Health Bar fire damage

hi guys. i have a health bar script and i want to have a flame particle system to lower the bar. any suggestions?

below is the script:

using UnityEngine;

using System.Collections;

public class PlayerHealth : MonoBehaviour {
public int maxHealth = 100;
public int curHealth = 100;

public float healthBarLength;

// Use this for initialization
void Start () {
    healthBarLength = Screen.width / 2;
}

// Update is called once per frame
void Update () {
	AddjustCurrentHealth(0);
}

void OnGUI() {
	GUI.Box(new Rect(10 ,10, healthBarLength, 20), curHealth + "/" + maxHealth);
}

public void AddjustCurrentHealth(int adj) {
	curHealth += adj;
	
	if(curHealth < 0)
		curHealth = 0;
	
	if(curHealth > maxHealth)
		curHealth = maxHealth;
	
	if(maxHealth < 1)
		maxHealth = 1;
	
	healthBarLength = (Screen.width / 2) * (curHealth / (float)maxHealth);
}

}

Create a cube and take off the mesh renderer. Place the box around the particle system and set it to isTrigger.
Tell a script on the cube to damage your health when you are inside the trigger