<prompt> Translate the following text to EnglishFomu ya kazi ya kweli ya vifo vya PM haijulikani, lakini uchambuzi huu unadhani kazi ya CR kuwa na fomu ya log-linear kama inavyotokana na fasihi katika safu husika ya mfiduo.  <response>: The shape of the true PM mortality C-R function is uncertain, but this analysis assumes the C-R function to have a log-linear form as derived from the literature throughout the relevant range of exposures. 