if (document.images) {

    img1on = new Image();          
    img1on.src = "http://www.airqualitypartnership.org/img/2006/scale.gif";
   
    img1off = new Image();          
    img1off.src = "http://www.airqualitypartnership.org/img/2006/scale_spanish.gif";
	
	}

	// Function to 'activate' images.
	function imgOn(imgName) {
        if (document.images) {
            document[imgName].src = eval(imgName + "on.src");
	        }
	}

	// Function to 'deactivate' images.
	function imgOff(imgName) {
        if (document.images) {
            document[imgName].src = eval(imgName + "off.src");
	    }
	}