By Bill Allgeier, Laboratory Manager, ALS USA Environmental

When it comes to monitoring Volatile Organic Compounds (VOCs) at brownfield sites, especially those in remote or power-limited locations, passive air sampling offers an accessible, reliable option. Unlike active sampling—which requires power sources and calibrated pumps—passive techniques rely on diffusion to collect samples over time. 

These low-maintenance approaches are growing in popularity across site remediation, health and safety, and fenceline monitoring projects. This article covers the different passive VOC sampling tools available, their strengths, and how to choose the right one for your site.

Cost Effective, Field-Friendly

Passive air sampling collects airborne contaminants without pumps or powered devices. Instead, compounds are captured as they naturally diffuse through the air and into the sampling media. It’s a cost-effective and field-friendly method, ideal for long-duration monitoring or projects where access is limited. Common applications include indoor air testing, ambient outdoor air, personal exposure monitoring, and soil vapor investigations.

Passive VOC Sampling Tools

There are four key passive sampling options for VOCs. Each tool fits different field conditions, project goals, and regulatory contexts.

• Silonite Canisters are ideal for “whole air” sampling. The canisters are filled over 24 hours using a flow regulator – they require no pump and allow for analysis of 60+ VOCs. Additional methods like reduced sulfur compounds and fixed gases can be analyzed from the same canister, removing the need to deploy multiple sampling techniques. They're highly versatile and suitable for indoor, outdoor, and soil vapor applications.
• Passive TD Tubes are used for long-term sampling (up to 14 days, depending on the compound), especially for low-level VOC monitoring. They're small, rugged, and comply with EPA Method 325. Great for fenceline, LDAR, and indoor use. However, typically they have a limited number of analytes that can be reported. 
• VOC Badges are the go-to option for personal exposure monitoring. Workers wear the badge for up to 8 hours to assess individual VOC exposure levels. These are compliant with occupational health standards.
• Radiello Samplers are flexible samplers with a 7-day deployment window, ideal for industrial or mining sites. They measure up to 31 VOCs and can also support non-VOC testing (e.g., formaldehyde, NO2).

Need to ship your samples fast? Canisters and TD tubes don’t require refrigeration and ship easily with commercial couriers.

Choosing the Right Tool for the Job

Selecting the best method depends on your project objectives, site conditions, and regulatory requirements. Consider:

• •Sampling duration – Canisters (any duration up to 7 days), TD tubes (up to 14 days, depending on the compound), badges (8 hours), and Radiello (7 days).
• Target VOCs – Do you need a wide panel (e.g., over 60 compounds)? Go with canisters. Need a focused list? Badges or TD tubes may suffice.
• Sampling environment – For personal exposure, use VOC badges. For soil vapor, ambient air or industrial zones, canisters or TD tubes work better.
• Accreditation needs – For example, ALS provides NELAP & AIHA accreditation for methods using canisters and TD tubes, ensuring data meets defensibility standards.

Why Passive Sampling Works Well for Brownfield Sites

Passive sampling is often the best fit for brownfield redevelopment projects because it’s simple, scalable, and doesn’t require power or bulky equipment. It can support key project stages, including baseline air quality assessments, post-remediation verification, and long-term monitoring. And since these methods are non-intrusive, they’re ideal in community-sensitive areas.

Whether you’re assessing indoor air, monitoring an industrial fenceline, or verifying cleanup at a brownfield site, passive VOC sampling is a proven and practical approach that ensures your sampling campaign is efficient, accurate, and compliant.

The Author:

Bill Allgeier is Laboratory Manager of the ALS USA Environmental full-service laboratory in Rochester, NY.  Bill has been with the ALS environmental team for 26 years as an Analyst, Operations Manager and Lab Manager, and oversees a 24,000 sq ft. facility where the team processes over 290,000 air, soil, water, drinking water and waste sample tests annually.   Email: bill.allgeier@alsgobal.com