Destroy Particles if they are outside their emitter

I want to destroy the particles which, when the emitter moves around particles float off into the distance.

This is what ive got so far but it dont work correctly (c#)

	void OnTriggerExit(Collider col)

you could also just use the trigger event in the particle system and have them killed if they leave a volume

I did something similar by destroying particles that are a certain distance from the emitter:

using System.Linq;
/// <summary>
/// Destroys particles that are farther than DistanceToDestroy from the particlesystem emitter
/// </summary>
public class ParticleMaxDistance : MonoBehaviour
    public float DistanceToDestroy;

    private ParticleSystem cachedSystem;
    private Vector3 staticPosition;

    void Start()
        cachedSystem = this.GetComponent<ParticleSystem>();
        staticPosition = this.transform.position;

    void Update()
        ParticleSystem.Particle[] ps = new ParticleSystem.Particle[cachedSystem.particleCount];

        // keep only particles that are within DistanceToDestroy
        var distanceParticles = ps.Where(p => Vector3.Distance(staticPosition, p.position) < DistanceToDestroy).ToArray();
        cachedSystem.SetParticles(distanceParticles, distanceParticles.Length);