Learn Hardcore Portuguese (Portugal): Usar máscara nos transportes ajuda a evitar o contágio entre desconhecidos. - Wearing a mask on public transport helps avoid contagion between strangers.

In Usar máscara, is usar an infinitive being used like a noun, similar to “Using a mask” in English? Is this structure common in Portuguese?

Yes. Usar is the infinitive form of to use, and here Usar máscara acts as the subject of the sentence, just like “Wearing a mask” or “To wear a mask” in English.

Structure:

Usar máscara = subject
ajuda = verb
a evitar o contágio entre desconhecidos = rest of the predicate

So literally: “To use a mask on transport helps to avoid contagion between strangers.”

Using a bare infinitive as a subject is very common in Portuguese, especially in more formal or neutral written language:

Fumar faz mal à saúde. – Smoking is bad for your health.
Ler ajuda a reduzir o stress. – Reading helps reduce stress.

You could also say O uso de máscara nos transportes ajuda…, which is a more formal, noun-based version: “The use of masks on transport helps…”

Why is there no article before máscara? Could I also say usar uma máscara? Is there any difference?

Both are possible:

Usar máscara nos transportes…
Usar uma máscara nos transportes…

The difference is subtle:

Usar máscara (no article)
- Generic, habitual action.
- Focus on the practice in general, not on a specific physical mask.
- Very common in rules, recommendations, and public health language:
  - Usar cinto de segurança é obrigatório. – Wearing a seat belt is mandatory.
  - Tomar pequeno-almoço é importante. – Having breakfast is important.
Usar uma máscara
- Slightly more concrete, like “wear a (single) mask”.
- You would often see this in instructions to an individual:
  - Deve usar uma máscara dentro do autocarro. – You must wear a mask on the bus.

In this sentence, usar máscara sounds more general and policy-like, which fits the public-health style. In European Portuguese, omitting the article in these generic, rule-like phrases is very natural.

What exactly does nos transportes mean? Is it specifically on public transport? Why is transportes plural?

Nos transportes here means “on public transport”, or more literally “in the means of transport”.

Breakdown:

em + os = nos
transportes = plural of transporte, meaning “means of transport”.

In European Portuguese, os transportes (often short for os transportes públicos) is a common way to refer to the whole system: buses, trains, metro, trams, etc.

Examples:

Vou de transportes para o trabalho. – I go to work by public transport.
Há muitas pessoas nos transportes à hora de ponta. – There are many people on public transport at rush hour.

It’s plural because it refers to various modes of transport collectively, not a single vehicle.

Is nos always “in the”? How does em + os normally work?

In this sentence, nos = em + os and is best translated as “on the” or “in the”, depending on the context.

Common contractions with em:

em + o = no
- no autocarro – on the bus / in the bus
em + a = na
- na escola – at school / in the school
em + os = nos
- nos transportes – on public transport
em + as = nas
- nas ruas – in the streets

The exact English preposition (in/on/at) depends on the noun and context, but in Portuguese the contraction with em is very regular.

Why is it ajuda a evitar and not ajuda evitar or ajuda em evitar?

In European Portuguese, the normal pattern is:

ajudar a + infinitive

So:

ajudar a evitar – to help to avoid
ajudar a resolver – to help to solve
ajudar a entender – to help to understand

Using ajuda evitar without a is generally considered Brazilian usage or less standard; in Portugal, ajuda a evitar is the natural form.

Ajuda em evitar is not correct in this structure.

So:

Usar máscara nos transportes ajuda a evitar o contágio…
= Wearing a mask on public transport helps (to) prevent contagion…

Why is it o contágio with the definite article? Could we also say evitar contágio without o?

Yes, you could see both:

ajuda a evitar o contágio…
ajuda a evitar contágio…

The version with the article, o contágio, is more common and feels more natural in standard European Portuguese here. Reasons:

Abstract nouns (like contagion, pollution, crime) are often used with the definite article when speaking in a general sense:
- O crime está a aumentar. – Crime is increasing.
- A poluição é um problema. – Pollution is a problem.
- O contágio é um risco. – Contagion is a risk.
Evitar o contágio sounds like “avoid the phenomenon of contagion (in general)”.

Without the article:

evitar contágio feels a bit more technical or clipped, as if “contagion” is a type of event, almost like avoid any contagion, but it’s less idiomatic than evitar o contágio in everyday style.

Why is contágio singular here? Could I say os contágios in the plural?

In this context, contágio is a mass/abstract noun, referring to the process or phenomenon of contagion in general, not to individual infection events. That’s why it is singular and uncountable.

evitar o contágio ≈ avoid contagion (as a process).

Os contágios (plural) would mean individual, countable cases of contagion. You might see it in more technical or statistical contexts:

Registaram‑se vários contágios na escola. – Several contagion events were recorded at the school.

But in a general recommendation like this sentence, the singular o contágio is the natural choice.

What nuance does entre desconhecidos have? Is it the same as entre estranhos (“between strangers”)?

Both desconhecidos and estranhos can translate as “strangers”, but the nuance differs slightly:

desconhecido
- Literally: unknown.
- Focus on people you don’t know personally.
- Neutral tone.
- entre desconhecidos = among people who do not know each other.
estranho
- Also “strange”, “odd”, or “weird”.
- As a noun (um estranho), it can mean “a stranger”, but often carries a slightly more emotional or suspicious tone in some contexts.
- entre estranhos is understandable, but in this health-policy type sentence, entre desconhecidos feels more neutral and formal.

Also, desconhecidos is masculine plural but used generically, referring to people of any gender, just like “strangers” in English.

Could I move nos transportes to another place in the sentence, like Usar máscara ajuda a evitar o contágio nos transportes entre desconhecidos? Does the word order change the meaning?

Yes, you can move nos transportes. All of these are grammatically possible:

Usar máscara nos transportes ajuda a evitar o contágio entre desconhecidos.
– The location (nos transportes) is attached to usar máscara, i.e. wearing a mask on transport.
Usar máscara ajuda a evitar o contágio nos transportes entre desconhecidos.
– Now nos transportes is closer to o contágio, so it can be read as “contagion on transport”. The overall meaning is still clear and similar.
Usar máscara ajuda, nos transportes, a evitar o contágio entre desconhecidos.
– More written/formal; nos transportes is an inserted phrase, emphasising “in the context of transport”.

In practice, the original version is clear and natural. Moving nos transportes later in the sentence lightly shifts the focus but doesn’t really change the essential meaning.

Could Portuguese also use a gerund here, like Usando máscara nos transportes ajuda…, parallel to English “Wearing a mask on transport helps…”?

No, that would not be natural.

In Portuguese, the gerund (usando) is not normally used as the subject of a sentence. For this function, Portuguese strongly prefers the infinitive:

Usar máscara nos transportes ajuda… ✅
Usando máscara nos transportes ajuda… ❌ (unnatural)

The gerund in Portuguese is more for:

Ongoing actions: Estou a estudar / Estou estudando.
Circumstantial clauses: Chegou sorrindo. – He/she arrived smiling.

So where English has “Wearing a mask helps…”, Portuguese uses “Usar máscara ajuda…”, not a gerund.

Pronunciation-wise, are there any tricky parts in Usar máscara nos transportes ajuda a evitar o contágio entre desconhecidos for an English speaker?

Yes, a few points typical of European Portuguese:

Usar
- Final r is soft and often almost inaudible in European Portuguese.
- Roughly [uˈzaɾ], but the r may be very light.
máscara
- Stress on the first syllable: MÁS‑ca‑ra: [ˈmaʃ.kɾɐ].
- s between vowels becomes [ʃ] (like “sh”).
- Final a is reduced and sounds closer to ɐ.
nos transportes
- nos has a nasal vowel: [nuʃ] (in many accents).
- trans‑ is nasal: [tɾɐ̃ʃ] or [tɾɐ̃ʃʔ].
- Final s in transportes is often [ʃ].
ajuda
- j is like the English “zh” in “measure”: a‑ZHOO‑da – [ɐˈʒuðɐ].
evitar / contágio / entre / desconhecidos
- e at the beginning of unstressed words often sounds like ɨ or ɐ: [ɨviˈtaɾ] (evitar), [ˈẽtɾɨ] (entre).
- contágio: stressed tá syllable: [kõˈtaʒju]; note the nasal con‑.
- desconhecidos: approx. [dɨʃkuɲɨˈsiduʃ].

European Portuguese has lots of vowel reduction and nasalisation, so even if it looks similar to Spanish, it sounds more “closed” and less clearly articulated to English ears.

Is the overall tone of this sentence formal, informal, or neutral? Would it be suitable for a public notice or official recommendation?

The tone is neutral to slightly formal, and it is absolutely suitable for a public notice, public-health recommendation, or official document.

Reasons:

Use of infinitive as subject (Usar máscara…) – common in rules and recommendations.
Generic, impersonal language – no tu, você, or o senhor / a senhora.
Vocabulary like contágio and desconhecidos is standard and neutral.

You might see very similar phrasing on posters from health authorities in Portugal.