Introduction
The purpose of impact analysis is to highlight the extent of environmental modifications that occur in the environment following releases (emissions or effluents) into the environment or from the consumption of resources by productive activities. This task is anything but simple, especially regarding the consequences of emissions in the environment due to objective problems of identification and scientific interpretation of the correlations between these emissions and environmental effects. The disciplines that study the effects of human activity on the environment are characterized by several difficulties, mainly related to the rigorous interpretation of these effects and the formulation of scientifically acceptable prediction models. Having made this necessary premise, it is clear what the main limitations of an environmental assessment according to the LCA methodology are. In the following paragraphs, we will further delve into the topic.
Some definitions
Before beginning the discussion proper, it is appropriate to recall some concepts in order to clarify the meaning of the terms that will be used in the text.
- Emission: Emission of harmful substances
- Transmission: Diffusion and possible transformation that substances undergo once introduced into the environment
- Introduction: Concentration or deposition of pollutants in the place of action
- Impact: Immediate physical result of a given process/activity stemming from the emission of certain substances into the environment.
Action scales
The consequences of substance emissions into the environment can occur in the immediate vicinity of the emission point or have an impact on the entire planet. In essence, environmental effects can be divided into global, regional, or local. Anticipating what we will see in the upcoming lessons, we can affirm that the following effects are:
- Ozone hole = Global
- Photochemical oxidants = Regional / Local
- Toxicity = Regional / Local
- Eutrophication = Regional
- Acidification = Regional
- Greenhouse effect = Global
- Area degradation = Local
- Resource consumption = Global
This aspect is mainly due to the physical and chemical characteristics of the emission that generates the effect. Example: CO2 emissions responsible for the greenhouse effect. Analyzing its behavior in the atmosphere and particularly its residence time, it is possible to classify the greenhouse effect as a global-scale effect because it has been established by the scientific community that emissions in one part of the planet contribute to the same effect on the entire planet. On the contrary, noise generation in a marble mine in Italy does not disturb European populations, nor can it be physically added to the noise produced by the factory producing semifinished steel products in Germany. Noise, therefore, is a local-scale effect.
Stressor Element
A stressor is defined as the set of conditions that can lead to an environmental impact. Example: Let's consider the total SO2 emissions resulting from an inventory analysis. Acid rain and the consequent acidification with possible biodiversity loss in a river are the most plausible immediate consequences. The emission of acidic substances represents the primary stressor, which can be associated with other groups of derived stressors such as those mentioned above, from acid rain or from biodiversity loss.
The final result of this phase will thus be an environmental profile of the analyzed system. The goal may also be to identify critical points in order to minimize the impacts due to processes.
Main environmental effects
In building impact categories, the following main paradigms are used: Ecology, health, resources, and social implications. Below are the corresponding environmental effects, with the related terminology in English in use.
Ecology: Effects on population and ecosystem (Ecological effects);
Health: Effects on human health and safety (human health and safety effects);
Resources: Depletion of resources, energy, and materials (resources depletion);
Social Implications: Impact on all human activities interacting with the analyzed system, resulting in habitat degradation.
Based on this classification, specific effects characterizing the various impact categories are selected, namely:
Greenhouse effect - Global warming
Thinning of the ozone layer - Stratospheric ozone depletion
Acidification - Acidification
Eutrophication - Nutrient enrichment
Formation of photochemical smog - Photosmog formation
Human and eco-toxicity - Human and eco-toxicity
As for raw materials and energy understood as resources, a criterion based on the concept of resource "non-renewability" is adopted:
Consumption of non-renewable resources (energy and materials) - Resources depletion
[Further insights on impact categories or go to Part VI b - Calculation method in-depth]
