Electrodes are made from one or two parts according to their different types. Electrodes are used in arc welding. There are two types of arc welding: Shielded Metal Arc Welding (SMAW) and Gas Metal Arc Welding (GMAW). We have two kinds of GMAW which are TIG (Tungsten Inert Gas) and MIG (Metal Inert Gas)/MAG (Metal Active Gas). In MIG/MAG, there is no electrode in use, and fillers weld the base metals. But in TIG, there is a tungsten electrode which is a non-consumable electrode and remains static and intact during welding. This electrode is pure with 1 to 4 percent impurity. This electrode is made of tungsten because this element has the highest melting point. 
Electrodes that are used in SMAW are different from tungsten electrodes. These electrodes consist of two parts: cored wire and flux. The difference in cored wires and flux makes varied electrodes. The cored wires should be the same as base metals. They make up welding. Flux has many roles in welding. The primary function of flux in welding is to oxidize the base. Then it can help the molten metal stay in the considered place. Flux can speed down the freezing phase of molten. It can also stabilize and fix the arc, control the viscosity of welding metal, etc. There are four kinds of flux: 1) Cellulose flux, 2) Rutile flux, 3) Acidic flux, and 4) Alkaline flux. At the end of the electrode, there is a bare part of the cored wire that is for attaching to the welding handle and electrical connection.
Welding Electrode Selection
To have a suitable and correct selection among welding electrodes, many factors can help us step forward. A number has been printed on the flux of electrodes, which is the standard number. This standard number may be according to the American Welding Society (AWS). Standard Welding Procedure Specifications (SWPS) provide codes that help welders indicate different welding consumables. E7018 is an example of the standard number for electrodes. “E” stands for “Electrode”. 
In this example, two first digits, which is 70, are the tensile of an electrode in kilo pound per square inch (KPI). The third number is the welding position, which is flat, horizontal, vertical, and overhead. The fourth number is the type of coating and current. We can detect our suitable and proper welding product according to these standard numbers. To adjust our needs and proper electrode, we should know the combination of the base metal. For example, E6013 is suitable for steel, and we cannot use it for cast iron. Then we should analyze the welding position. After that, we should detect the importance and the usage of welding of separated base metals. Finally, the welding penetration rate should be measured. Sometimes we find our proper electrode, but maybe the welder is not professional enough to weld with that electrode. For instance, E6013 is an easy electrode for welding, but E6010 is not easy enough to be used by an armature and inexperienced welder because it has a penetrative arc. So, that can be an essential parameter for selecting the proper electrode.
Welding Effects on Health
Welding has some harmful effects on our bodies and health. Rays, noises, fumes, and body position during welding are the main reasons for harm. The rays ascending from welding are UV and IR. These rays are because of the melting metals during the welding process. They affect our eyes and skin. Tearing, reddening, swelling, and itchy eyes are the primary side effects of welding. After a long time, cataracts can appear. A cataract is a disease that causes the eyes’ lenses to become white, and if treatment is denied, the sight can be lost. To prevent these effects, we should use some welding helmets and goggles. Our skin is in danger as well. Welding and the UV cause burning, inflammation, and blister on your skin. For the long-term duration, skin cancer can appear. To prevent these effects, we should wear sunscreen. After the eyes, the welder’s ears are under effect. Welders may hear the hissing sound, or hearing loss may occur. Some earplugs can protect your ears from these effects. 
Welding fumes contain many toxic gases and poisonous substances that can smell easily. One of them is hydrogen sulfide. It is the result of carbide burning. These dangerous substances can go through your lungs’ airbags and cause coughs, headaches, dizziness, digestive disorders, anesthesia, and sometimes respiratory failure and death. Wearing welding masks with new disposable air filters and good air conditioning in the workshop can decrease these health hazards. Welders should have periodic health examinations to have early detection and treatment.
Welding Effects on Environment and Global Warming
Next to the harmful and hazardous effects of welding on welders’ health, we should be aware of its environmental risks and relation to global warming. Welding fumes contain many toxic gases such as CO, O3, and NO2 and particulate pollutants such as FeO2, F-, NiO, and ThO2. Some of these substances result from the welding, but some are because of UV ascending, like O3. These harmful effects are on the air and ozone layers. 
AS Co2 and Ar are cheaper and more available, they are used as shielding gas in welding. These gases are some greenhouse gases and the leading cause of global warming, so we should decrease using them. Nowadays, welders and welding associations try to use harmless gases to reduce oxidation and these dangerous effects. Not only these gases are harmful, but also flames and heat can affect global warming. They are thermal energy and will be freed and moved into the air and our environment. Some welding processes need chemical and natural materials such as water to cool base metals and welding systems and some greasy materials to improve welding quality. These materials harm nature. The energy source of arc welding is electricity. High voltage and amperage are needed, and supplying these factors directly harms our nature and causes global warming. Choosing high-quality welding products and consumables can decrease these needs and side effects. Welders and companies should select the best way and standardize the welding process and procedures to reduce these harmful effects on our environment.