# What is the maximum air cell height for Class A eggs? > For Class A, the egg air cell may be at most 6 mm high and must be stationary (RIISPOA, art. 225, II). The European Union uses the same 6 mm limit (Delegated Regulation (EU) 2023/2465, art. 3(1)(b)). The air cell is seen only by candling: a surface camera cannot measure it. Updated: 2026-10-09 · URL: https://vigiovo.com/en/resources/egg-air-cell · Português: https://vigiovo.com/recursos/camara-de-ar-do-ovo.md ## Key takeaways - For Class A, the air cell is at most 6 mm high and must be stationary (RIISPOA, art. 225, II). - The European Union uses the same 6 mm limit and allows at most 4 mm for eggs sold as extra (art. 3(1)(b)). - The air cell is seen only by candling, because it sits inside the egg and the light must pass through the shell. - Vigiovo does not measure the air cell: it works on the shell and leaves the inside to candling. ## What is the air cell limit for Class A? For Class A, the [air cell](https://vigiovo.com/en/resources/glossary#air-cell) may be at most 6 mm high and must be stationary. RIISPOA sets both requirements in item II of art. 225, alongside the requirements for the shell, the yolk and the white. The European rule has the same limit: the air space may not exceed 6 mm in height and must be stationary (Delegated Regulation (EU) 2023/2465, art. 3(1)(b)). The EU adds a stricter limit for eggs marketed as extra, which may not exceed 4 mm (art. 3(1)(b)). In practice, the check looks at the height of the air cell and whether it moves when the egg is turned. An air cell that shifts freely shows the egg does not meet the stationary requirement, even if its height looks within the limit. ## Why is the air cell seen only by candling? The air cell sits inside the egg, at the broad end, between the shell membranes. To see it, the egg must be lit from behind, as in [candling](https://vigiovo.com/en/resources/glossary#candling). The light passes through the shell and shows the edge of the air cell and whether it moves. A surface camera looks at the shell in reflected light. It sees shape and dirt, but it does not pass through the shell, so it cannot measure the air cell. That is a limit of the method, not a matter of calibration. For that reason, the air cell belongs on the candling side of the comparison. See [candling or computer vision](https://vigiovo.com/en/resources/candling-vs-computer-vision) for what each method detects. ## Why does the air cell grow over time? The air cell grows because the egg slowly loses moisture through the shell, and the air space at the broad end increases. The longer the time since laying, the larger the air cell tends to be, which is why the age of the egg matters in grading. On the farm, more frequent collection reduces the time the egg spends in the nest, and proper cooling slows the loss of moisture. These practices do not replace measurement: the air cell can only be confirmed by candling, egg by egg. ## How does the air cell fit into camera-based grading? Vigiovo does not measure the air cell. The system works on the shell: it separates dirt, cracks and shape, and sends to manual review the eggs it cannot see whole. The air cell check is still done by candling, which the law requires in registered establishments (RIISPOA, art. 223, II). This split is why a camera is complementary. It removes visibly dirty and cracked eggs from the line, and candling checks the inside of what remains. A camera cannot confirm that an egg meets the 6 mm limit, and it should not be presented as if it could. For the other interior requirements of Class A, such as the yolk and the white, see [Brazil's Class A eggs](https://vigiovo.com/en/resources/brazil-category-a-eggs). ## Frequently asked questions ### What is the air cell limit for Class A eggs? Under Brazilian rules, the air cell of a Class A egg may not exceed 6 mm in height and must be stationary (RIISPOA, art. 225, II). The European Union uses the same 6 mm limit and at most 4 mm for extra eggs (Delegated Regulation (EU) 2023/2465, art. 3(1)(b)). ### Can a camera measure the air cell? No. A surface camera sees the shell in reflected light and does not pass through it, so it cannot measure the air cell. That measurement requires candling, with the egg lit from behind. Vigiovo does not make this measurement and leaves the inside to candling. ### Why does the air cell get bigger with time? The egg slowly loses moisture through the shell, and the air space at the broad end grows. The longer the time since laying, the larger the air cell tends to be. Proper cooling and frequent collection slow this process on the farm. ## Sources - [Decreto nº 9.013/2017 (RIISPOA)](https://www.planalto.gov.br/ccivil_03/_ato2015-2018/2017/decreto/d9013.htm), Presidência da República (Brasil) - [Delegated Regulation (EU) 2023/2465, marketing standards for eggs](https://eur-lex.europa.eu/eli/reg_del/2023/2465/oj/eng), EUR-Lex ## Read next - [Leaker eggs: definition, risks and destination](https://vigiovo.com/en/resources/leaker-eggs.md) (Explainer, 2026-10-09): What a leaker egg is under 7 CFR 57.1, why RIISPOA makes it unfit for consumption, what a camera can see and how to handle it on the line. - [Hairline cracks in eggs: why cameras miss them](https://vigiovo.com/en/resources/hairline-cracks-in-eggs.md) (Explainer, 2026-10-09): What a hairline crack in an egg is, why it does not show under normal light, how candling and acoustic testing reveal it and what Vigiovo detects. - [How to identify cracked eggs: types, methods and rules](https://vigiovo.com/en/resources/how-to-identify-cracked-eggs.md) (Guide, 2026-10-09): What a cracked egg (check) is, how it differs from a leaker, which methods detect each kind of crack and where cracked eggs must go under the regulations. ## How Vigiovo helps Vigiovo grades eggs on the conveyor as clean, dirty, cracked or unverified, in real time, with deterministic computer vision: every decision comes with the measurements behind it, on an ordinary CPU. https://vigiovo.com/en/how-it-works.md 4 min read.