Chapter 13 427 Table 3. Current CARB Volatile Organic Compound regulation for hair care products. Note: the Gel category last updated in 1994 is now part of the Hair Styling Product category. Product Category Effective Date VOC Standard (wt%) Hair mousse 1/1/94 16 12/31/02 6 Hair Shine 1/1/2005 55 Hair Spray 1/1/93 80 6/1/99 55 Hair Styling Gel 1/1/94 6 Hair Styling Product Aerosol and Pump Sprays 12/31/06 6 All other Forms 12/31/06 2 Current regulatory constraints focus primarily on VOCs, which are of particular concern due to their reactivity in the lower atmosphere (troposphere) along with nitrogen oxides to form ozone and the resultant contribution to smog creation. This should not be mistaken as the ozone necessary to filter UV radiation from the earth in the upper atmosphere (stratosphere). Additionally, VOC limits are currently mass-based, which means that all of the applicable compounds are treated equally regardless of their reactivity in the atmosphere. For example in a 55% VOC hairspray, 55 weight % of the formula can be comprised of VOCs. The individual ingredients contributing to this amount are irrelevant as long as the mass requirement is adhered to. An alternate way of measuring VOC content is by using a reactivity based approach which takes into consideration the photochemical reactivity of specific compounds and their potential to form ozone 16 this method weighs ingredients on reactivity rather than mass. It has been implemented by CARB in industries, such as aerosol coatings, as the Maximum Incremental Reactivity (MIR) scale. Another atmospheric environmental factor is Global Warming Potential (GWP), the measure of how much heat is trapped by