Which among the following elements (metals) pollutes the air of a city having large number of automobiles?

Lead is the primary metal pollutant associated with urban air in cities with high automobile density. Historically, the most significant source of lead in ambient air was the exhaust from motor vehicles using leaded gasoline, where tetraethyl lead was added as an anti-knock agent [t1][t10]. Although leaded petrol has been phased out globally as of 2021 to prevent premature deaths, lead remains a persistent urban pollutant [t4]. It is still found in urban soils and can be resuspended into the air [t1]. Beyond fuel, lead is present in lead-acid batteries and is released through the wear and tear of vehicle components like brakes and tires [t5][c4]. In large cities, the concentration of suspended lead particles contributes significantly to the higher pollution levels compared to rural areas, causing severe health issues such as nervous system damage and respiratory problems [c2][c4].

Sources

1. [1] https://ww2.arb.ca.gov/resources/lead-and-health
2. [2] https://pmc.ncbi.nlm.nih.gov/articles/PMC8812512/
3. [3] https://www.unep.org/news-and-stories/press-release/era-leaded-petrol-over-eliminating-major-threat-human-and-planetary
4. [4] Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 17: Contemporary Issues > 1. Air Pollution > p. 38
5. [5] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > Lead > p. 64