<prompt> Translate the following text to SwahiliAssessment of deaths attributable to air should we use risk estimates based on time series or on cohort studies?  <response>: Uhakiki wa vifo vinavyoweza kuhusishwa na hewa je, tunapaswa kutumia makadirio ya hatari kulingana na mfululizo wa wakati au juu ya masomo ya kundi? 