Tires are hydrocarbon composite articles which not subjected to spontaneous combustions. However when ignited in open air, they release potentially hazardous levels of carbon monoxide, mono and poly aromatic hydrocarbon and various other decomposition after burning. A wide variety of decomposition products after combustion are:
i. Ash containing carbon, zinc oxide, titanium dioxide and silicon dioxides.
ii. Sulfur compounds (carbon disulfide, sulfur dioxide, hydrogen sulphide).
iii. Polynuclear aromatic hydrocarbons that usually detected in oil runoff such as benzo (a) pyrene, chrysene and benzo (a) antharacene.
iv. Aromatic, naphthenic and paraffinic oils
v. Oxides of carbon and nitrogen
vii. Various light-end aromatic hydrocarbons such as toluene, xylene and benzene.
The secretion of disintegration due to uncontrolled fire combustions are varied and were governed by variety of factors including tire type, burn rate, pile size, ambient temperature and humidity.
Major environment impacts of tires uncontrolled combustion are concerning three vital elements that support living organism which are air, water and soil component. The pollutions of the elements mentioned are describes accordingly:
It is the pollutions due to the emission of carbon monoxide and other substances such as volatile organic compounds, dioxin and polycylic aromatic hydrocarbons that released into the atmosphere. The non-combustible components of tires contain a range of potentially toxic material that can be released to the atmosphere if tires are burned in an uncontrolled fashion. Emissions can include dioxins and furans which are carcinogenic as well as oxides of nitrogen and sulfur. Nevertheless, tire has lower overall greenhouse coefficient than coal.
The intense heat allows pyrolysis of the rubber to occur, resulting in an oily decomposition product which is manifested as an oil runoff. This runoff can be carried by water. Furthermore, other residues such as heavy metal can also be carried by water. This could be occurred during fire fighting and rainfall or surface runoff.
Residues that remain on site after combustion can cause two types of pollution that referred to immediate pollution of liquid composition product penetrating soil and gradual pollution from leaching of ash and unburned residues following rainfall or other water entry.
Due to the environmental hazard characteristics, more concerns raised to the negative impact of tires discarded in landfills. Therefore, it is critical to look into possible reusability of these wastages into other type of applications. There has been some work done on using tire waste for civil engineering application. The fact that tires are durable is one of the main advantages for their use. Provided that applications are appropriately and properly designed and engineered there should be no environmental liability. Therefore, further research on the long-term properties would be needed to establish the long-term performance of rubber materials in structures.