BTEX Testing Lab Houston TX — Benzene, Toluene, Ethylbenzene & Xylenes

AIHA LAP accredited (LAP-101470) BTEX testing lab serving Houston and the Gulf Coast. Personal BTEX testing by NIOSH 1501 GC-FID for OSHA benzene compliance under 29 CFR 1910.1028, NIOSH 1500 total hydrocarbon analysis from the same charcoal tube, and EPA Method 325B refinery fenceline benzene analysis. Every BTEX testing sample is analysed in-house at our Houston TX industrial hygiene laboratory — no subcontracting, no send-outs.

ISO/IEC 17025 Accredited AIHA LAP · ID: LAP-101470 NIOSH 1501 · 1500 · EPA 325B Benzene OSHA Compliance
Get a Quote
What's onthis pageQuick links to page sections
What Is BTEX TestingMethod explained
Benzene LimitsOSHA · ACGIH · NIOSH
All Four BTEX PELsB · T · E · X compared
BTEX MethodsNIOSH 1501 · EPA 325B
Total HydrocarbonsNIOSH 1500
Choosing a LabBTEX testing lab criteria
TAT & KitsRush options
Who We ServeIndustries
FAQAnswers
Lab AccreditationISO/IEC 17025:2017
IH Lab AccreditationAIHA LAP · ID: LAP-101470
Accredited BTEX MethodsNIOSH 1501 · OSHA 1005 · EPA 325B
BTEX Testing LabHouston, TX · In-House Analysis
Why BTEX Testing Matters

Benzene has no safe exposure level — OSHA's action level is 0.5 ppm, and petrochemical operations routinely exceed it without active monitoring

Benzene Is an IARC Group 1 Carcinogen

Benzene is a confirmed human carcinogen — the highest IARC classification — and is directly linked to acute myeloid leukemia (AML) and other blood cancers. OSHA's Benzene Standard (29 CFR 1910.1028) requires documented BTEX testing any time exposures may exceed the 0.5 ppm action level. There is no recognized safe threshold.

OSHA Enforcement Is Active in Petrochemical

Benzene and BTEX violations are among the most frequently cited in refinery, chemical plant, and petroleum handling inspections across Texas. Without documented personal exposure records from an accredited BTEX testing lab, any OSHA inspection following a health incident creates immediate citation risk. Monitoring records from an AIHA LAP accredited laboratory are your legal shield.

Toluene and Xylenes Are Not Harmless By-Products

Benzene attracts the attention, but toluene, ethylbenzene and xylenes are central nervous system depressants with their own PELs — and ACGIH sets toluene and ethylbenzene TLVs ten and five times lower than the OSHA figure. Speciated BTEX testing quantifies all four separately so no compound is assessed against the wrong limit.

Total Hydrocarbon Readings Conceal Benzene

A direct-reading meter or a total hydrocarbon result that sits comfortably under the 500 ppm Stoddard solvent PEL tells you nothing about benzene, which typically makes up 1–5% of petroleum distillate vapour. At 300 ppm total, that is potentially 3–15 ppm benzene — many times the PEL. Only speciated BTEX testing resolves it.

Occupational Air Monitoring

What Is BTEX Testing?

BTEX testing is targeted air monitoring for four aromatic hydrocarbons — benzene, toluene, ethylbenzene and xylenes — in workplace air. A calibrated personal pump draws air through an activated charcoal tube clipped in the worker's breathing zone across a full shift. At the laboratory the tube is desorbed with carbon disulfide and each compound is quantified individually by GC-FID under NIOSH Method 1501.

The word that matters is individually. BTEX testing reports benzene as its own number rather than folding it into a total hydrocarbon sum — which is precisely what OSHA 29 CFR 1910.1028 requires, because benzene's action level of 0.5 ppm sits hundreds of times below the PEL for the petroleum distillate mixtures it is usually found in.

  • NIOSH 1501 GC-FID — the method OSHA expects for benzene records
  • Personal 8-hour TWA and 15-minute STEL sampling supported
  • All four BTEX compounds quantified from a single charcoal tube
  • Results compared to OSHA PEL, ACGIH TLV and NIOSH REL
  • Analysed in-house at our AIHA LAP accredited Houston BTEX testing lab
Activated charcoal sorbent tube used for NIOSH 1501 BTEX testing at AGT Labs Houston TX
Occupational Compliance

BTEX Testing — Benzene, Toluene, Ethylbenzene & Xylenes

Targeted personal exposure monitoring by NIOSH 1501 charcoal tube, run in-house at our AIHA LAP accredited BTEX testing lab to document OSHA PEL compliance in petrochemical and refining operations.

Benzene — The Critical Compound

OSHA PEL, Action Level, ACGIH TLV & NIOSH REL — All Compared

Benzene is the reason BTEX testing programs exist. Its regulatory limits are among the most stringent for any common workplace chemical — and they differ significantly between OSHA, ACGIH, and NIOSH. AGT Labs reports against all three.

Why Benzene Dominates BTEX Testing Programs

Benzene is present in virtually every petroleum product, from crude oil and gasoline to refinery process streams and aromatic solvents. Unlike toluene and xylenes — which are irritants and CNS depressants — benzene is a bone marrow toxin and confirmed human carcinogen that causes acute myeloid leukemia (AML) and aplastic anemia at long-term exposures below 1 ppm. The NIOSH REL of 0.1 ppm reflects this carcinogenicity — it is 10 times more protective than OSHA's PEL. AGT Labs uses NIOSH 1501 GC-FID BTEX testing for routine benzene compliance monitoring, with detection limits well below the OSHA action level, ensuring all exceedances are captured and reported with full confidence.

OSHA PEL
29 CFR 1910.1028 · 8-hr TWA
1 ppm
Hard Limit
OSHA Action Level
Triggers monitoring + medical surveillance
0.5 ppm
Enhanced Monitoring
OSHA STEL
15-minute short-term exposure limit
5 ppm
STEL
ACGIH TLV
More protective than OSHA PEL
0.5 ppm
Best Practice
NIOSH REL
Carcinogen — lowest feasible concentration
0.1 ppm
Carcinogen REL
IARC Classification
Confirmed human carcinogen (AML)
Group 1
Carcinogen
All Four Compounds

BTEX Exposure Limits — Benzene, Toluene, Ethylbenzene & Xylenes

Speciated BTEX testing exists because these four compounds carry wildly different limits. Assessing them as a group, or against a single mixture PEL, means at least one compound is being judged against the wrong number.

BTEX Compound OSHA PEL (8-hr TWA) OSHA STEL / Ceiling ACGIH TLV NIOSH REL Primary Health Concern
Benzene 1 ppm · AL 0.5 ppm 5 ppm STEL 0.5 ppm 0.1 ppm IARC Group 1 carcinogen — AML, aplastic anemia
Toluene 200 ppm 300 ppm ceiling 20 ppm 100 ppm CNS depression, developmental toxicity
Ethylbenzene 100 ppm — 20 ppm 100 ppm IARC Group 2B, ototoxicity, irritation
Xylenes (o/m/p) 100 ppm — 100 ppm 100 ppm CNS depression, eye and respiratory irritation

Reference values only. Verify current OSHA, ACGIH and NIOSH values against the governing standard for your jurisdiction and application. Note the gap between the OSHA PEL and ACGIH TLV for toluene (10×) and ethylbenzene (5×) — every AGT Labs BTEX testing report carries all three comparisons.

BTEX Testing Methods

BTEX Testing Lab Methods — NIOSH 1501 & EPA 325B

NIOSH 1501 — BTEX Testing by GC-FID

The occupational standard for personal 8-hour TWA BTEX testing — the method OSHA expects for benzene PEL documentation. Uses activated charcoal tubes with a personal sampling pump, adsorbing aromatic hydrocarbons during a full work shift, then desorbing with CS₂ for GC-FID analysis.

Analytes:Benzene, Toluene, Ethylbenzene, Xylenes (BTEX)
Media:Activated charcoal tube (100/50 mg)
Best for:Personal 8-hr TWA compliance (OSHA 1910.1028)

EPA Method 325B — Fenceline Benzene Analysis

EPA's Refinery Sector Rule (40 CFR Part 63 Subpart CC) requires continuous fenceline benzene monitoring using passive sorbent tubes deployed for two-week integrated sampling periods along facility perimeters. AGT Labs supports these programs with passive tube supply, analysis, and result reporting.

Standard:EPA Method 325B (analysis) · 325A passive sampling
Media:Passive sorbent tube (thermal desorption)
Best for:Petroleum refinery perimeter monitoring
Field Protocol Reference

BTEX Testing Field Protocol — NIOSH 1501 Charcoal Tube

Tube setup
100/50 mg activated charcoal tube. Open immediately before sampling — charcoal begins adsorbing background VOCs on contact with air. Do not open tubes in the laboratory or any solvent-contaminated environment.
Flow rate
50–200 mL/min personal sampling. Do not exceed 200 mL/min — breakthrough occurs at high flow rates for lower molecular weight aromatics including benzene. Calibrate pump with tube in-line before and after sampling.
Duration
Full 8-hour shift for TWA. Short-term sampling (15 min) for STEL assessment requires higher flow rate with same tube. Both can be conducted simultaneously with a second charcoal tube and dedicated pump.
Field blanks
Minimum 10% of sample count. Break the seal on an unused tube at the sampling location for 30 seconds, re-cap immediately, and label it clearly as a field blank on the chain of custody.
Hold time
Refrigerate (4°C) immediately after sampling. Analyze within 14 days. Ship with cold packs. Benzene is volatile — warm storage degrades sample integrity and produces falsely low results.
Petroleum Distillate Monitoring

Total Hydrocarbons Monitoring — NIOSH 1500

Aggregate aliphatic and aromatic hydrocarbon monitoring for Stoddard solvent, mineral spirits, naphtha, and petroleum distillate workplaces — GC-FID analysis from the same charcoal tube as BTEX testing. Total hydrocarbon results do not replace compound-specific BTEX testing where benzene may be present.

NIOSH 1500 — Total Hydrocarbon Method

What Is Total Hydrocarbon Monitoring and When Is It Required?

Total hydrocarbon (THC) monitoring measures the combined mass concentration of all aliphatic and aromatic hydrocarbons present in breathing-zone air as a single aggregate value — without identifying each individual compound. It applies when the OSHA PEL is set for the total petroleum distillate mixture rather than individual compounds.

Aggregate vs Speciated

NIOSH 1500 Reports a Sum — BTEX Testing by NIOSH 1501 Reports Each Compound

NIOSH 1500 uses a non-polar GC column and GC-FID detection to report all captured hydrocarbons as a single sum in ppm or mg/m³. This is the correct approach when the regulatory PEL applies to the total mixture — Stoddard solvent (500 ppm), VM&P naphtha, mineral spirits, or kerosene — and the individual compound profile is not needed for compliance.

Both NIOSH 1500 and NIOSH 1501 BTEX testing use the same 100/50 mg activated charcoal tube collected at the same flow rate. Both can be run from the same field sample — the laboratory splits the CS₂ extract for both analyses. One tube collection, two compliance results.

  • Same charcoal tube as NIOSH 1501 BTEX testing — no second tube required
  • GC-FID with non-polar column — all carbons summed as one value
  • Result compared to Stoddard solvent PEL of 500 ppm TWA
  • Applicable to mineral spirits, VM&P naphtha, kerosene, and petroleum distillates
  • Always order alongside NIOSH 1501 BTEX testing in any petroleum product environment
NIOSH 1500 — Method Specifications
Method
NIOSH 1500 — Hydrocarbons (GC-FID, non-polar column)
Analytes
Total aliphatic + aromatic hydrocarbons — single sum result in ppm or mg/m³
Collection media
100/50 mg activated charcoal tube — same tube as NIOSH 1501
Flow rate
0.01–0.2 L/min (10–200 mL/min)
Desorption
Carbon disulfide (CS₂) — same as NIOSH 1501; both methods from one extract
OSHA PEL
Stoddard solvent 500 ppm (8-hr TWA) · Mineral spirits 100 ppm · Substance-specific PELs for identified components
NIOSH REL
350 mg/m³ (Stoddard solvent) · Lowest feasible for individual aromatic components
Hold time
Refrigerate at 4°C · Analyse within 14 days of collection
Best for
Stoddard solvent, VM&P naphtha, mineral spirits, kerosene, petroleum distillate PEL compliance
Limitation
Cannot quantify benzene separately — never rely on NIOSH 1500 alone in aromatic environments
OSHA PEL Reference

Total Hydrocarbon OSHA PELs — Petroleum Distillates

Petroleum Distillate OSHA PEL (8-hr TWA) NIOSH REL NIOSH Method Key Industries
Stoddard Solvent 500 ppm (2,900 mg/m³) 350 mg/m³ NIOSH 1500 Dry cleaning, degreasing, printing
Mineral Spirits 100 ppm 350 mg/m³ NIOSH 1500 Painting, surface prep, cleaning
VM&P Naphtha 300 ppm (1,350 mg/m³) Not established NIOSH 1500 Coatings, adhesives, rubber
Kerosene / Jet Fuel No OSHA PEL (use ACGIH TLV 200 mg/m³) Not established NIOSH 1500 Aviation, fuel handling, heating
n-Hexane (individual) 500 ppm 50 ppm (neurotoxin) NIOSH 1500 / 1501 Adhesives, shoe manufacturing, lab
Benzene (in petroleum distillate) 1 ppm PEL · 0.5 ppm AL 0.1 ppm (carcinogen) NIOSH 1501 BTEX testing — mandatory All petroleum product environments
Critical — Total Hydrocarbons Never Confirms Benzene Is Safe

A total hydrocarbon result below the 500 ppm Stoddard solvent PEL does not mean benzene is below its 0.5 ppm action level. Benzene typically represents 1–5% of total petroleum distillate vapour. At a total THC reading of 300 ppm, that could mean 3–15 ppm benzene — three to fifteen times the OSHA PEL. NIOSH 1501 speciated BTEX testing is mandatory in any petroleum product environment, regardless of how low the total hydrocarbon reading appears. Order both methods from the same charcoal tube.

Method Selection

NIOSH 1500 vs NIOSH 1501 BTEX Testing — When to Order Each

Both methods use the same charcoal tube — the decision is made at the COC stage, not the field stage. In petroleum product environments, both should always be specified together.

Order NIOSH 1500 (Total Hydrocarbons) When
Product type
Stoddard solvent, mineral spirits, VM&P naphtha, kerosene, petroleum distillates — where total mixture PEL applies
Compliance goal
Confirming total hydrocarbon burden is below Stoddard solvent OSHA PEL of 500 ppm
Industries
Dry cleaning, parts degreasing, paint mixing rooms, mechanical workshops using petroleum distillate cleaners
Always pair with
NIOSH 1501 BTEX testing — to confirm benzene is below its separate 0.5 ppm action level from the same tube
Order NIOSH 1501 (Speciated BTEX Testing) When
Product type
Any petroleum product, aromatic solvent, fuel, paint, coating, or cleaning product that contains or may contain benzene
Compliance goal
OSHA 1910.1028 benzene action level (0.5 ppm) and PEL (1 ppm) compliance — individual compound PELs for T, EB, and Xylene
Industries
Petroleum refining, petrochemical manufacturing, fuel handling, painting, printing, rubber, shoe manufacturing
Always pair with
NIOSH 1500 when the environment also uses complex petroleum distillate mixtures requiring total mixture PEL comparison
500 ppm
Stoddard solvent OSHA PEL
1 tube
NIOSH 1500 + BTEX testing from same charcoal tube
0.5 ppm
Benzene action level — always verify with BTEX testing
Selecting a Laboratory

How to Choose a BTEX Testing Lab for OSHA Compliance

Not every laboratory that offers BTEX testing holds accreditation for the specific method your project requires. Four checks before you ship samples.

1 · Verify the Accreditation Scope
Check
Confirm the BTEX testing lab holds AIHA LAP accreditation under the Industrial Hygiene Laboratory Accreditation Program (IHLAP), and that NIOSH 1501 appears on its published scope. General ISO/IEC 17025 accreditation does not automatically cover the method you need — scopes are narrower than most buyers assume.
AGT Labs
AIHA LAP-101470 (IHLAP) lists NIOSH 1501 / 1501 Mod for BTEX and aromatic hydrocarbons, NIOSH 1500 for total hydrocarbons, OSHA 1005 for benzene, OSHA 1002 for xylenes, OSHA 111 and OSHA 4000 for toluene, and EPA 325B for fenceline benzene — all publicly verifiable.
2 · Check the Reporting Limit
Check
The reporting limit must sit well below the 0.5 ppm benzene action level — not merely below the 1 ppm PEL. A result reported as "less than 0.6 ppm" cannot demonstrate you are under the action level, and leaves the monitoring obligation unresolved.
AGT Labs
NIOSH 1501 GC-FID BTEX testing resolves benzene well below the action level on a standard full-shift sample volume.
3 · Confirm Analysis Is In-House
Check
Ask whether BTEX testing is run on the laboratory's own instruments. A subcontracted result carries the subcontractor's accreditation and adds transit days to your turnaround — and the chain of custody grows a link you did not choose.
AGT Labs
All GC-FID analysis performed in-house at 10200 East Freeway, Houston TX. No subcontracting, no send-outs.
4 · Review a Sample Report
Check
The report should compare each result to OSHA PEL, ACGIH TLV and NIOSH REL. A report showing only the OSHA figure understates risk — benzene's ACGIH TLV is half the PEL and the NIOSH REL is one tenth of it.
AGT Labs
Every BTEX testing report carries tri-limit comparison, method reference, analyst signature, QA sign-off, and AIHA LAP-101470 accreditation. Request a sample report.

Need broad VOC screening rather than BTEX compliance?

BTEX testing answers a specific occupational question: how much benzene, toluene, ethylbenzene and xylene did this worker breathe. When you don't yet know which compounds are present — vapour intrusion, indoor air quality, ambient monitoring, unidentified odour complaints — a whole-air SUMMA canister analysed by GC-MS is the right tool, covering a broad VOC list in a single run. That work lives on a separate page.

VOC Testing & EPA TO-15
Sampling Decision Guide

When BTEX Testing Is the Required Method

Three scenarios where speciated BTEX testing — not a total hydrocarbon sum and not a direct-reading meter — is what the regulation expects.

Refinery / Petrochemical Benzene Compliance

Workers in petroleum refining, chemical production, and fuel transfer operations are commonly exposed to benzene above the OSHA action level of 0.5 ppm. OSHA's Benzene Standard requires documented personal monitoring, medical surveillance, and records retention.

→ Use NIOSH 1501 BTEX testing (charcoal tube) · 8-hr TWA

Solvent Degreasing & Surface Coating Operations

Industrial cleaning and coating operations generate toluene, xylenes and other aromatic solvents that require personal exposure monitoring against compound-specific OSHA PELs — and frequently contain benzene as a trace constituent of the base petroleum distillate.

→ Use NIOSH 1501 BTEX testing + NIOSH 1500 total hydrocarbons

EPA Fenceline Monitoring — Refineries

EPA's Refinery Sector Rule (40 CFR 63 Subpart CC amendments) requires fenceline benzene monitoring using passive sorbent tubes deployed at facility perimeters for two-week integrated sampling periods. Triggers corrective action at ≥9 µg/m³ annual average.

→ Use EPA Method 325B analysis (325A passive tube sampling)
Lab Logistics

BTEX Testing Turnaround & Sampling Media

BTEX Testing Isn't One-and-Done

OSHA 1910.1028 requires repeat monitoring at least every 6 months once exposures reach the 0.5 ppm action level, and refinery fenceline programs (EPA 325B) run on continuous two-week cycles. Set up a recurring program and we'll schedule your rounds, supply charcoal tubes and pumps, and apply standing-account volume pricing.

Set Up a Monitoring Program
Turnaround — BTEX Testing (NIOSH 1501)
1-Day Rush1 business day+100%
2-Day Rush2 business days+75%
3-Day Rush3 business days+50%
4-Day Rush4 business days+25%
Standard5+ business daysNo Surcharge
Samples received before 2:00 PM CST logged same day. Charcoal tubes for BTEX testing must be refrigerated after collection and analysed within 14 days. Call (713) 453-6090 for rush confirmations.

BTEX Testing Sampling Kits

  • Lot-certified activated charcoal tubes (100/50 mg) for NIOSH 1501 BTEX testing
  • Calibrated low-flow personal pumps (50–200 mL/min) — loaner program
  • Field blank charcoal tubes (10% QA compliance)
  • Passive sorbent tubes for EPA Method 325A fenceline deployment
  • Tenax TA / Carbopack thermal desorption tubes
  • Passive OVM diffusion badges (3M 3500 series) for screening
  • Industrial Hygiene Chain of Custody (COC) with pre-coded analytes
  • Pre-paid UPS return shipping label with cold pack packaging
Download IH COC Form
Industries & Clients

Who Relies on Our BTEX Testing Lab

Petroleum Refining & Petrochemical Manufacturing

The Houston Ship Channel complex houses one of the world's largest concentrations of petroleum and chemical facilities. Routine BTEX testing (NIOSH 1501) for OSHA 1910.1028 compliance, turnaround and unit shutdown work, and maintenance operations in benzene-rich process environments.

Oil & Gas Operations

Upstream oil and gas — worker personal BTEX testing at well pads, tank batteries, produced water handling facilities, and compression stations, where benzene exposure during gauging and manual tank operations routinely exceeds the action level.

Fuel Terminals, Tank Cleaning & Marine Transfer

Tank gauging, confined space entry for tank cleaning, loading rack operations, and marine product transfer generate short, intense benzene exposures that a full-shift average can dilute. Both TWA and 15-minute STEL BTEX testing are typically required.

Industrial Coating, Printing & Cleaning

Solvent-based coatings, printing inks, and parts-cleaning operations generate toluene and xylene vapours requiring personal exposure monitoring against compound-specific PELs. NIOSH 1501 BTEX testing paired with NIOSH 1500 total hydrocarbons from a single charcoal tube.

Rubber, Adhesives & Foundry Operations

Rubber compounding, adhesive application, shoe manufacturing, and foundry core-making use aromatic and petroleum distillate solvents with a long history of benzene content. Speciated BTEX testing separates benzene from the bulk solvent for accurate PEL comparison.

IH Consultants & EH&S Compliance Programs

Industrial hygiene consulting firms managing multi-site BTEX testing programmes across refineries, chemical plants, and mixed industrial facilities. AGT Labs provides AIHA LAP accredited, OSHA-defensible NIOSH 1501 data with tri-limit reporting (OSHA/ACGIH/NIOSH) and a dedicated project coordinator.

Client Support

BTEX Testing — Frequently Asked Questions

What is BTEX testing?
BTEX testing is targeted air monitoring for four aromatic hydrocarbons — benzene, toluene, ethylbenzene and xylenes — in workplace air. Air is drawn through an activated charcoal tube by a personal pump worn in the worker's breathing zone, the tube is desorbed with carbon disulfide at the laboratory, and each compound is quantified individually by GC-FID under NIOSH Method 1501. BTEX testing is the method OSHA expects for benzene compliance under 29 CFR 1910.1028, because it reports benzene separately rather than as part of a total hydrocarbon sum. All BTEX testing at AGT Labs runs in-house at our AIHA LAP accredited (LAP-101470) Houston BTEX testing lab, with every result compared to OSHA PEL, ACGIH TLV and NIOSH REL.
How do I choose a BTEX testing lab for OSHA compliance?
Verify four things before sending samples to any BTEX testing lab. First, confirm the laboratory holds AIHA LAP accreditation under IHLAP and that NIOSH 1501 sits on its published scope — general ISO/IEC 17025 accreditation does not automatically cover the method you need. Second, confirm the reporting limit is well below the 0.5 ppm benzene action level, not just below the 1 ppm PEL. Third, confirm analysis is performed in-house rather than subcontracted, since a subcontracted result carries the subcontractor's accreditation. Fourth, confirm the report compares results to OSHA PEL, ACGIH TLV and NIOSH REL — a report showing only the OSHA figure understates the risk. AGT Labs meets all four criteria under AIHA LAP-101470.
What is the OSHA PEL for benzene in air?
OSHA's PEL for benzene is 1 ppm (8-hour TWA) and STEL is 5 ppm (15-minute) under 29 CFR 1910.1028. The action level is 0.5 ppm — exceeding this triggers enhanced monitoring (every 6 months), medical surveillance, and exposure notification. ACGIH TLV is 0.5 ppm. NIOSH REL is 0.1 ppm (carcinogen). AGT Labs reports all three limits in every BTEX testing compliance report so clients have the complete regulatory picture, not just the OSHA minimum.
What are the exposure limits for toluene, ethylbenzene and xylenes?
The three non-benzene BTEX compounds carry far higher OSHA PELs than benzene, but ACGIH sets significantly more protective values for two of them. Toluene: OSHA PEL 200 ppm 8-hr TWA with a 300 ppm ceiling, ACGIH TLV 20 ppm, NIOSH REL 100 ppm. Ethylbenzene: OSHA PEL 100 ppm, ACGIH TLV 20 ppm, NIOSH REL 100 ppm. Xylenes (o/m/p): OSHA PEL 100 ppm, ACGIH TLV 100 ppm with a 150 ppm STEL, NIOSH REL 100 ppm. The gap between OSHA and ACGIH is a factor of ten for toluene and five for ethylbenzene — which is why every AGT Labs BTEX testing report compares each compound against all three limits. Always verify current values against the governing standard for your jurisdiction.
What is the difference between NIOSH 1501 and NIOSH 1500?
Both use the same 100/50 mg charcoal tube at the same flow rate, and both can be run from one field sample because the lab splits the CS₂ extract. NIOSH 1501 is speciated BTEX testing — benzene, toluene, ethylbenzene and xylenes reported as individual concentrations, which is what OSHA 1910.1028 requires. NIOSH 1500 reports all aliphatic and aromatic hydrocarbons as one aggregate sum, applicable when the PEL is set for a total petroleum distillate mixture such as Stoddard solvent at 500 ppm. A total hydrocarbon result under the mixture PEL never confirms benzene is under its 0.5 ppm action level — always order NIOSH 1501 BTEX testing alongside it.
When do I need BTEX testing rather than general VOC testing?
Order BTEX testing (NIOSH 1501 or OSHA 1005) when you need personal 8-hour TWA compliance data for the OSHA benzene standard — petroleum handling, fuelling, chemical manufacturing, refinery work, tank cleaning — or when workers are exposed specifically to petroleum-based aromatic solvents. Order broad screening instead when the identity of the compounds is unknown, or the application is indoor air quality, vapour intrusion or ambient monitoring; see our VOC testing and EPA TO-15 page. In petrochemical environments the two are frequently ordered together — broad screening characterises the source, BTEX testing documents each worker's compliance exposure.
Does AGT Labs provide charcoal tubes and personal sampling pumps for BTEX testing?
Yes. AGT Labs supplies lot-certified activated charcoal tubes (100/50 mg) for NIOSH 1501 BTEX testing, field blank tubes for QA compliance, Tenax TA and Carbopack thermal desorption tubes, and passive OVM diffusion badges for screening. Calibrated low-flow personal air sampling pumps (50–200 mL/min) are available on a loaner programme. Every kit ships with an Industrial Hygiene Chain of Custody carrying pre-coded analytes and a pre-paid UPS return label. Call (713) 453-6090 to arrange kit supply.
How long are charcoal tube BTEX samples valid after collection?
Charcoal tubes collected for NIOSH 1501 BTEX testing should be refrigerated at 4°C immediately after sampling and analysed within 14 days. Ship with cold packs. Benzene is highly volatile and warm storage degrades sample integrity, producing falsely low results that can mask an action level exceedance. Cap both ends of the tube immediately after sampling, record exact start and stop times and calibrated flow rate on the COC, and note the requested turnaround. AGT Labs flags any sample approaching its hold time limit during log-in.
Can you test for benzene at refineries for EPA fenceline monitoring?
Yes. EPA's Refinery Sector Rule (40 CFR Part 63 Subpart CC) requires benzene fenceline monitoring using passive sorbent tubes collected under EPA Method 325A and analysed by the accredited EPA Method 325B, deployed for two-week integrated periods along the facility perimeter. The action level is a 9 µg/m³ annual average. AGT Labs supports these programmes with passive tube supply, Method 325B analysis, and result reporting in the required format. For upstream oil and gas, well pad and produced water assessments use NIOSH 1501 BTEX testing for personal monitoring. Call (713) 453-6090.
Is AGT Labs accredited for BTEX testing?
Yes. AGT Labs holds AIHA LAP accreditation (ID: LAP-101470) under the Industrial Hygiene Laboratory Accreditation Program (IHLAP) covering GC-FID methods including NIOSH 1501 for BTEX testing, NIOSH 1500 for total hydrocarbons, and additional GC-FID methods for aromatic and aliphatic hydrocarbons. The same scope covers OSHA 1005 (benzene), OSHA 1002 (xylenes), OSHA 111 and OSHA 4000 (toluene), and EPA 325B by GC/MS for refinery fenceline benzene — 117 method entries in total across 12 analytical platforms. Verify at aihaaccreditedlabs.org or see our accreditations page for the published scope. All BTEX testing is performed in-house at 10200 East Freeway, Houston under ISO/IEC 17025:2017 — no subcontracting, no send-outs.

Need an Accredited BTEX Testing Lab?

AIHA LAP Accredited (LAP-101470) · ISO/IEC 17025 · NIOSH 1501 BTEX testing · NIOSH 1500 total hydrocarbons · EPA Method 325B fenceline benzene · GC-FID in-house · OSHA 1910.1028 compliance · Houston TX. Ask about recurring monitoring programs and volume pricing for ongoing benzene compliance sampling.

Get a Quote Call (713) 453-6090
Get a Quote
Get a Quote