Consider Reuven, who takes an airborne virus (however he got it) and sticks it in Shimon's air vent. As Shimon is continuously exposed to this virus, he becomes progressively sicker.
What is Reuven's liability here (if Shimon survives, for damages, doctors' bills, etc.; if Shimon dies, for the death penalty)? Is he considered a direct damager? Or perhaps this is indirect, as Reuven isn't directly injecting the virus into Shimon, but rather leaving it for Shimon to inhale?