From today, airports with standard C3 machines, which until now had allowed liquids exceeding 100 ml to be carried in hand luggage, will reintroduce the 100 ml limit in hand luggage.

In this post I hope to answer exhaustively all the questions that, over the years, many people have asked me.

Liquids: What are they?

It seems like a stupid question, but it is not. We commonly talk about liquids, but the definition given by the legislation is more specific. Liquids, normatively speaking, are identified with the acronym LAG, or Liquids, Aerosols and Gels. Now let’s see how the 3 categories are identified:

• Liquids: anything that is liquid, such as drinks (water, Coca-Cola, Sprite, fruit juices…) oil, vinegar, e-cigarette liquid, syrups, perfumes,…
• Aerosol: all those containers containing liquefied gas under pressure such as spray deodorants, shaving foam, spray cream, hairspray, dry shampoo…
• Gel: substances with a pasty, malleable and spreadable consistency such as hair gel, Nutella, pesto, ragù, toothpaste, almond cream, jams, pistachio cream, body/face creams, liquid soaps…

As you can see, the definition of liquid is much more complicated than you might think, and even things that we wouldn’t consider liquids, such as ragù, Nutella, creams, hairspray… are not permitted by law.

Why does the 100ml rule exist?

The rule was introduced in 2006, following a terrorist plan to detonate liquid explosivesdisguised as soft drinks (Lucozade, specifically) on flights to the UK, Canada and the US. Following this discovery, all liquids were initially banned from carry-on luggage (some UK airports banned carry-on luggage altogether) and the now familiar 100ml limit was subsequently introduced.

Why was the 100ml limit removed at some airports and why did they reintroduce it today?

The limit was removed because, thanks to new-generation machines that exploit advanced technologies, it was possible to check the liquid, even if it was greater than 100 ml, directly in the baggage, without having to remove it. Only in some cases was the additional check required.
This greatly speeded up the process and therefore allowed both control of the liquid and a speed that ensured an adequate flow of people.

The same limit was reintroduced because the European Union, the same one that had certified these machines for the control of liquids, realized that they did not meet the expected performance standards and that they did not guarantee an effective and reliable control of liquids. Initially it was thought that a software update could solve the situation in a short time, but the problem turned out to be bigger than expected and the certifications that allowed the control of liquids greater than 100 ml were withdrawn, reintroducing it again as a limit.

What is the 100ml rule?

The regulation says that all liquids must be in containers not exceeding 100 ml and placed in a transparent 1-liter bag, which must be closed and placed separately from the luggage (separately means neither above nor below the luggage, ideally they go in a separate tray). Only one bag of liquids per person is allowed. All liquids that do not fit in the bag are not allowed and must be thrown away, even if less than 100 ml.
Why did I put it in bold? containers not exceeding 100 ml? Because the law says that the quantity indicated on the container is valid, not the liquid inside it. If the container is 150 ml, but is full for a third of the maximum capacity, for regulatory purposes, that is a 150 ml liquid and, as such, must be thrown away. This is because we have no way of verifying the exact quantity of liquid inside a container and, in these cases, the law opts for the safest option, that is, throwing away the liquid. The same thing applies to containers without indications of the quantity of liquid contained, for example because the label is ruined or is part of a larger package and it is not written on the individual container, in this case even if it is clearly smaller than 100 ml it must be thrown away.

Are there exceptions to this rule?

Yes, there are categories of liquids that are allowed even if they are greater than 100 ml. In these cases the permitted liquid must be checked with a specific machine for checking liquids.

• Liquids for children under 10: Liquids are allowed for children under 10. For example, things like water, milk, baby food and various baby food, fruit juices. In theory, soft drinks like tea, Coca-Cola, Fanta, Sprite and things like Nutella, pistachio cream and so on are not included in the permitted liquids as they are considered non-essential and easy to find at the airport. In practice, water is fine because it is necessary, Coca-Cola or Nutella is a "whim" and it is not allowed. Obviously the liquids must be for children, it is not like just because you are traveling with a child you can bring limoncello or Cynar.
• Medicines and liquids for medical purposes: medicines larger than 100 ml are allowed, such as syrups, medical creams, liquids for contact lenses, hand sanitizer, medical or specific soaps (pharmacy ones), hydrogen peroxide and disinfectants in general. For example, the mouthwash of the captain’s pasta is not a medicine and should be thrown away, Tantum Verde is fine, similarly Garnier anti-dandruff shampoo is not a medicine, while the specific shampoo for psoriasis is.
• Foods for those who are on special diets: for example, a person who has had surgery and can only eat liquid foods such as baby food or yogurt, diabetics who bring sugary drinks out of necessity, or in any other case of medical necessity. Obviously it must be demonstrable, if you show up for checks with a bottle of Coca-Cola and say you are diabetic and then you have neither insulin, nor a microinfusor, nor a glucometer, nor any type of medicine for diabetics, the bottle is thrown away.
• Liquids purchased in Duty-Free shops and sealed in the appropriate bag: if you have purchased a liquid at the airport in Duty-Free shops after the security checks, in case you have a stopover, you can ask to put your purchase in a special tamper-proof bag that will allow you to bring that liquid even if you have to go through security again. For example, you leave from Milan, go to Barcelona for 3 days, then to Lisbon for 2 days and finally return to Milan. When you leave from Barcelona airport you buy a bottle of orujo, but then once in Lisbon you will leave the airport and when you return 2 days later you will have to go through security again and a 750 ml bottle of liquor would not pass the security checks. So you put it in this special tamper-proof bag so once in Lisbon you can go through security with the liquor. Obviously, if the bag is not intact or is tampered with in any way, everything is thrown away.

If you have the ability to control fluids, why not do it with all of them?

It’s a question that comes naturally and that quite a few people ask.

The problem with this is timing. A liquid check involves the baggage check procedure, plus the liquid check procedure. A single liquid check takes between 10 and 40 seconds, assuming everything goes smoothly, but if not, it can take two or more minutes, plus the baggage check time.
Making a fairly conservative assumption, let’s say that each person brings 3 liquids over 100 ml (a small bottle of water, shower gel and shampoo), which will take a minimum of 30 seconds up to 2 minutes to check the liquids. Plus let’s add the time for the baggage check, we’re talking about a minimum of 1 minute up to 3 minutes for the entire check and this is assuming that everything goes smoothly and without a hitch.

This means that one person would pass every 3 minutes, which would be absolutely not feasible, a plane with 200 people would take over 10 hours to pass. Even if they had 20 machines available (more than many airports, even the largest, have) for the controls, it would still mean that 200 people would take minimum half an hour. Considering that the peak flow of people in large airports varies between 1200 and 1500 people per hour, you understand that something like this would be absolutely unmanageable. The line to go through security checks would be well over 3-4 hours, a time that is unacceptable, also considering the possible times for checking in, sending hold luggage and passport control, we would be talking about a total of over 6 hours.
And these figures only take into account the slowdown due to the control of liquids and always assuming that everything goes smoothly, let’s also add the fact that random checks must be carried out in any case, plus the checks on prohibited objects such as knives and weapons plus general checks for various other reasons, you understand well that the thing is not in the least feasible.