from telegraph.co.uk: As more cities in America legalise the drug, attention has switched to the pungent smell that wafts from the joint itself. Denver has passed a new “odour ordinance” with a potential $2,000 (£1,247) fine for anyone found guilty of polluting the atmosphere. The need to draw up standards emerged because of the confusion over the legal position of whether somebody smoking marijuana in their own home could be committing an environmental offence when the smell seeps into the street. Under the new law an offence is committed if the odour is detectable when the smoke is mixed with seven times the volume of clean air. The nose telescope – also known as an olfactometer – is the device used to measure the concentration of cannabis in the air.