Fenceline Monitoring for Petroleum Refineries: Comparing Passive and Real-Time Options

Fenceline monitoring for petroleum refineries a regulatory obligation at certain facilities. Section 63.658 of the National Emission Standards for Hazardous Air Pollutants (NESHAP) requires refineries to track benzene concentrations at their site boundaries. The baseline method outlined in the regulation is passive air sampling method. However, there’s a lesser-known but fully compliant alternative: real-time air monitoring. That’s exactly where AirLogics comes in—with a monitoring system designed to meet the rule without delay or guesswork.

What the Rule Requires: Passive Sampling is the Starting Point?

According to the EPA rule, refineries must monitor benzene levels using a method that reflects concentration at the site boundary over time. The default method is passive sampling. This involves deploying sorbent tubes around the fenceline and collecting samples over a 14-day period. The tubes are then sent to a lab for analysis, and results can take several days to process.

This satisfies the rule’s minimum requirement. But it’s a slow, inflexible system that can’t detect spikes in emissions until it’s too late. If benzene concentrations breach the threshold, refineries are required to investigate and mitigate. With passive sampling, this means reacting to old data.

What’s Also Allowed: Real-Time Monitoring as a Regulatory Alternative?

While passive sampling is the default, 40 CFR §63.658(k)(6) clearly permits an alternative: real-time monitoring systems that meet the intent of the rule. These systems must provide data that allows facilities to track benzene levels consistently and take corrective action when limits are approached.

AirLogics delivers exactly this. We don’t offer passive sampling. We provide real-time fenceline air monitoring that meets regulatory expectations while eliminating long lab wait times. Our system delivers real-time benzene readings, giving facilities instant insight and immediate ability to respond.

Comparing Monitoring Methods

Refineries must choose between two options, and the differences are not subtle:

Passive Sampling:

• 14-day sample collection cycles

• Delayed lab analysis

• Limited ability to act on exceedances

• Reactive by design

  
  

Real-Time Monitoring:

• real-time benzene concentration data

• Immediate alerts for threshold exceedance

• Actionable in real-time, not retroactively

  
  

AirLogics provides a practical solution to a regulatory requirement. Our technology eliminates the risk of reacting too late. Facilities using our real-time systems can investigate sources of benzene and make operational changes while the problem is still happening—not two weeks later.

Why Refineries Work with AirLogics?

Let’s be direct: monitoring is happening only because it has to. The goal is simple—stay in compliance, avoid enforcement, and keep operations running. AirLogics is built around this reality. We provide reliable, EPA-accepted equipment and a fully managed service that makes compliance easier and faster.

Unlike passive systems, which give a slow snapshot, our solution provides continuous visibility. This helps facilities avoid accidental violations, reduce the risk of costly investigations, and maintain accurate reporting with no delays.

Smart Monitoring Needs Smart Tools

Our real-time system integrates with our own fenceline monitoring software, which allows facility teams to see trends, set alerts, and automatically generate reports formatted for EPA compliance. The software is designed to make environmental compliance less of a burden by turning raw air data into decision-ready information.

Closing Statement:

Fenceline monitoring is not optional. The regulation is clear, and enforcement is real. The only question is how your facility will respond to the requirement. Passive methods meet the rule, but they limit your ability to manage risk. Real-time monitoring, allowed under §63.658(k)(6), puts control back in your hands. AirLogics gives petroleum refineries the compliant, real-time tools needed to stay ahead of enforcement. If you're ready to upgrade your approach and avoid relying on slow, outdated sampling, reach out today.