I remember a few years ago, whilst working on building sites, smack very common(usually with roofers or cladder's, going high up, used to see them go into Toilet blocks and there'd be burned silver foil about, i presume it smack unless something else u need to do that with? Also painter's r always smoked up. The best/fastest block layer i ever saw always had a spliff hanging out of his mouth! Also lots of 360 machine drivers were shaky till they had there 4 cans of stongbow at 10 o'clock brew, and a couple more at dinner. Much less common these days, H and S keep an eye on it better! In saying that though i remember a couple of years ago a Health and Safety trainer came to our site on a Sat morning, turned up 3/4 hour late stinking of booze and gave us training, needless to to i found out a few months later he'd had his Liscence's taken away, Driving/ H and S!