No one nose but...

There's some clever science to how air- fresheners work. See how the scent is made to linger, and why combinations that might seem odd exist simply to get the job done

- Swetha Sivakumar

What does it take to make a room smell good?

Air-fresheners may seem simple enough: a perfume that spreads across a space, via aerosol, slow-release tablet or plugin diffuser.

They do rely on some clever science to get the job done, though. A particularly tricky aspect is controlling the scent-release curve. At their core, all air-fresheners revolve around volatile organic compounds, tiny scent molecules that are infused into a base and evaporate into the air when released.

How long we can smell a volatile compound depends largely on its chemical structure. Some evaporate in seconds (typically, small, light molecules such as those released by citrus produce). Others last minutes or hours (heavier molecules such as those from wood, musk or vanilla).