Run OnParticleCollision every sec

I run a method in OnParticleCollision which reduces the volume of a factor. I want to remove this factor every second. Although, in OnParticleCollison the collisions are numerous and runs multiple times and very fast. Is there a way of catching it and run this reduction every second?

Code (CSharp):

1.    void OnParticleCollision(GameObject other)
2.    {
3.         factor -= reduction
4.  
5.    }
6.