Cryogen spray cooling (CSC) is a method to cool and thus, protect the epidermis which is used with dermatologic laser therapy to decrease treatment pain, allow safe treatment of darker skin types, and safe use of high laser fluences .

CSC with Tetrafluoroethane has been incorporated into many Food and Drug Administration (FDA) approved, commercially available laser devices currently used for treatment of vascular lesions, hair removal and non-ablative skin rejuvenation.

A millisecond cryogen spurt is applied to the skin surface immediately before laser exposure. As liquid cryogen rapidly evaporates, the superficial skin temperature is reduced as a result of supplying the latent heat of vaporization.

Tetrafluoroethane, an environmentally compatible, non-toxic, non-flammable freon substitute, has been demonstrated in multiple studies to be a safe and effective cooling agent and is the only cryogenic compound currently approved for dermatologic use by the FDA.

The researcher' want to characterize the clinical cutaneous effects of varying spurt durations and spurt delivery patterns (single vs. multiple spurts) of CSC in Fitzpatrick skin types I-VI, that spurt durations of 100 ms or less will result in a very low incidence (less than 2%) of clinical skin effects (redness, blistering, local skin allergic reaction or skin discoloration) in any skin type. The number of subjects developing each type of skin response (erythema, blistering, hyperpigmentation, hypopigmentation, scarring, or other) will be reported for each cryogen spurt duration or spurt regimen and each skin type.

Inclusion Criteria:

• Adult 18 years and older

Exclusion Criteria:

• Age <18
• History of cold sensitivity
• Inflammatory rash on the test site