First

♤ Pollution inventory and apportionment studies that assess relative contribution of different sources are looked at in isolation and not within a coherent framework of health protection.

♤ What ultimately should drive policy is not just what source is emitting more but which source is likely to lead to a greater exposure to health damaging pollutants.

♤ Globally, studies show vehicles contribute from a quarter to close to half of the particulates in cities.