Hydrocarbons and the Air

Hydrocarbons and the Air





Emissions of Automobiles in America: A Controlled Investigation

Learning Team Z

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Team Member Name Here

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Psych 315

October 8, 2059

Mr. Avery

Emissions of Automobiles in America: A Controlled Investigation

A growing body of research by leading industry experts shows an alarming rate of hydrocarbons in the atmosphere throughout the lower 48 contiguous United States and Canada. Harmful emissions from automobile tailpipes and engine compartments contribute to the rising rate of hydrocarbons released into the atmosphere each year. Preston (2005) indicates an average atmospheric increase of 3.8% in hydrocarbons each year since 1999. He estimates that a 50% reduction in automobile emissions will lower the overall level of harmful hydrocarbons in the air by 23%. Engineers from the Oppenheimer Group, a leading manufacturer of emissions control products, produced an emissions control device that can be retrofitted to any automobile exhaust system through the tailpipe, and modified to fit in the engine compartment of most cars and trucks. The Oppenheimer Group installed its emissions control device in the exhaust system of 36 randomly selected cars from across the country. Industry standards reveal that automobiles not equipped with the Oppenheimer Group’s emissions control device emit an average of 100 pounds of pollutants per year into the atmosphere with a standard deviation of 15. The Oppenheimer Group predicts that cars equipped with their emissions control device will differ from cars not equipped with their emissions control device in the number of pounds of pollutants released into the air. H1:


≠ 100 and H0:


= 100. 



Forty drivers and their respective cars were recruited to participate in the emissions control test from various cities across the country via a radio, newspaper, and billboard advertisement campaign which lasted 60 days prior to the beginning of the investigation. Four participants withdrew before the study began due to prior commitments that would interfere with their ability to complete all 30 days of the study. Drivers ranged in age from 18 to 59 years with a mean age of 34.12. Nineteen participants were female (52.78%); seventeen were male (47.22%). Twenty-nine participants were married (74.36%). The remaining seven were single or divorced (19.44%). The average education level for all participants was 11.63 years. Average income reported for all participants was $39,700 per year. For all 36 participants, the average number of miles driven per month was 1,140.18. Eight of the participants were unemployed at the beginning of the study (22.22%). All others had one or more jobs. A 25 dollar inducement was offered to those participants who completed the investigation.


The Oppenheimer Group’s emissions control device was retrofitted into the tailpipe of all 36 automobiles by Oppenheimer’s technicians who flew to each participant’s city to install the device. The device was place at both ends of the catalytic converter; that is, the exhaust fumes traveling from the engine first passed through the emissions control device before passing through the catalytic converter and then through a second emissions control device prior to being released through the tailpipe into the air.


All participants were given Truman’s (1999) questionnaire of driving habits that included questions about driving infractions and/or tickets over the past five years. Those drivers who indicated 3 or more traffic tickets within the past year, and/or 1 or more DUI and DWI infractions within the past 5 years were excluded from the study in the interest of maintaining a high degree of integrity within the investigation.


Drivers were instructed to maintain their normal driving routine throughout the 30 day trial. Exhaust emissions were measured on 20 of the 30 days (Monday – Friday) during the study by inserting an emissions meter into the tailpipe and also by taking emission readings from each automobile’s engine compartment. Emissions per car were totaled and the totals for each automobile were added together at the end of the study. Yearly totals were estimated from the monthly totals at the end of the 30 day trial.


A “Z” test was the statistical procedure chosen to determine the significance or non-significance of the hydrocarbons released into the air by the emissions control device. The Oppenheimer Group tested their emissions control device using a two-tailed test @ .05 alpha. The average amount of hydrocarbons released into the air by all cars not equipped with the emissions control device was 100.00 pounds per year with a standard deviation of 15.00.

All thirty-six automobiles in the test group released an average of 99.00 pounds of hydrocarbons into the air per year. The standard error of the mean was 2.50. That is, the population standard deviation of 15.00 divided by the square root of N where N = 36 yielded the standard error of the mean of 2.50. The resulting “Z” test yielded an obtained value of –0.40 against a two-tailed critical value of –1.96. The obtained value, indicated below, was not significant. The mean pounds per year for the sample (M = 99.00, SD = 4.31) dropped slightly from the pounds per year for the population (M = 100.00, SD 4.54).

Z = -0.40, p > .05.


The present study attempted to demonstrate that the Oppenheimer Group’s emissions control device released less pollutants into the air from cars on which the device was installed vs the pollutants released into the air from automobiles on which the emissions control device was not installed. After the 30 day trial, no significant difference was found between those automobiles on which the emissions control device was installed compared to those automobiles on which the device was not installed.

Hydrocarbon pollutants were an inherent part of this study and will continue to be released into the air at no less than Preston’s estimated 3.8% per year until effective measures can be put in place to reduce the level of harmful emissions released from automobile exhaust systems.

This study was limited in that only 36 participants and their automobiles volunteered to participate. A broader scope of participants from a wider geographical area would be desired. Also, global implications can scarcely be discussed since the present trials were conducted entirely within the United States where the level of atmospheric hydrocarbons is at minimum 3 times greater than other industrialized nations (Jennings, 2004). Similar research in regions outside the U.S. may have achieved different results.

Future research should include more participants with a broader range of automobiles to include small, medium, and large privately owned trucks. Further, trials should be conducted in all of the various climatic regions in the country and at multiple elevations. Moreover, the researchers feel that a longer study would produce more accurate data instead of estimating yearly emission totals from one 30 day study. Lastly, each emissions control device was installed new on each of the 36 automobile in the study. Even if results had been significant, the research team would want to know if the emissions control device would continue to reduce the level of harmful pollutants into the air and for how long until it needed to be replaced. Perhaps further research can answer these important questions.


Jennings, W.R (2004). Filling our air with poisons: A case study of pollutants in

our air. Hydrocarbon Quarterly, 34, 165-184.

Preston, H.G. (2005). Hydrocarbons and the Air: The Poisoning of America.

New York: McGraw Hill.

Truman, J.C. (1997). Driving Habits: Integrity of the American Driver. Journal of

Automobile Engineering and Science, 15, 125-133.



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