1. lead
2. tropospheric ozone
Explanation:
1. A gasoline engine mixes the air with a small amount of gasoline, is compressed, and detonated with a small spark. The more the mixture is compressed, the more power is achieved, but if the mixture is compressed too much it detonates alone, the piston trips and effectiveness is lost.
Therefore, it was decided to incorporate an antidetonating additive to gasoline, thus allowing greater compression and preventing the mixture from detonating alone. These additives (Pb (CH3) 4) originally contained lead.
With the passage of time it was discovered that this solution was not the most appropriate. On the one hand there was the problem that this lead containing gasoline is expelled through the exhaust pipe with the rest of the gases, and this pollutes the environment, and on the other hand the lead also "poisoned" and rendered catalysts useless, when these began to be used.
These emissions generated the most important source of lead contamination.
To resolve this situation (eliminating the emission of lead, and being able to continue applying catalysts to reduce the impact of the other substances expelled) around the 1980s, it was necessary to develop new types of fuels, using other types of lead-free anti-knock additives, such as methyl t-butyl ether (MTBE). This was the origin of unleaded gasoline.
2.Tropospheric ozone (not to be confused with the stratospheric, whose layer protects the Earth from solar radiation) is a secondary pollutant, that is, it is produced from other pollutants emitted by cars or industry and, in addition, several kilometers where they occur
Its effects on health depends on your level of concentration. From 180 micrograms per cubic meter (the level of information), certain people - especially asthmatics and those with respiratory problems - could see their ailments increased.
