In order to fully understand how catalytic converters are detrimental to our environment one must first know the overall construction of the catalytic converter. The catalytic converter is composed of a few precious earth metals like platinum, palladium and rhodium. Platinum’s use is for a reduction catalyst and in addition, an oxidation catalyst. Although a very active and widely used catalyst platinum is extremely expensive. Inside the catalytic converter, the rhodium that is present is used as a reduction catalyst, and the palladium that it is composed of as well is used as an oxidation catalyst in the complete reaction of the automotive catalytic converter. The mining of these precious metals are another crucial aspect to take in consideration when examining to what extent the environment is affected by catalytic converters. What makes these rare metals so hard and expensive to mine is the fact that the metals are not found on the surface of the earth but much farther down than other metals and are rarely found in extractable concentrations; thus what makes them so expensive and hard to find. The mining of these rare metals is not only expensive to do but is also extremely harmful to the environment. Some of the main environmental impacts of mining include: erosion, the formation of sinkholes, a large lack of biodiversity, and the contamination of soil and groundwater. In addition, the metals that are found in the catalytic converter like palladium and rhodium specifically cause dissolution of metals by runoff and groundwater while mining. The reason for these environmental effects is due to the fact that Palladium ore spawns below a depth of 1,100 feet and thus take much longer to mine than other metals. Another aspect to consider of environmental harm from mining is how much fossil fuels are burnt while trying to mine these rare metals. In the last 5 years Russia alone has mined 82 metric tons of palladium at a price of $690 (USD) per ounce (in 2015), which equates to $1.996 billion (USD) in those 5 years for palladium alone. In today’s world, palladium has skyrocketed to over $1,000 (USD) an ounce. This is the first time in 16 years that this rare earth metal has reached over $1,000 an ounce, and the believed cause of this vast increase in price is due to the high demand of palladium from the auto industries all over the world. Today, 80% of the palladium that is mined from the earth is used in catalytic converters alone. The Combustion Engine The combustion engine is an engine in which it generates mechanical power by combustion of a certain fuel. There are two types of combustion engines, internal and external combustion engines. For this topic the focus is on the internal combustion engine, which take high pressure and high temperature gases that produce combustion and this combustion applies force on the piston inside the engine and this force moves the piston over a distance and thus transfers chemical energy into productful mechanical energy. In the combustion reaction the gases that are present are: 70% nitrogen and 20% oxygen. However, when these two gases are combined together it creates a more harmful product NO (Nitrogen Monoxide). This reaction is N2 + O2 ? 2NO; also due to the fact that Nitrogen Monoxide has a high tendency to react with Oxygen the reaction is then converted to 2NO + O2 ? NO2 . The final aspect that is seen with combustion engines is how it takes a high octane fuel like gasoline, mixes with air and then causes the cylinder to move thus repeats the cycle about a thousand times per minute in order to propel the vehicle and set it in motion.Nitrogen Oxides Nitrogen oxides consist of a group of gases that have nitrogen and oxygen present; for example Nitrogen Monoxide and Nitrogen Dioxide. Nitrogen Monoxide also known as (NO) is one of the two large pollutants that are produced by the internal combustion motor. The second would be Nitrogen Dioxide which is also just as harmful to human health and society as well. Both types of pollutants are devastating to the environment regardless of the state they are found in. However a by product of these two is Nitrogen oxide (NOx) which is not harmful to health in small doses however when found in high concentration aspects it can cause  irritation and in the long run inflammation of the airways which can ultimately cause death. Nitrogen oxides are formed at two different stages in the combustion process, the first is from the reaction of oxygen with nitrogen compounds in the fuel, and the second is from the reaction of nitrogen with oxygen in the combustion air. This combination of nitrogen monoxide and nitrogen dioxide is one of the main forms of ozone layer depletion and detrimental harm to the environment as a whole. In 2012, 40% of nitrogen dioxide and nitrogen monoxide emissions came from motor vehicles and transportation. This vast emission of harmful Nitrogen oxides into the atmosphere can cause more than just health problems to humans but can cause negative effects on plant growth and health. in addition to this, NOx (Nitrogen Oxide) reacts with different pollutants in the air that combine with sunlight to form ozone that is low to the ground which causes damage to vegetation at higher concentrations.  Carbon Monoxide Carbon monoxide is a colourless, odorless, and poisonous gas that is manufactured when carbon is burnt with inadequate amounts of air. During combustion and or incomplete combustion, carbon dioxide is produced from the reaction. Higher concentrations of carbon monoxide can cause effects to the thought processes in the brain and complicate the health issue even more. This is due to carbon monoxide being a cumulative poison which can get into the bloodstream and body within minutes and cause severe brain damage or death. Carbon monoxide is much different than other pollutants and gases in that it can last up to a month in the atmosphere, and can be transferred long distances in the air as well. Although carbon monoxide is known to be a weaker greenhouse gas its harmful influences go farther beyond the direct effects of carbon monoxide. This unique gas has the ability to directly affect other harmful greenhouse gases like methane and carbon dioxide making their concentrations even stronger which ultimately causes even more damage to the environment. These dangerous greenhouse gases combined do even more damage to the ozone layer in the atmosphere which, again, is a major cause of global warming.History of the Catalytic ConverterAir pollution is not a recent issue, in fact in the late 1500’s during Shakespeare’s time, one of his plays speaks about the quality of the air in that day and age. In the early 1940’s and 1950’s the overall air quality in a vast number of towns and cities all around the world had been depleted so much so that an alternative solution had to been found and quickly. The main reason this depletion had been brought about was due to the large amount of smog and pollutant gases from combustion engines and motor vehicles as was earlier stated. In order to fight this devastating problem, the state of California in the mid 1970’s fitted all of their motor vehicles with catalytic converters. However this was in spite of a large resistance from the automotive industry due to the restricting factor of horsepower in a vehicle as well as the price of converters as well. This implantation slowly made its way into not only the rest of America, but across the world. The actual invention of the catalytic converter was made by a man named Eugene Houdry, a French mechanical engineer who was an expert in catalytic oil refining and lived in America around 1950. When the smog problems came about in Los Angeles in the mid 1900’s Houdry became increasingly concerned about the exhaust systems on automobiles and began to develop a solution to this economic problem. He originally began making catalytic converters for smoke stacks on industrial plants to reduce the harmful chemicals being released into the atmosphere and soon realized this same type of converter could be used on automobiles. This realization is what led him to the creation of the catalytic converter on gasoline engines and automobiles around 1950. His creation of the catalytic converter was soon taken over by a host of engineers from the E.P.A and refined to fit the automobile. However, his work did not go unnoticed, he was later awarded the United States Patent 2742437 for his accomplishments.In 1974 the Environmental Protection Agency required all vehicles manufactured in 1975 model years and on to have a catalytic converter implemented on the vehicle. The federal government actually added a few details to the converter in order to make it more efficient as a whole. These materials were a mixture of silica and alumina; this mixture is known as the “washcoat”. The actual core of the converter is specifically shaped for maximum flow and also maximum efficiency as well. This honeycomb shape allows the converter to catch more particles and redirect them back into the engine to be burnt up as well as allowing the motor to flow and breathe more efficiently. All of these intuitive designs are what make the catalytic converter so prominent in the diffusion of these harmful, environmentally destructive chemicals.  Controversy of the Catalytic Converter There is an enormous amount of controversy surrounding the catalytic converter and its implementation on automobiles around the world.  First is the overall effect of carbon dioxide on the environment and the harm it causes. Carbon dioxide, to some, is in fact considered a pollutant due to the fact that it meets the legal and encyclopedic definitions of a “pollutant”. In addition to this it is also considered a pollutant because it poses a serious threat to human health as well as being one of the most abundant greenhouse gases in the atmosphere. These greenhouse gases, including carbon dioxide, without a doubt fit the Clean Air Act’s definition of an air pollutant. However, on the contrary, people also would say that carbon dioxide is not an air pollutant at all. This is because it is believed that labelling carbon dioxide as a pollutant is a false statement due to the role it plays in the development  of life on earth. In addition to this, the Environmental Protection Agency explains how it does not classify carbon dioxide by itself as a pollutant due to the fact that all humans exhale this gas. To continue the argument that it is not a pollutant, carbon dioxide is also found in carbonated sodas and water that people drink every day. The final reason that some do not identify carbon dioxide as a harmful pollutant is because as humans we breathe in 400 parts per million and then exhale another 40,000 parts per million with absolutely no effects or illness.Another aspect of why the catalytic converter is a controversial idea is due to the actual converters problems and issues within it. The initial and main problem with the converter is that, especially in early years, the converter itself takes a while for it to reach a hot enough temperature to actual do its job and burn the fuel that was being sent through it unburnt. The second issue that many automotive companies found was that these vehicles would now burn 30% more fuel in order to capture any unburnt fuel that might have escaped the converter. In another view point the automotive companies saw this as wasting fuel in order to help support the converter to catch the wasted fuel. This issue also posed a new problem with car companies in that now the miles per gallon of the specific vehicle has just gone down by almost 30% due to these catalytic converters. The final concern that has its’ hand in the controversy is how expensive these catalytic converters are to manufacture and especially in a large quantity. As previously discussed, these converters are manufactured of very precious, rare, and expensive earth metals. This was seen as a huge set back for motor companies all across the world because of the implementation of the catalytic converter is causing them to spend millions of dollars a year more on these vehicles and the consumers not wanting to spend any more on automobiles than they already are.