Patent ID: 7820188

Claim:
A substrate that can actively dispense a volatile air treatment chemical upon being heated, the substrate comprising: granular sand particles adhered together to form a body having a network of pores; and volatile air treatment chemical disposed in the pores; wherein the substrate has a first end and a second opposed end; and wherein an average size of the granular particles adjacent the first end is sufficiently less than an average size of the granular particles adjacent the second end such that the first end tends to wick air treatment chemical towards the first end as air treatment chemical is dispensed from pores of first end; whereby the substrate is capable of delivering a first burst of the volatile air treatment chemical from the first end when the substrate is heated adjacent the first end, and wherein if thereafter the substrate is allowed to cool it is capable of delivering a second burst of the volatile air treatment chemical from the first end when the substrate is thereafter heated for a second time adjacent the first end, the second burst comprising at least in part volatile air treatment chemical that has been wicked towards the first end from elsewhere in the substrate; wherein the volatile air treatment chemical is an insect control agent which is selected from the group consisting of natural pyrethrins, pyrethrum extract, synthetic pyrethroids, and mixtures thereof; and wherein the granular particles comprise sand and a binder.