La roche possay effaclar k la roche posay effaclar k research has shown that under the effects of external aggressors pollutant particles dust oily imperfection prone skin undergoes oxidation which can trigger a chain reaction 8211 hyper keratinisation sebum hyper production oxidation of sebum and impurities present at skin surface all of which can lead to the formation of new imperfections suitable for combination to oily imperfection prone skin also suitable for sensiti