<prompt> Translate the following text to EnglishMabadiliko ya viwango vya PM katika viwango vya chini ya 0.25 mg kwa m3 katika miaka ya 2010 na 2020, lakini maboresho makubwa zaidi kwa asilimia kubwa ya idadi ya watu, ikiwa ni pamoja na maboresho zaidi ya 2 mg kwa m3 kwa watu zaidi ya milioni 24 ifikapo mwaka 2020.  <response>: , changes in PM concentrations of less than 0.25 egm3, in both 2010 and 2020, but more substantial improvements for a large percentage of the population, including improvements in excess of 2 egm3 for more than 24 million individuals by 2020. 