Secondary – pollution that is formed from the chemical reactions of primary pollutants

Ozone is what is referred to as a 'secondary" pollutant'.

Ozone is what is referred to as a "secondary" pollutant.

Ozone is what is referred to as a 'secondary" pollutant'.

However, at ground level, ozone is a harmful secondary air pollutant.

Ozone is a secondary pollutant and is therefore not emitted directly into the air.

Ozone is a secondary pollutant, that means it is not emitted directly into the air.

� Ozone is the main component of smog, but it is not emitted directly into the air.

The method is advantageous in that it is free from the formation of a secondary pollutant.

It is a secondary pollutant, meaning that it is not directly emitted.

Ozone is a secondary pollutant, meaning that it’s not emitted directly by one source or another.

is environmentally responsible and contains no secondary contaminants such as solvents or grit media

It is environmentally friendly and contains no secondary contaminants such as solvents or grit.

Environmentally-friendly and contains no secondary contaminants such as solvents or grit

It's environmentally-friendly and contains no secondary contaminants such as solvents or grit media