I have no scientific proof as to the cause. Notwithstanding, there are reasonable grounds to assume that fireworks were probably responsible for the increase in PM 10. I have never seen PM 10 to increase significantly without PM 2.5 and PM 1.0 reacting similarly. By the end of the morning the 3 PM values were more or less harmonising. I agree that this is theoretical, but, at least, it is an explanation of the observed phenomena