Hi Greetings. Ya you are right pimples mainly occur in oily skin and it increases with dirt, dust pollution etc. Environmental, lifestyle and dietary modifications also play a role in it. It is better to use a face wash having salicylic acid and do apply a water based sunscreen regularly. Do visit a qualified dermatologist near you for treatment and early resolution of pimples. Regards, Dr Anshul Jain, Nagpur.