This letter is one of the latest research reports from IEEE TIV's Decentralized and Hybrid Workshops (DHW) on Ethics, Responsibility, and Sustainability (ERS). In the last year, we organized 1 distributed/decentralized and hybrid symposia (DHS), 2 DHWs, and 7 seminars. The following is a brief review of the findings from our DHS, DHWs, and Seminars, in particularly about a novel emission regulatory framework for intelligent transportation systems (ITS) and smart cities (SCs) in ERS. Vehicle emissions are one of the main anthropogenic contributors to global warming and atmospheric pollution. However, effective regulation of transportation emissions is still challenging, even in intelligent transportation systems and smart cities. To realize accurate estimations and credible predictions, a parallel framework is proposed in this letter, consisting of a parallel transportation level and a parallel vehicle level. Through low-cost computational experiments and parallel executions, both accurate estimation and emissionaware optimal planning can be achieved. Unlike previous emission models, modern aftertreatment systems (ATS) are considered as a core module in this novel modular integration model (MIM). An application case on $\mathrm{CO}_{2}$ emissions is conducted to validate the fundamental function of this framework. Compared with two well-known models, MIM shows better performance than two baselines, and the relative errors are below 4% even with unknown engine states.