In 1990, the United Nations (UN) presented the Human Development Index (HDI) as a measure of human development that considers three fundamental dimensions: a long and healthy life, being knowledgeable, and having a decent standard of living. This paper proposes some considerations about human well-being factors based on HDI analysis, also introducing some considerations on environmental pollution. As regards environmental issues, two different pollutants are considered together with their environmental costs: (i) greenhouse gas (GHG) emissions, which have an impact on a global scale, and (ii) emissions from fine particulate matter, primarily having an impact on a local scale. Thus, a new index based on the external environmental costs is proposed, and two scenarios are discussed. On the other hand, as it concerns human well-being, the results of surveys among the population are used. Furthermore, other features regarding health services and demographic aspects are taken into account, too. Italy is analysed as a case study over the last three decades. Easterlin’s considerations are verified based on the variation of perceived well-being related to the changes in GDP. The Italian case study shows that despite having achieved a satisfactory HDI level, there is a wide margin for improvement from both the environmental and the well-being standpoints.