Ozone is a gas that forms the lower layer of the Earth's atmosphere and is often described as having a clean, chlorine-like, yet burned smell. While it can be dangerous in high concentrations, ozone is also a very useful gas. It is widely believed that any natural smell of freshness is ozone. Some people think of ozone as the scent that fills the air immediately after a heavy rain or thunderstorm.
The odor of ozone has been described as partly reminiscent of chlorine, metal or burnt wire. It is likely that you have experienced the smell of ozone produced by lightning before. Have you ever noticed that clean, fresh smell before a spring rain? That's ozone. Even when there are hardly any lightning flashes, there are still traces of ozone and nitrogen dioxide produced by lightning in the air scattered around the storm. When the gust front of a storm blows it out before the rain, you can smell it before it “creeps” to the ground.
The human nose can detect ozone concentrations as low as 10 parts per billion. That's equivalent to three teaspoons of water in an Olympic swimming pool. You can also smell it when washing clothes. Those tiny static sparks between the clothes that come out of the dryer act like miniature lightning and produce just enough ozone for you to smell. There are air purifiers that intentionally produce ozone, which supposedly deodorize, disinfect and remove dangerous particles from the air in your home.
However, there are still devices that disinfect the air without releasing ozone into the room.
