When i was 11-12 yrs old i use to mess around with empty spray pint cans that only had the air but no paint. we would spray them at our face to make our hair go up after google searches im worried that i could have harmed my brain killing brain cell?

If you are not symptomatic, and otherwise we'll, there is likely no long term effect. Pulmonary function testing is indicated if you have respiratory symptoms. Watch for signs of shortness of breath, cough and other symptoms.

Eight to nine years later it is hoped you are past this stage. Yes you probably burned up some brain cells but if you function well in your daily life it was likely not enough to matter long term. Rather specific neuropsychologic testing might suggest the intensity of any related issue but if you are doing okay it is hardly worth looking into. You can't fix it if it happened.