Passive Air Sampler

What is the Passive Air Sampler?

A small badge or tube that collects airborne gases and vapours by diffusion into a sorbent, without a pump. It is the right choice for long-term average exposure surveys and screening across many sites at low cost.

Overview

The passive sampler relies on the concentration gradient between ambient air and a sorbent, so molecules diffuse through a defined diffusion path or membrane and are retained. Activated charcoal, Tenax TA, silica gel and coated sorbents cover solvents, volatile organic compounds, formaldehyde, ammonia, ozone and sulfur dioxide. Uptake is proportional to concentration and exposure time through a sampling rate that is determined by the diffusion geometry; results are reported as time-weighted averages. Exposure ranges from a few hours to four weeks, and longer periods lower the detection limit but risk saturation and back-diffusion. After exposure, tubes and badges are sealed, kept cool and returned to the laboratory for solvent or thermal desorption and analysis. Because no pump or power is needed, dozens of units can be deployed simultaneously, making them useful for mapping spatial patterns and worker exposure.

How does it work?

Environmental sampling equipment captures a volume of the target medium under controlled conditions so that the laboratory result represents the site. Automatic water samplers use a peristaltic or vacuum pump to draw a fixed volume into bottles on a time or flow-proportional schedule, with pre-rinse cycles to limit cross-contamination and refrigeration or ice to preserve samples. Sediment grab samplers close spring-loaded jaws when lowered onto the bed, while core samplers drive a lined tube to recover an undisturbed vertical profile. Low-flow groundwater pumps use bladder or helical rotors to lift water at 0.1–0.5 L/min, reducing turbidity and volatilization. Passive air samplers rely on diffusion or permeation into a sorbent, integrating exposure over days to weeks. Containers, tubing and sorbents are chosen so analytes do not adsorb, leach or degrade before analysis.

What are the key features?

• No pump or power required, so many units deploy simultaneously.
• Badge-and-tube formats cover VOCs, formaldehyde, ammonia and ozone.
• Sampling rates from the diffusion geometry give time-weighted averages.
• Sealed transport caps prevent loss between field and laboratory.
• Low unit cost supports wide spatial screening networks.
• Exposure from several hours to four weeks matches survey objectives.

What are the technical specifications?

A typical passive air sampler configuration offers sampler format of Badge or sorbent tube, sorbent media of Activated charcoal, Tenax TA, silica gel, target compounds of VOCs, formaldehyde, ammonia, ozone, SO2, exposure duration of 8 hours to 28 days, sampling rate of 0.5–50 mL/min (analyte dependent) and detection limit of Low µg/m³ for 7-day exposure. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The Passive Air Sampler is used in indoor and workplace air exposure surveys, ambient VOC screening networks, fence-line odour and solvent monitoring and long-term trend studies at background sites. Across the wider Environmental Sampling class, laboratories also deploy it for contaminated site investigation, surface water and effluent monitoring and groundwater compliance monitoring.

Which standards and certifications apply?

Relevant standards and methods include ISO 5667-1, ISO 5667-3, ISO 18400-101, ASTM D6907, US EPA Method 1669 and EN ISO 16017-1. Certification candidates for this model are CE, RoHS and ISO 9001 manufacturing; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Plan a sampling and analysis plan that defines locations, depths, frequencies, preservation and chain-of-custody. Clean and decontaminate reusable equipment between stations using procedures free of the target analytes, and collect field blanks, trip blanks and duplicates. Transport samples in coolers with ice at 0–4 °C and ship within the method holding time. Calibrate pumps and flow meters before each campaign and record volumes for flow-proportional composites. For regulatory work, follow the applicable guidance and keep records for audit. Store tubing and bottles away from solvents and exhaust, and replace worn seals and liners, which are common sources of contamination and leakage.

How do I select the right Passive Air Sampler?

Select passive samplers for time-weighted average concentrations over long periods and for screening many locations cheaply. When short-term peaks, real-time alarms or compound identification are needed, an active sampler or portable gas analyzer is required. In an RFQ, state target compounds, required detection limit, exposure duration, sorbent and analysis method.

How does it compare with other Environmental Sampling variants?

Start from the matrix and the analytical method, because these decide the container, preservation and allowable holding time. For flowing water and effluent, choose between grab samples and automatic samplers that can composite over time or flow. For sediments and soils, decide whether a surface grab or an undisturbed core is required, and match the sampler material to the target analytes so metals do not leach from brass or alloy components. For groundwater, low-flow sampling gives lower turbidity and more reproducible metals results than bailers. For air, select active sorbent tubes when short-term concentrations are needed and passive samplers when long-term averages are sufficient. Confirm decontamination procedures, blank requirements and the number of duplicates before specifying.