In the real life, there are a wide variety of very ordinary daily driving situations that have an effect on the combustion chamber’s operating temperature, usually requiring "hotter" or "colder" spark plugs, than the original stock. These conditions may be:

• Driving or traffic conditions,
• Operating conditions,
• Engine wear,
• Fuel qualities,
• Weather conditions,
• Use of LPG, natural or propane gas as fuel,
• High Performance modifications

Moreover, these conditions may combine in endless ways.

Almost no one was aware that although the air/fuel ratio was correct, the polluting emissions could dangerously increase if the stock spark plugs used result hotter or colder than needed due to the mentioned conditions. So it is more likely that you are having Heat Range problems -even if you didn't know they existed.

This is a serius warning from the “Environmental Health Center” (EHC) a Division of the National Safety Council (NSC): “malfunctioning vehicles, can release as much as 10 times the emissions of well maintained ones."

The research team of the Spark Plug Heat Range DETERMINATOR stablishes that:

If a spark plug is colder than necessary.

The Combustion chamber's temperature decreases (similar effect as a Rich Mixture) and the drop of the temperature brings as a consequence that the Carbon Monoxide (CO) emissions and the Hydrocarbons that are not burnt (HC), increasing heavily its contribution to the pollution to the Environment.

If the sparkplug is hotter than necessary:

The Combustion Chamber's temperature increases (similar effect as a Lean Mixture) and this increase of temperature, brings as a consequence that the emissions of Nitrogen Oxide (NOx) also increase dangerously, increasing heavily its contribution to the pollution to the Environment.

Those are some of the main strongest reasons why:

According to the studies of the Environmental Protection Agency (EPA), the National Safety Council (NSC), and the Environmental Health Center, which is an organization from the National Safety Council of the United States:

“vehicles are responsible for two thirds of the emissions of carbon monoxide, and half of the Ozone emissions at ground level”.

“the driving and functioning of vehicles, among others, is the main source of release of pollution in the world”.

“Vehicles with engines release millions of tons of pollution in the air, each year”.

These emissions of vehicles, qualified as toxins, are the origin of at least 1,500 cases of cancer in the USA, per year, heart, asthmatic and respiratory diseases, ophthalmic and different type of allergies; as well as contributing in serious Environmental Problems, such as acid rain as well as Smog.

Also of the climate changes that all of us are seen, like the greenhouse effect, the thaws in the Andes mountains, and the increasingly more frequent and disastrous hurricanes.

The mobile source are responsible of the major pollutants that are killing the earth, what overcomes largerly the pollutants generated by the most agressive chimneys of the heavy industries. The contribution of the vehicles to the Air pollutants are:

2,617,229 tons of CO
713,808 tons of HC
520,103 tons of Nox

You dont´have to take our words. See what the most respected American and foreign authorities and experts have to say about it:

"70 % of the cars checked had spark plugs in sufficiently poor condition to cause one or more engine problems”. (38.5% by spark plugs hotter than neccesary. 37% by spark plugs colder than neccesary).
U.S. Department of Transportation – DOT.

“ARB recognizes the operational benefits associated with the use in motor vehicles of spark plug with correct heat ranges. Estimation of spark plug heat range could be a usefull tool to the automotive technician to ensure the use of spark plugs meeting optimum specifications. We commend you of the interest in the proper maintenance of vehicles....... we suggest offering the Spark Plug Heat Range Determinator as a measurement device to professional mechanics and Do it Yourself users”.
Air Resources Board from the California Environmental Protection Agency of the United States of America in a letter to Spark Plug Heat Range Determinator´s offices.

“They have developed a valuable contribution to preserve the world environment..... regarding the dangerous impact, in balance with the environment, of vehicles with gas engines.... their proposal is simple, practical and economic, giving a valuable solution to the difficult problem to be solved and of great incidence to the world environment; also eliminating from the skies important volumes of air contaminants”.
Letter of the National Environment Council of the Peruvian Govern, nominating the Spark Plug Heat Range DETERMINATOR team, to the VOLVO Environment Prize, in the year 2002.