Does intentionally inhaling car exhaust fumes while running and breathing through the mouth invalidate the fast?

There is no harm in walking on a road with cars, and inhaling their smoke does not invalidate the fast. Road dust and smoke do not break the fast by agreement. It is stated in Al-Rawdh with its commentary: "Or if a fly, or dust from the road, or flour, or smoke enters his throat, he does not break his fast by consensus, just like a sleeping person into whose throat something enters." Likewise, scholars have unanimously agreed that if dust, smoke, flies, or bugs enter the throat of a fasting person, it does not invalidate his fast.