Certain car-related regulations can help in the maintenance of air cleanliness.
The first type of car regulations that can help in the maintenance of air cleanliness is the one where limits are put on the ages of cars allowed on the roads. This is the scheme we have seen, where vehicles that are, say, beyond 8 years of age are banned from the roads. For this to be effective, it may have to be extended to all types of vehicles, and not just private cars. For instance, even the prison buses that are typically used for inmate transportation either in the public or privatized jails may have to be subjected to this age rule.
The second type of car regulations that can help in the maintenance of air cleanliness is the one where people who drive smoke-spewing vehicles are arrested and prosecuted. This can go a long way, for even brand new vehicles that are not well maintained can end up spewing a lot of smoke, and interfering with air cleanliness in a manner that well maintained but old vehicles couldn’t. So it doesn’t make sense to ban old vehicle, but allow ill-maintained (and hence smoke spewing) vehicles to continue messing up with air cleanliness. And it doesn’t have to be a question of selecting one of the two measures: both can be enforced at the same time.