concrete walls has hairline cracks

hello fellow tsikoters..

question, my sister is renting a 2 floor house apartment and when we visit the place, we notice that some of the walls has very tiny single hairline long cracks... are those cracks dangerous? we're thinking that the apartment might collapse or something.

hinde po siya spider type na cracks, single line lang..pero very tiny..halos hinde mo kita..

sorry just being paranoid..

TIA