Hi there, When handling concrete, what we worry about is silica dust, which typically causes lung disease with long term accumulated exposure. The effects are delayed for months to years, and don t usually cause acute headaches like the one you are experiencing. Is it possible that you were exposed to other things as well while working there, like organic solvents in adhesives, which is way more likely to cause headaches? Other possibilities are simply dehydration, or heat stress. If you work with concrete regularly, I would advise you to be a lot more careful with your mask, because like I said the effects of silica inhalation often does not show until years later. You could develop silicosis, or lung cancer, and once that happens, the damage is irreversible. Make sure you change your clothes before you get home, or at the very least remove your outer clothing so that you do not bring the dust into your home. Hope this helps, and all the best to you. Regards, Dr. Teh