Learn Hardcore Italian: Il riciclo in casa è importante per la salute. - Recycling at home is important for health.

Here riciclo is a mass (uncountable) noun meaning “recycling” in general. Mass nouns in Italian stay in the singular and usually take the definite article. If you wanted to refer to individual recycling actions or types, you could theoretically say i ricicli, but that’s uncommon in everyday speech.

What does in casa mean, and could I use a casa instead?

Both translate as “at home,” but with a nuance:

in casa emphasizes being inside the house (“within the home environment”).
a casa often implies going home or being at home in a broader sense.
In this sentence, in casa highlights the household context where recycling happens.

Why is the verb written è with an accent instead of e?

è (with grave accent) is the third-person singular of essere (“to be”). Without the accent, e is the conjunction “and.” The accent marks the difference between “is” and “and.”

Why is importante ending in -e? Does it agree with gender?

Adjectives ending in -e have one form for both masculine and feminine singular: importante. Their plural form is importanti (for both genders). So you don’t change importante whether you modify a masculine or feminine noun in the singular.

Why do we say per la salute instead of per salute?

When speaking generically about health, Italian uses the definite article. la salute = “health” as a general concept. Dropping la (per salute) would sound unnatural and is not standard in Italian.

Can I specify whose health I mean, for example per la nostra salute?

Yes. To say “for our health,” you add the possessive and agree it with salute (feminine singular):
Il riciclo in casa è importante per la nostra salute.

Is riciclo the same as riciclaggio?

Not exactly. riciclo is the preferred everyday term for material recycling. riciclaggio can also mean “recycling,” but it’s less common in environmental contexts and is often used for “money laundering.” Italians usually say riciclo when talking about bottles, paper, etc.

Why don’t we use nel or nella before casa (e.g., nella casa)?

in casa is a fixed locution meaning “at home.” You don’t combine in with the article here. If you specify which house, you’d use the article: nella casa di Marco (“in Marco’s house”). But in the general sense of “home,” you drop it.

Could I change the word order, for example, È importante il riciclo in casa per la salute?

That’s grammatically possible, but it sounds less natural. Italian prefers the subject–verb–adjective order in this case:
Il riciclo in casa è importante per la salute.
Moving è importante to the front makes the sentence more emphatic or poetic.