How to convert CAMS <2,5 µm (PM2,5) data from kg/m2/s to µg m -3

Hello, I ask for help to convert pm2.5 emission values which are in kgm-2s-1 to µg m -3.

Resolution is 0.1x0.1, daily data.

I tried at first to multiply by the number of seconds in a month and the area of a cell of 0.1 degree which is 11 * 11km2, 3600 * 24 *11*11*1000000/1000= 313*10^9 T/year.grid .

But I can't get to the density of the pollutant, that is, transforming it from mass to concentration.