Car exhausts release a variety of atmospheric pollutants, but one of the pollutants that is not released by car exhausts is magnesium oxide.

Magnesium oxide, or MgO, is not released by car exhausts due to the fact that it is not a component of gasoline or diesel fuels. It is a compound that is formed when magnesium is burned in the presence of oxygen, but since magnesium is not present in car fuels, magnesium oxide does not form during the combustion process.

Car exhausts primarily release pollutants such as carbon dioxide (CO2), carbon monoxide (CO), nitrogen oxides (NOx), sulfur dioxide (SO2), particulate matter (PM), and various volatile organic compounds (VOCs). These pollutants are formed as a result of the combustion of fossil fuels in car engines.

Carbon dioxide (CO2) is a greenhouse gas that is released when carbon-based fuels are burned. It is a major contributor to climate change.

Carbon monoxide (CO) is a colorless and odorless gas that is produced when carbon-based fuels are burned incompletely. It is a poisonous gas that can be harmful to human health when inhaled in high concentrations.

Lead oxide (PbO) is a compound that used to be a major component of gasoline additives, specifically tetraethyl lead, which was used as an anti-knock agent. However, the use of leaded gasoline has been phased out in many countries due to its harmful effects on human health and the environment.

In summary, while car exhausts release a variety of atmospheric pollutants such as carbon dioxide, carbon monoxide, nitrogen oxides, sulfur dioxide, particulate matter, and volatile organic compounds, magnesium oxide is not released by car exhausts as it is not a component of car fuels.