Système Multi-Agents prédictifs pour la simulation de la pollution due à la production et consommation énergétique 

Système Multi-Agents prédictifs pour la simulation de la pollution due à la production et consommation
énergétique 

Air pollution

Air is defined as the odourless, colourless and invisible gaseous fluid that makes up the atmosphere and that the living things breathe. It is generally associated with the troposphere, which is the lowest atmospheric layer and closest to the earth (8 to 15 km altitude), however pollutants that have a long lifespan can reach the stratosphere (15 to 50 km altitude). Therefore, the air is sensitive to being influenced by human activities and natural phenomena such as photosynthesis in plants and evaporation from the oceans.

Chemical composition of air

The Earth’s atmosphere, or simply air, is a mixture of different gaseous substances and of varying concentrations. The gravitational field of the earth retains these particles around the earth. 10 Chapitre 2. Air pollution modelling The main gases that make up air are molecular nitrogen (N2) as well as dioxygen (O2), and traces of rare gases such as krypton, helium, etc. These gases are found in the air with identical concentrations regardless of location and up to an altitude of 100 km, because beyond this height there is hardly more air. The air also contains water vapour in varying concentrations depending on location and weather parameters. 

Structure of the atmosphere

The atmosphere consists of several layers, each layer has its own characteristics, the boundaries of each of its layers have been determined according to the discontinuity in the temperature variations. Therefore, the atmosphere is divided into five main layers:  • The troposphere: The atmospheric layer closest to the surface (8 to 15 km altitude), this layer contains 80 to 90% of the total mass of the air and almost all of the water vapour, in this layer meteorological phenomena occur (such as rain, clouds, etc.), and the temperature decreases depending on the altitude. • The stratosphere: up to 50 km, in this layer the temperature increases depending on the altitude up to 0°C, it includes the ozone layer. • The mesosphere: up to 80 kilometres, the temperature drops to -80°C, this is where most meteorites burn off on entering the atmosphere. • The thermosphere: up to 150 Km, it is characterized by the increase in temperature which can reach 1,700°C, and the very low pressure. • The exosphere: it’s a thin volume similar to the atmosphere and surrounds the earth, it’s where the atmosphere merges with the interplanetary space, it’s consists mostly of helium and hydrogen. 

Air Pollution

(Barker et al. 1963) describes the atmospheric (or air) pollution as the alteration of the chemical composition of the air, by increasing the concentration of certain substances (chemical or solid), this alteration lasts for a certain period of time to create toxic effects, and which will also have harmful effects on the ecosystem and health. The chemical composition of the air has been constantly evolving for thousands of years, these changes are due to disturbances of natural origin: Geological such as volcanic eruptions, Astronomical such as collisions with meteorites, or even biological (pollen, natural decomposition). Over the past 300 12  years, human activities have been causing more and more disruption for a relatively short period of time. Pollution can be local (on a regional scale such as: ozone peaks, smog), or global on a planetary scale (the greenhouse effect, destruction of the ozone layer). Pollution affecting the tropospheric layer is the most important type, as it is in this layer that humans and most species live. Other types of pollution may be considered as less important, except those that influence the climate, such as greenhouse gases, the latter affect the thermosphere layer. Air pollution is closely linked to other types of pollution, as the clouds of pollutants are transformed and participate in the increase of the phenomenon of acid rain. These rains transform pollutants and spread them in other forms: aquatic pollution, soil contamination and pollution, etc. 

Types of pollutants

The main air pollutants are divided into two very distinct large categories: primary pollutants and secondary pollutants.

The Primary Pollutants Primary pollutants are emitted directly from pollution sources such as road traffic, industries activity, heating, energy production and consumption, etc. For example (SEPA 2021): Sulfur oxides (SOx): SOx is a pollutant produced by many industrials and processed by volcanos, it’s mainly found in petroleum and coal, therefore its linked to the production and combustion of these energy sources, its most known for is the Sulfur dioxide (SO2). SO2 also is caused by some other industrial processes such as steel making and fertiliser manufacturing, and can be caused by natural sources as well, for instance geothermal activity. This pollutant causes respiratory issues such as bronchitis and asthma attacks, as long as irritating nose, throat and lungs, and it has been linked to cardiovascular disease. Carbon monoxide (CO): This toxic pollutant is an odourless and colourless gas, it results from the combustion of coal, natural gas, and wood, in addition to road traffic where studies showed that it is responsible of more than half of the emitted CO into the atmosphere. CO is a very dangerous gas, as it attaches to haemoglobin’s molecules in the blood, therefore it reduces the amount of oxygen that the body receives. The exposure to low amounts of CO makes you feel weak, dizzy, and disoriented, in the other hand, the exposure to high amounts of CO can lead to serious health problems from loss of conscious to death. Carbon dioxide (CO2): CO2 is known to be the most significant pollutant among the others, as it is speedily produced and emitted by different sources, and it’s more harmful to the climate than the others which led it to be called the worst climate pollution. Naturally, (CO2) exists with and immense quantity in the atmosphere and it’s essential for plants, however, recently it’s concentrations in the atmosphere increased greatly from 280 parts per million (ppm) in the pre-industrial era to 410 ppm. Its main source is the combustion of fossil fuels. Nitrogen oxides (NOx): Its main form is Nitrogen dioxide (NO2), it is a chemical toxic gas and it’s char-  Air pollution modelling acterizes by a biting and sharp odour. NOx results from the of oxygen and nitrogen gases in the air during combustion at high temperatures, therefore it results from the human activities such as combustion of fossil fuels, its natural sources include volcanos, lightning, and bacteria. NOx main effect on the human health is on the respiratory system, it can aggravate asthma, and lower the lungs function and decrease their defence which makes them more vulnerable against bacteria and infections. Ammonia (NH3): NH3 is a compound of hydrogen and nitrogen, it’s a colourless gas with a pungent odour. Ammonia is classified as a hazardous pollutant, and its sources include both natural and anthropogenic sources. Ammonia can cause a decrease in the biodiversity of the ecosystems, and can cause dangerous complications to humans when it’s inhaled such as burning the nose and throat, respiratory distress, bronchiolar . . . etc. Particulate matter (PM): The term PM refers to the liquid or solid particles suspended in air, their source can be either from human activities such as fossil fuel combustion and power plants, or they can be originated from natural sources, such as forest fires, volcanos, dust storms, etc. PM are classified according to their diameter as they vary greatly in size, particles with diameters less than 10 micrometre can penetrate into our noses and lungs and cause a lot of health issues, for instance, PM2.5 and PM1 generally have slower sedimentation rates and can therefore remain suspended in the atmosphere for days or even weeks. Consequently, these particles can be transported over long distances and undergo physicochemical transformations. Inhaling these particles can aggravate bronchitis and asthma, they can also irritate the eyes, throat, and lungs.  Volatile organic compounds (VOCs): These pollutants are categorized into two categories, methane and non-methane parts. Methane (CH4) plays a major role in causing global warming, while the non-methane parts (NMVOCs), xylene, benzene, and toluene are suspected to cause cancer such as leukaemia.

The secondary pollutants

The secondary pollutants are not emitted directly from pollution sources; instead, they are formed in the atmosphere from different compounds. For example (SEPA 2021): Ozone (O3): O3 exists in two different parts of the atmosphere and its effects depends on where it is situated, in the higher level of the atmosphere (the stratosphere) it produces naturally and it plays a vital role in that layer, because it protects the earth from the ultraviolet rays coming from the sun which damages the health, thus, this layer is often referred to by the ozone layer. However, the lower layers of the atmosphere and on the earth’s surface, O3 is formed through photochemical reactions between other pollutants such as the reaction between VOC and NOx, and it can damage our health by causing cardiovascular and respiratory diseases, and affect the performances of lungs. Peroxyacyl nitrates (PANs): PANs are a secondary pollutant as they form through photochemical reactions, and can cause respiratory problems and diseases. Under cold weather (< -20) PANs can stay in the atmosphere for up to three months, while in the warm weather they persist only for few hours. PANs decomposition can generate several types of other dangerous chemicals including CO2 and CO.  Sulfuric acid (H2SO4): H2SO4 is a very corrosive chemical that can exist as droplets or particles in the atmosphere, and it dissolves when exposed to water. Its main sources in the industrial that produce it or use it during the production such as oil refiners, metal smelters, and phosphate fertilizer producers, and it can be produced from natural sources such as volcanos. This pollutant can severely burn the eyes and skin, it can cause blindness and third degree burns on contact. Nitric acid (HNO3): This pollutant is rarely found in nature in its gas form, however it is produced mainly from traffic emissions, like sulfuric acid, it’s a corrosive chemical that can lead to irritating eyes, throats, and lungs, and can cause sever skin burns.