Block heaters can help both ease of starting and reduce the amount of idling required to get an engine closer to operating temperature (closed loop), where Open Loop is the period where emissions are highest due to richer than stoichiometric Air:Fuel ratios.
Scuzmak t1_iur8oy2 wrote
Reply to 30 minutes of car preheating in sub-zero conditions produces as much particulate emissions as driving 97km in a gasoline car, or 20km in a diesel car “These findings do not suggest to stop preheating cars; instead, we could reduce the emissions by using similar methods that are in place for engine” by giuliomagnifico
Block heaters can help both ease of starting and reduce the amount of idling required to get an engine closer to operating temperature (closed loop), where Open Loop is the period where emissions are highest due to richer than stoichiometric Air:Fuel ratios.