dust in throat while fasting

Assalamu Alaikum I have had this problem for a long time while fasting. For some reason I feel dust in my throat everyday I fast and I think it may be from my clothes or just from the air. As this is not done intentionally I would like to know if when it is in my throat and I can't spit it out am I allowed to still swallow my saliva from my mouth as I can't get the dust out of my throat.