Dangerous and toxic substances must be covered or well fenced since the consequences of falling into them can be quite severe. Again, measures must be taken to avoid falls from high heights e.g. fencing of open sides of high floors on a building.
Apart from that, transparent and translucent doors, windows or walls should appropriately be marked to avoid accidents due to breakage or coming into contact with them because they are not easily recognizable. Proper construction of doors and gates is paramount and if necessary, safety devices should be fitted to them.