Learn Turkish: Gelecek yıla kadar, bu kirlilik birçok insanda astımı tetiklemiş olacak. - By next year, this pollution will have triggered asthma in many people.

This is the Turkish Future Perfect tense. It is built by adding the past/perfective suffix -miş to the verb stem (tetikle-), followed by the future tense of the auxiliary verb olmak (olacak). Just like in English, it is used to describe an action that will be completed before a specific deadline in the future.

Why does kadar require the dative case in gelecek yıla kadar?

When the postposition kadar is used to mean "until," "as far as," or "by" a certain time, it always requires the preceding noun to be in the dative case (-(y)e/-(y)a). Therefore, yıl (year) takes the dative suffix -a.

Why is the locative case (-da) used in birçok insanda instead of a word for "inside"?

While English says "in many people," Turkish uses the locative case (-da/-de) to indicate where a disease, trait, or condition manifests. Using a spatial word like içinde (inside of) would sound unnatural, as if the pollution physically placed asthma into their internal organs, rather than them developing the condition.

Why does astım (asthma) take the accusative case here (astımı)?