EPA 608 Core study guide: Clean Air Act, refrigerant law, and venting rules

Core is the shared foundation: the Core section must be passed before any Type credential or Universal certification is issued, it supplies 25 of the 100 questions on the EPA 608 Universal practice test, and it tests federal law rather than service procedure.

What the EPA 608 Core section tests

The Core section tests every topic on the official EPA outline: ozone depletion, the Clean Air Act and Montreal Protocol, Section 608 regulations, refrigerant classification, the three R's, safety, and shipping. The table on this page maps each exam topic to the section that covers it:

The statute applies to any technician who opens a refrigerant circuit to service, maintain, repair, or dispose of equipment. For a one page review of every date and figure on this page, use the EPA 608 study guide cheat sheet.

Where technicians actually lose Core points

Core points are lost mainly on refrigerant identification, recovery equipment, and refrigerant blends, each missed more than one time in four in our practice data as of August 2026. The 75.7% signed in average reported at the top of this page clears the 72% pass mark by under four points, and the table on this page shows where the misses concentrate. These are our own practice numbers rather than official exam statistics.

Refrigerant identification carries more answers than any other Core topic (831) and is still missed 28.6% of the time; the chlorine rule in the refrigerant categories section on this page is the distinction those questions test. Ozone and the Montreal Protocol is second by volume (588 answers, 24.1% missed). The three R's, safety, and evacuation sit under 20% missed.

Venting prohibitions and civil penalties

Venting refrigerants into the atmosphere is prohibited under Section 608 of the Clean Air Act. For CFCs and HCFCs, the prohibition took effect July 1, 1992. For HFCs, it took effect November 15, 1995.

The prohibition has two effective dates that the Core exam specifically tests:

July 1, 1992. Venting of CFCs (chlorofluorocarbons) and HCFCs (hydrochlorofluorocarbons) became prohibited during service, maintenance, repair, and disposal of refrigeration and air conditioning equipment. R-12, R-22, R-11, and R-113 are covered from this date.

November 15, 1995. HFCs (hydrofluorocarbons) were added to the venting prohibition. R-134a, R-410A, R-404A, R-507, and all HFC blends become covered from this date.

The de minimis exemption: Section 608 does not treat every trace of refrigerant loss as venting. Releases that escape despite a good faith attempt to recover or recycle are de minimis. The rule states no quantity, so what the exam tests is the standard of practice, not a number: if it can be recovered, it must be. The de minimis exemption is the only practice based exception to the recovery obligation; the other three lawful releases on this page are exempt for other reasons.

Releases that do not violate Section 608. The exam tests four lawful releases alongside the prohibition itself:

• De minimis releases while making a good faith attempt to recover, recycle, or dispose of refrigerant
• Releases during normal equipment operation, such as a purge unit venting on a low pressure chiller, as opposed to releases during service
• Small releases when purging gauge manifold hoses; recovery and recycling equipment manufactured after November 15, 1993 must have low loss fittings to minimize this
• Release of a CFC or HCFC that is not being used as a refrigerant, such as an R-22 and nitrogen mix used as a holding charge (you may not add nitrogen to refrigerant to claim this exemption)

Who can report violations: any person, including fellow technicians, building owners, or environmental advocacy groups, may report Section 608 violations. The EPA does not require the reporter to be an inspector or agency employee. This is the citizen suit provision and is frequently tested.

Refrigerant categories: CFCs, HCFCs, HFCs, HFOs

The Core section tests refrigerant classification by ozone depletion potential (ODP) and global warming potential (GWP). Four categories appear:

CFCs (chlorofluorocarbons): highest ODP, fully phased out from production in the United States. Examples: R-11, R-12, R-113. The 1987 Montreal Protocol mandated the CFC phaseout. CFCs may still exist in older equipment.

HCFCs (hydrochlorofluorocarbons): lower ODP than CFCs but not zero. R-22 is the most commonly tested HCFC. R-22 new equipment production ended January 1, 2010, and all R-22 production ended January 1, 2020. Reclaimed R-22 is still legal for servicing existing equipment.

HFCs (hydrofluorocarbons): zero ODP but high GWP. Covered by the Section 608 venting prohibition since 1995. R-410A, R-134a, and R-404A are common HFCs. The AIM Act mandates an HFC phasedown, with the R-410A new equipment ban effective January 1, 2025. The phasedown steps HFC production down 85% by 2036, and the A2L refrigerants R-32 and R-454B are the replacements now shipping in new residential equipment.

HFOs (hydrofluoroolefins): zero or near zero ODP and very low GWP. R-1234yf (automotive) and R-1234ze are examples. HFOs and HFO blends (A2L refrigerants like R-454B and R-32) are the next generation replacements. The Type 2 study guide covers how the exam tests the R-22 to A2L transition.

Ozone depletion and the Montreal Protocol

Ozone depletion is the chain reaction in which chlorine released from CFC and HCFC refrigerants destroys stratospheric ozone: one chlorine atom destroys about 100,000 ozone molecules before it degrades, and that chain reaction is why venting is a federal offense. The Core exam tests the mechanism, not just the vocabulary.

• Where ozone matters: ozone in the stratosphere filters UV radiation and is protective. Ozone in the troposphere, near ground level, is smog and a pollutant. The exam asks you to distinguish the two.
• UV health effects: increased skin cancer, eye cataracts, and weakened immune systems are the tested consequences of ozone depletion.
• Evidence it is manmade: chlorine monoxide in the stratosphere is short lived, so its presence proves an ongoing chlorine source. Natural chlorine dissolves in rain and never reaches the stratosphere; CFC molecules do not, and release chlorine only when UV breaks them apart at altitude.

The regulatory response is a timeline the Core exam tests date by date:

Recovery, recycling, and reclamation

Recovery means removing refrigerant from a system into an external container without testing or processing it. Recycling means cleaning refrigerant for reuse on site. Reclamation means processing refrigerant to the AHRI 700 purity standard, and only EPA certified reclaimers may reclaim. AHRI 700 is the current name of that standard; older study material calls it ARI 700, and both names mean the same purity specification.

Recovery: removing refrigerant from a system and storing it in an external container, without necessarily testing or processing the refrigerant. Any certified technician performs recovery on site using approved recovery equipment. The recovered refrigerant does not need to meet any purity standard at the time of recovery.

Recycling: cleaning recovered refrigerant using oil separation and single or multiple passes through filter driers. Recycling occurs on site or at a facility. Recycled refrigerant meets a reduced contaminant standard but NOT the AHRI 700 purity standard required for sale as new refrigerant. Recycled refrigerant may only be returned to the original owner's equipment.

Reclamation: reprocessing recovered refrigerant to AHRI 700 purity standards, the same standard as virgin refrigerant. Reclamation must be performed at an EPA certified reclamation facility. Only reclaimed refrigerant may be sold to a different owner. A certified reclaimer issues the purity documentation.

The Core exam frequently asks which process is required before selling refrigerant (reclamation), which process can be performed on site (recycling), and which process must be performed by a third party EPA certified facility (reclamation).

Safety, cylinders, and shipping

Safety on the Core exam comes down to three cylinder rules: recovery cylinders are gray with a yellow top, disposable cylinders are never refilled, and no cylinder is filled past 80% of liquid capacity. The rest of the safety material follows the same pattern of short, absolute rules.

Cylinder rules:

• Refillable recovery cylinders are DOT approved, gray with a yellow top, and are the only cylinders used for recovered refrigerant
• Disposable cylinders (DOT Specification 39) are single use. Refilling one is a violation; empty them to zero pressure and render them unusable
• Never fill any cylinder beyond 80% liquid capacity, to leave room for expansion
• Never apply open flame or direct heat to a refrigerant cylinder
• Never mix refrigerants in a recovery cylinder; a mixed cylinder usually cannot be reclaimed

Exposure and PPE: wear safety glasses and gloves whenever refrigerant can escape; liquid refrigerant at atmospheric pressure causes frostbite. Refrigerant vapor is heavier than air and displaces oxygen in confined spaces, so ventilate first and use a self contained breathing apparatus (SCBA) where a large release is possible. Open flames and hot surfaces decompose refrigerant into hydrochloric acid, hydrofluoric acid, and phosgene gas, so recover refrigerant before soldering or welding on a circuit.

Leak detection: pressure test with dry nitrogen, never with compressed air or oxygen; compressed oxygen in contact with refrigerant oil is explosive. Always use a pressure regulator and a relief valve on a nitrogen cylinder, and never install relief valves in series. If a pressure test cannot locate the leak, the EPA allows a trace gas as a last resort: nitrogen with a small amount of the system's refrigerant, found with an electronic detector.

Shipping: refrigerant cylinders ship as DOT hazardous materials. They must carry a DOT classification tag identifying the refrigerant, travel secured upright, and refillable cylinders must be hydrostatically retested every five years. The Type 1 study guide covers the recovery equipment requirements that build on these rules.

Who can buy refrigerant: the sales restriction

The sales restriction in 40 CFR Part 82 limits the purchase of regulated refrigerants to EPA 608 certified technicians. Wholesalers must verify certification before selling and retain sales records, which is why distributors ask for your card number at the counter. The exam tests this as a one line fact: sale of CFC, HCFC, and HFC refrigerants is restricted to certified technicians, and an employer's certification can cover technicians buying on its behalf. That rule is what makes the certification itself legally meaningful, and it is why Core plus at least one Type section is the minimum credential for field work.

The refrigerant lifecycle

The refrigerant lifecycle is the six stage path from production to reclamation sale, and Section 608 attaches a requirement to every stage:

The sequence is the Core section's underlying logic: refrigerant moves from production through use, must be recovered before equipment is opened, must be reclaimed before it can be resold, and is never vented at any stage.

Core section FAQ