During the discussion on the AQI, it became clear that the index can capture only the short-term health effects of a few pollutants. But that leaves out the long-term health risk assessment of these pollutants and a host of other toxic pollutants like benzene and polycyclic aromatic hydrocarbons (PAH) whose shortterm health effects are yet to be identified. Moreover, these affect a larger section of people in addition to increasing problems of the more vulnerable sections of the population and the effects can be even more severe.

To deal with these chronic effects, Kirk Smith suggested the creation of a Chronic Pollutants Index (CPI). According to him, the cpi should be structured somewhat like the daily aqi, but would rely on annual average levels of pollution. It would not be reported on a daily basis, but updated quarterly with a rolling annual average. This can further be developed into a Cancer Pollutant Index, which will be able to show the cancer risk from exposure to the ambient concentrations of pollutants like benzene and PAHs.