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This article was originally published in the 2026 issue of TRANSCAER Today. It is republished here with permission and with slight changes. The opinions, claims, conclusions, and positions expressed in this post are those of the author or person quoted and do not necessarily reflect the opinions of the editors, AIHA, The Synergist, or SynergistNOW.

At the AIHA Guideline Foundation, emergency response planning for chemical and radiological incidents is undergoing a profound transformation, and Emergency Response Planning Guidelines (ERPGs) are at the center of it. As organizations modernize their risk management strategies, AIHA’s ERPG program, coupled with a new generation of digital tools and training, is reshaping how industry, responders, and communities prepare for low‑probability, high‑consequence events.  

ERPGs are airborne concentration thresholds developed by the Guideline Foundation to support emergency planning for short‑term, one‑time exposures to toxic chemicals. They estimate the concentrations at which nearly all members of the public (excluding the most sensitive) are expected to experience specific tiers of health effects over about one hour of exposure.  

Each substance can have up to three values: ERPG‑1 for mild, transient effects or noticeable discomfort; ERPG‑2 for serious but reversible effects that should not impair an exposed person’s ability to take protective action; and ERPG‑3, which is the maximum one-hour exposure without developing life‑threatening health effects. These values are derived from available toxicology data, human experience, existing exposure guidelines, and a transparent review process managed by the Guideline Foundation. 

ERPGs are referenced in EPA’s risk management program rule and are built into widely used tools like the CAMEO suite and the National Oceanic and Atmospheric Administration’s ALOHA air hazard modeling program, where they serve as levels of concern for dispersion modeling and threat‑zone estimation. ERPGs are now routinely used to assess the adequacy of accident prevention and emergency response plans across fixed facilities, transportation corridors, and community emergency planning programs.  

Celebrating 40 Years

AIHA’s Emergency Response Planning Guidelines (ERPGs) were first integrated into AIHA activities in 1987, so they will mark their 40th anniversary in 2027. AIHA established an ERPG Committee in the mid-1980s to develop scientifically grounded, community-focused guidance values for acute chemical exposures. By 1987, the ERPG initiative was formally integrated into AIHA, making 2027 the 40-year milestone of ERPGs as an AIHA-sponsored program.

Over time, ERPGs have expanded in both the number of covered substances and the robustness of their documentation, moving from a relatively small set of high-concern industrial chemicals to a broad portfolio covering 150 chemicals used by industry, government, and emergency planners. Methodologies have evolved in parallel with toxicology and risk assessment science, including more systematic literature reviews, clearer criteria for endpoint selection, and attention to sensitive subpopulations.

ERPGs are scientifically durable and have remained relevant through routine review and updates. Transparency of the process, including how decisions are made in setting ERPG values and soliciting public comment for new or changing values, is a guiding principle in setting ERPGs. Generations of industrial hygienists, emergency planners, and emergency responders have used ERPGs to make risk-critical decisions that protect both responders and the public. ERPGs are the only currently updated exposure limits used in emergency response.  

Bringing ERPGs to Life: The New Web Experience

Historically, one barrier to broader ERPG adoption has been access, usability, and integration into day‑to‑day tools. In 2025, the Guideline Foundation removed those barriers by offering the ERPG values and technical supporting documentation free of charge on a new web application.  

The emerging solution is a dedicated ERPG web presence—anchored at AIHA’s ERPG program site—that serves as a front door to the guidelines, supporting materials, and related digital tools. This modern ERPG‑centric web app and website provide access to current ERPG values, reference documents, and technical rationales for each chemical; link ERPG values directly to modeling workflows that use tools like ALOHA or CAMEO, where ERPG‑1, ‑2, and ‑3 values define yellow, orange, and red threat zones; and offer clear guidance on how to use ERPGs for transportation emergencies, fixed‑facility incidents, and community planning scenarios.  

By positioning ERPGs within an intuitive web interface, organizations no longer need to treat them as a specialist reference used only by a few experts. Instead, they can be embedded in everyday planning templates, risk‑assessment workflows, and cross‑functional emergency drills.

A typical workflow might look like this: an emergency planner selects a chemical from a dropdown, sees its ERPG‑1/‑2/‑3 values, launches a dispersion model, and then exports maps and protective‑action zones for inclusion in both plant‑level and community plans.

Training: Turning ERPG Awareness into Competence

Technical values alone do not improve outcomes unless the workforce knows when and how to use them. Recognizing this, the Guideline Foundation has supported the development of a dedicated ERPG e-learning course tailored to emergency response professionals. This 1.5-hour course was made possible through a grant from the Department of Transportation administered by TRANSCAER.  

The course introduces the fundamentals of ERPGs, their role in chemical and radiological incident management, and how ERPG awareness supports pre‑incident planning, inter‑agency coordination, and safer decision‑making during actual events. The self‑paced format allows responders, planners, and industrial personnel to fit learning into busy schedules while still achieving a consistent baseline of understanding.  

Within a comprehensive training program, the ERPG course serves as a foundation for:

• integrating ERPGs into incident command system- and national incident management system‑based emergency management training
• running realistic tabletop exercises in which participants interpret ERPG‑based threat zones and make time‑critical protective‑action decisions
• aligning plant‑level, corporate, and community planning teams on a common risk language and action framework

For organizations that already deliver hazardous materials and process safety training, the ERPG course offers a focused way to elevate community‑protection considerations and link them directly to technical modeling and planning tools.

Responding to Emerging Threats: Lithium-Ion Battery Fires

AIHA’s ERPG Working Group is responding to the hazard scenario posed by lithium‑ion battery fires. The specialty working group will examine combustion products from fires involving lithium‑ion batteries and is reviewing emerging science on off‑gassing, toxic byproducts, and dispersion to understand how existing ERPG values (for example, for hydrogen fluoride) perform in battery‑fire scenarios and where new guidance might be needed.

This work aligns with growing national concern about lithium‑ion incidents and thermal runaway, which can release hydrogen fluoride, hydrogen chloride, carbon monoxide, particulates, and other hazardous species during fires. Outputs from the task force could help clarify how ERPGs are applied in plume modeling, response zoning, and protective action decisions around battery‑energy‑storage facilities, warehouses, and consumer settings.

A Tribute to Our Volunteers and Supporters

ERPG work is fundamentally volunteer powered: every guideline, technical supporting document, and update is produced through the unpaid effort of passionate subject matter experts who donate their time and professional judgment. The Guideline Foundation supports industrial hygienists, toxicologists, emergency planners, physicians, regulators, and other technical volunteers by accommodating in-person meetings, providing web resources, and publishing and staff support.  

The Guideline Foundation has been a proud sponsor of TRANSCAER and is grateful for the DOT grants that have funded library research and e-learning.

Looking Ahead

For 40 years, ERPGs have helped emergency planners make informed, science-based decisions that protect communities. With free public access, modern digital tools, expanded training, and continued volunteer leadership, the ERPG program is well positioned to meet today’s risks—and those that lie ahead.

To learn more about ERPGs, visit the AIHA Guideline Foundation website and view the ERPG values and links to technical supporting documents.