Extended Data Fig. 1: Chemical structures of OPFR parent compounds and transformation products studied here.
From: Uncovering global-scale risks from commercial chemicals in air
a, Nine OPFR parent compounds. b, Ten OPFR transformation products identified in GAPS–MC field samples. TCEP-1 and TCPP-25 (see Supplementary Table 1) are difficult to distinguish from each other as they have identical chemical formulae. However, given that TCEP-1 and TCPP-25 are formed through one-step and two-step photooxidation reactions, respectively, and given that the oxidation timescales associated with urban regions are short23, TCEP-1 is likely to be the dominant product.
