Plants
According to a Science Daily article published in October 2010, scientists have recently discovered that plants clean the environment even better than we thought. In fact, plants, especially deciduous trees, absorb oxygenated volatile organic compounds (oVOCs) at a rate that is four times faster than previously estimated. Some oVOCs would otherwise morph into aerosols and have adverse effects on human health. Plants take in these chemicals in times of stress and transform them into helpful enzymes.
Ozone
The ozone layer is made up of hydroxyl radicals. These radicals are especially helpful for cleansing because they have an extra electron which makes them more likely to pair up with other, dangerous chemicals in the air and convert them into benign chemicals. Hydroxyl radicals remove poisonous substances like hydrocarbons and carbon monoxide.
Sea Salt
Sea salt that sprays into the air forms raindrops by attracting water that collects around bits of pollution floating in the air. Air pollution typically stops clouds from releasing precipitation, but over large bodies of saltwater, the sea salt forms its own rain using the pollution and overrides its harmful effects.