Question

How is ozone both beneficial and damaging?how we can prevent the damaging effect of ozone?

Answer 1

benefits of ozone ...
it prevents harmful sunrays to come in the atmosphere which causes cancer in humans
damages of ozone ...
it is harmful for humans if a human breaths it in the human will die

Answer 2

Ozone is a protective layer round our atmosphere that protects us from the harmful ultra-violet radiations coming from the sun.    

Harmful effect of ozone:

But this ozone layer is as dangerous as it is beneficial to us. When ozone layer is formed around the atmosphere, the gases release from vehicles combine with this ozone layer and become more dangerous for plants as well as animals.

How to protect from ozone damage:

We can protect our self  from the damaging effect of ozone by reducing the use of vehicles. The gases emit from factories and mills are also contributing to it, so we have to reduce their use as well.