Aethair CO₂ (dual NDIR) cartridge's sensor (0-5000 ppm, 1 ppm resolution), the Aethair H₂S cartridge's sensor (0-50 ppm, 5 ppb resolution), and the Aethair SO₂ cartridge's sensor (0-100 ppm, 5 ppb resolution).

    Expansion

    Free: differential pressure

    Also measures 13 more
    Dew PointHeat IndexRelative HumidityIlluminance / LightParticle Count (by size)PM1PM10PM2.5Total PM / Mass Conc.Barometric PressureEquivalent Continuous Level (Leq)Sound Pressure Level (SPL)Air Temperature

  2. Thiamis connects 3 instruments

    A gateway that connects the third-party instruments you choose to the Aethair Platform.

    • RAE Gas Detectors

      Chlorine (Cl₂)Ammonia (NH₃)Nitric Oxide (NO)

      RAE Systems (Honeywell) portable gas detectors.

      Models covering all of it: MultiRAE Lite, MultiRAE, MultiRAE Pro, MultiRAE Plus and 2 more · Connects over RS-232 (ASCII)

    • Defiant Technologies Specialty Air Analyzers

      BTEX / speciated VOC

      Defiant Technologies FROG portable gas chromatograph (GC-PID).

      Connects over USB (ASCII)

    • AMETEK Brookfield Specialty Air Analyzers

      Mercury (Hg)

      Jerome portable single-gas analyzers by AMETEK Brookfield (formerly AMETEK Arizona Instrument).

      Model with Mercury (Hg): Jerome-431X · Connects over RS-232 (ASCII)

    Also measures 4 more
    Methane (CH₄)Combustible (LEL)Oxygen (O₂)VOC (Total)

Not coveredHydrogen Chloride (HCl)Hydrogen Fluoride (HF)no supported configuration measures these yet

Customize this configuration

Who measures each parameter

Parameter Aethair PRO Aethair IAQ External
Carbon Monoxide (CO)CO (electrochemical), MultiGas+ +1 cartridges—3 instruments via Thiamis
Carbon Dioxide (CO₂)CO₂ (dual NDIR), CO₂ (self-calibrating NDIR) cartridgesBuilt in2 instruments via Thiamis
Hydrogen Sulfide (H₂S)H₂S cartridge—4 instruments via Thiamis
Sulfur Dioxide (SO₂)MultiSense, SO₂ cartridges—1 instrument via Thiamis
Nitric Oxide (NO)NO cartridge—1 instrument via Thiamis
Nitrogen Dioxide (NO₂)NO₂, MultiSense +1 cartridges—1 instrument via Thiamis
Ozone (O₃)O₃+NO₂ cartridge—1 instrument via Thiamis
Ammonia (NH₃)——1 instrument via Thiamis
Chlorine (Cl₂)——1 instrument via Thiamis
Mercury (Hg)——1 instrument via Thiamis
Hydrogen Chloride (HCl)HCl cartridge——
Hydrogen Fluoride (HF)HF cartridge——
BTEX / speciated VOC——1 instrument via Thiamis

Devices

Devices That Cover Cal/OSHA PEL

How much of this standard one Aethair monitor covers, followed by the third-party instruments in the sensor catalog that measure its parameters. Each connects to Environet through a Thiamis gateway, which adds whatever the monitor leaves out.

Aethair monitors

Aethair PRO Built in + Aethair O₃+NO₂, Aethair CO (electrochemical), Custom MultiSense (CO₂, H₂S, SO₂)6 of 13: CO, CO₂, H₂S, SO₂, NO₂, O₃

Covers part of it (combine on one Thiamis)

RAE Gas Detectors8 of 13: Cl₂, CO, CO₂, H₂S, NH₃, NO, NO₂, SO₂TSI GM460 Gas Detectors2 of 13: CO, H₂SRKI Instruments GX6000 Gas Detectors2 of 13: CO, H₂SAMETEK Brookfield Jerome Specialty Air Analyzers2 of 13: H₂S, MercuryDefiant Technologies FROG Specialty Air Analyzers1 of 13: BTEX / speciated VOCParticles Plus Particulate & Dust Monitors1 of 13: CO₂2B Technologies POM Specialty Air Analyzers1 of 13: O₃

Solutions

Solutions Judged Against Cal/OSHA PEL

Occupational Safety & Industrial Hygiene

Worker exposure, confined space, and heat stress

All solutions

Article Library

Articles on Cal/OSHA PEL

Ozone Exposure Limits and Monitoring: OSHA and NAAQS

OSHA's ozone PEL is 0.1 ppm as an 8-hour TWA. How NIOSH, ACGIH, and the 70 ppb NAAQS compare, and why ozone needs short-interval monitoring.

All articles

Questions

Cal/OSHA PEL FAQ

What is the Cal/OSHA PEL for carbon monoxide?

25 ppm as an 8-hour time-weighted average, with a ceiling of 200 ppm, stricter than the federal OSHA PEL of 50 ppm.

What does Cal/OSHA set for ozone?

A permissible exposure limit of 0.1 ppm as an 8-hour TWA and a short-term exposure limit of 0.3 ppm.

Which limit applies in California, federal or Cal/OSHA?

California employers follow Cal/OSHA's Table AC-1, which is stricter than the federal limits for many substances.

Monitor Against Cal/OSHA PEL

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