By: Calvin B. Parnell, Jr. PhD and P.E.

Congress and EPA are Preparing a Major Tax on GHG Emissions.

Congress just passed the “Clean Energy”, “Green Jobs”, “Climate Change”, “Global Warming”, “Cap and Trade”, or “Green House Gas Bill” depending upon who is talking. What is in this bill and why do those who support it want it passed by the Senate this fall? It is confusing when one reads the news papers and watches the news. I am going to do my best to explain in simple English why so many in the media and elected officials have chosen the path of having the U.S. do the following:

1.      Redefine CO₂ as an air pollutant to be regulated under the Clean Air Act (CAA). It is not an air pollutant (as defined by the CAA) and has never been regulated under the authority of the CAA although many environmentalists have labeled green house gasses (GHG) as air pollutants for years. (Why now?)

2.      Congress is asked to approve the Waxman-Markey bill consisting of more than 1000 pages that mandates industries to significantly reduce GHG emissions by 2020 and 2050. (Why?)

The answer to these two questions is relatively simple:

Politicians and media subscribe to the theory that global warming is caused by increasing concentrations of CO₂ in the atmosphere and we in the U.S. must lead the way by reducing GHG emissions.

·         The media has helped to convince the public that this theory for global warming (climate change) is irrefutable. (It is not!)

There are computer models that predict catastrophic events in the future (2050) if the CO₂ concentrations continue to rise.

·         The climate change alarmists want the U.S. to take a leadership role in reducing our emissions of GHG, no matter the cost and irrespective of whether it will lower the concentrations of CO₂ in the atmosphere that they believe is causing global warming.

One possibility of why we have so many names for the Waxman-Markey bill is that politicians want to generate as much support as possible from the voting public. Who can be against a “Green Jobs”, “Clean Energy”, preventing “Climate Change” or reducing emissions of GHG? Using the different descriptions of this bill can result in confusing the public so that no one really knows the justification. There is a reason for creating the confusion. The media propaganda has been relatively successful in convincing the public and many politicians (both republicans and democrats) that we are experiencing global warming. The global warming theory is as follows:

Increasing concentrations of CO₂ (carbon) in the atmosphere as a consequence of burning fossil fuels causes the global warming.

Is global warming caused by increasing concentrations of CO₂?

EPA researchers Alan Carlin and John Davidson recently received publicity because they produced a report that was not forwarded to the high level group deciding the “Endangerment Findings” within EPA.  (It was shelved by his supervisor and they were told not tell anyone what was in their report.) Their report suggested that EPA should consider reevaluating the science supporting the global warming theory. These actions fuel a perception that there are those in EPA who do not want anyone to question the science of global warming. Is it possible that this theory is incorrect?

On April 17, 2009, the EPA Administrator responded to the court mandate. The “Endangerment Findings” were that GHGs “in the atmosphere do threaten the public health and welfare of current and future generations” and GHG emissions from new motor vehicles pose a threat of climate change.

A request for public comment was issued allowing 60 days for the public to respond. A number of requests to extend the public comment period on “Endangerment Findings” were rejected by EPA. Why? Is it possible that EPA did not want additional public input on this finding? It is a very significant finding and there is some question whether this finding is justified. The administrator’s finding is supportive of the Waxman-Markey bill. There is a perception that the bill’s supporters want to generate revenue by taxing emitters of GHG and are using the emotional support of the global warming which is supposed to be caused by increased concentrations of CO₂ in the atmosphere as the justification.  

The magnitude of mandated reductions of GHG emissions is enormous. According to EPA’s emissions inventories (April 15, 2009), we emit a total of less than 0.15 billion tons of “real air pollutants” (SO₂, NO_x, NMVOC, CO). The Waxman-Markey bill is mandating that we reduce our emissions of GHG from a projected 8 billion tons in 2020 to 6 billion tons. The reduction of 2,000,000,000 tons of GHG is 13 times more than the total emissions of real air pollutants! Real air pollutants are regulated under the authority of the CAA to limit public exposure to concentrations that will not cause health effects “with an adequate margin of safety”. The range of CO₂ concentrations that are of concern relative to global warming will not cause health effects according to EPA’s technical support documents for “Endangerment Findings” which states the following:

“Current ambient concentrations of CO₂ and other GHGs remain well below published exposure thresholds for any direct adverse health effects, such as respiratory or toxic effects.”

What happens if manufacturing plants, power plants, and cars and trucks in the U.S. reduce our emissions of GHG by 2 billion tons as prescribed by the Waxman and Markey Bill (H.R. 2454)?

• Will China or India reduce their emissions of GHG? (Probably not!) It is being reported that the number of coal fired power plants being built and put in production in these two developing countries will exceed our mandated reduction of GHG by 2020. China and India have an expanding manufacturing industry and need the relatively inexpensive electricity from coal to compete with the U.S.  Their coal fired power plants will almost assuredly not have the pollution controls that US plants have as mandated by the Clean Air Act.
• What happens if we reduce our GHG emissions and China and India increase their emissions of GHG by the same (or more) than we reduce. Will the rate of increased concentrations of CO₂ in the atmosphere be reduced? (The answer is NO! If this is the case, the justification of the Waxman-Markey bill based upon global warming does not “hold water”.) When someone brings this to the attention of the public, the response of the bill’s supporters is “this is a jobs bill.” In reality, it is a TAX Bill!

The cost of reducing GHG emissions by 2,000,000,000 tons could be very expensive. Unlike current controls for criteria pollutants, there are no abatement strategies for reducing CO₂ leaving a smokestack. The most logical and effective method of reducing emissions of CO₂ are to shut down coal fired power plants and limit the vehicle miles driven. Shutting down coal fired power plants will make it difficult to meet the public demands for electricity in the future and will likely increase the costs. There are pundits who are stating that the projected cost per person or family are small but do they really know how to calculate these costs?

What if this whole global warming concern caused by increased concentrations of CO₂ is based upon “junk” science? Is it possible that some other cause could be responsible for the periodic increases in global temperature? What if the computer models predicting disasters in 2050 are WRONG? The following is likely if our elected senators pass this bill this summer or fall:

• If CO₂ concentrations do not control the warming of the globe and we pass the Waxman-Markey bill, we will be reducing GHG emissions with no impact on global warming. It is possible that our country will lose manufacturing industries seeking less expensive labor and energy in other countries.

·         Thousands of reputable scientists, me included, remain convinced that it is possible that the science in support of global warming is not sound.

•  
  • There are reports that the increase in temperatures estimated by the global warming researchers preceded the increase in CO₂ concentrations.  This suggests that the increase in CO₂ concentrations could have been the result of increasing temperatures rather than CO₂ concentrations being the cause of the increased temperatures.
  •  There are reports that temperatures higher than what we have been experiencing recently occurred in the past when the CO₂ concentrations were much lower. How could this be? If the global warming theory is correct, CO₂ concentrations cause the warming. If we had low concentrations of CO₂, there should have been low temperatures.

The concept of justifying this bill because a computer model predicts disasters in 2050 is problematic. Computer models are often wrong.

Computer models are woefully inadequate to properly model a system as complex as a planetary climate system. Global warming theory relies heavily on results of computer models designed to predict the Earth’s climate. The results of computer models to forecast near term weather patterns are often incorrect.  Consider that the justification of this bill is in part an assumption that modelers can predict 40 years of climactic variability.

It is likely that the elected officials voting for this bill will not be around in 2050. Who do we hold accountable if they are not around and especially if they put this burden on us and our grandchildren with no ultimate benefit? This bill robs future generations of freedom and binds them to a tax bill with no opportunity to provide input. We used to call this taxation without representation. At the very least, there should be an expiration date or a sunset provision on this legislation which would require evaluation for considering of renewal in the future.

The “cap and trade” feature of the Waxman-Markey bill authorizes EPA to limit GHG emissions. Permits would be issued to authorize a certain level of GHG emissions. Fees would be accessed per unit of GHG emissions with a corresponding cap or limit in place. There are opportunities for the emitting source to seek “off sets”. “Off sets” are displaced CO₂ emissions from fossil fuels that are a consequence of the source sponsoring renewable green energy projects. For example, a coal fired power plant can sponsor a wind farm in a developing country. The CO₂ that would have been generated from equivalent power generation using fossil fuels could be used by the U.S. power plant to meet its cap.

It seems that many of those who should be concerned are trying to soften the impact of the bill rather than doing their best to defeat it. We live in changing times and difficult decisions are being made at a very fast pace. I do not believe Waxman-Markey bill will benefit this country. Global warming or global cooling will occur irrespective of our actions to reduce GHG emissions. Climate changes are much more difficult to predict with computer models than some would have you believe. The hypothesis that global warming (or cooling) is consequence of mans’ activities remains a hypothesis.

More to come.

Previous blog: Global Warming and Green House Gases (GHG) - What is the problem?

Dr. Parnell is a Regents Professor in the Department of Biological and Agricultural Engineering and is the Cotton Chair. He has been conducting research on Air Pollution Engineering for over 40 years. He has been teaching undergraduate and graduate classes in air pollution engineering for more than 18 years.

The following are specific comments on GHG reporting for fugitive emissions from cattle feed yards surfaces:

• EPA specified in the proposed GHG emissions reporting rule that the mandatory reporting in 2010 should only include CH₄ and N₂O from manure management. CH₄ from enteric fermentation was not included in the mandatory reporting proposal. This action can be interpreted as EPA deciding that enteric fermentation will not be regulated.  The justification for excluding reporting emissions of CH₄ from enteric fermentation of beef cattle emissions is not clear and should be addressed.  The most likely control for this source is reducing the number of cattle on feed which may be politically unacceptable. According to the EPA emissions inventory estimates, 17% of the total agricultural emission of CH₄ is attributed to beef cattle enteric fermentation. This is in contrast to less than 0.5% of the total U.S emissions of CH₄ from manure management. If the goal is to significantly reduce GHG emissions to slow the global warming process,  there is very little benefit to  requiring all beef cattle feeding operations to report their emissions of CH₄ from manure management

·         Likewise, the magnitude of the N₂O emissions in units of CO₂e from manure management for beef cattle feed yards are very small relative to the total U.S. emissions of N₂O (2.2%) and relative to the total emissions from all agricultural sources (3%). (These emissions take into account the global warming potential of 310.) The determination of emission factors for N₂O for fugitive sources is very difficult. The protocol of measuring concentrations downwind, subtracting upwind (background) and calculating fluxes will not work for this species. Background N₂O concentrations are reported to be 319 ppm. Based upon our engineering calculations, the downwind concentrations of N₂O will be approximately 20 to 30ppb (0.02 to 0.03ppm). The measurement uncertainty associated with the resulting emission fluxes (factors) is too large.

Calculations: (Reference EPA. 2009. Emissions Inventories)

GHG emissions of CH₄ with a global warming potential of 21 using 2005 as the reference year:

1.      Total emissions (CO₂e) from all sources of CH₄ in the U.S. in 2005= 562 million metric tons (10⁶ tonnes);

2.      Total agricultural emissions (CO₂e) from all sources of CH₄ in 2005= 186*10⁶ tonnes;

3.      Total enteric fermentation emissions (CO₂e) from all sources of CH₄ from all beef cattle on feed yards in the U.S. in 2005=98*10⁶ tonnes

4.      Total beef cattle manure management CH₄ emissions (CO₂e) from all beef cattle on feed yards in the U.S. in 2005=2.4*10⁶ tonnes

GHG emissions of N₂O with a global warming potential of 310 using 2005 as the reference year:

1.      Total emissions (CO₂e) from all sources in the U.S. in 2005=316*10⁶ tonnes)

2.      Total agricultural emissions of N₂O (CO₂e) from all agricultural sources in 2005= 223 million metric tons (10⁶ tonnes)

3.      Total manure management beef cattle emissions (CO₂e) from all sources of N₂O from all beef cattle on feed yards in the U.S. in 2005=6.5*10⁶ tonnes

Table 1. Mass fractions of GHG emissions in units of CO₂e from beef cattle operations. (Reference EPA. 2009. Emissions Inventories)

·         EPA selected a mandatory reporting threshold of 25,000 metric tons (10³ tonnes) for all sources. This threshold was justified using an economic approach. The data used to calculate the costs included many assumptions and estimates that are questionable. With the EPA’s published emissions inventory (April 15, 2009), an alternative means for determining mandatory reporting thresholds is available and could provide a more logical means for determining which facilities should be required to report.

·         The regulation of GHG emissions is limited to emissions inventories (annual emissions). The goal is to find ways to reduce annual emissions of GHG to slow down the increase in CO₂e to prevent climate change or global warming. Forcing small emitters to report their emissions when reduction of their GHG emissions would have little impact on the increase in the concentration of CO₂e in the atmosphere is illogical.

·         Using 2005 as the base year, the total GHG emissions from all sources were 7,110*10⁶ tonnes. The total mass of CO₂e emitted by cattle feed yards of CH₄ and N₂O were (2.4+6.5)*10⁶ = 9 million tonnes. It is assumed that CO₂ emitted by cattle feed yards will not be regulated because it is CO₂ that has been sequestered in the feed. Hence, only emissions of CH₄ (562*10⁶ tonnes) and N₂O (316*10⁶ tonnes) from manure management must be reported. These emissions amount to only 0.43% and 2.1% of the total emissions of CH₄ and N₂O emitted, respectively.

·         The 25,000 tonnes mandatory emission threshold for reporting relative to the total mass of GHG emitted in 2005 is very low threshold. The reductions by 2020 mandated by the H.R.2454 are approximately 2 billion tons (2*10⁹ tonnes). 25,000 tonnes are less than 0.2% of the total reduction mandated by 2020. Why has EPA listed such a low threshold? The many “small emitters” of GHG will be spending much effort to comply with no net benefit to the goal of reducing the atmospheric concentration of CO₂e.

·         The number of cattle on feed yards that would result in required mandatory reporting was listed as 89,000 head. This number is incorrect. Using the data in table 1 and the reported 14 million (10⁶) head as the total number of head on feed yards in the U.S., the 25*10³ tonnes corresponds to 37,600 head not 89,000 head.

Calculations: (Reference Table 1)

Beef Cattle Manure Management Emissions (BCMM)

BCMM = [2.4 (CH₄) + 6.5 (N₂O)]*10⁶tonnes/year = 9*10⁶tonnes/year

Emission Factor (EF) = 9*10⁶tonnes/year/14*10⁶ head of cattle on feed

EF = 0.665 tonnes/hd-yr

Number of head on feed to emit 25*10⁶tonnes = 25,000/0.665= 38,000 head on feed.

Summary of Comments:

1.      GHG emissions should not be regulated as a “regulated” pollutant under the CAA. There are no direct health effects associated with breathing concentrations of CO₂e in the atmosphere. The costs in terms of Title V permitting and associated Title V fees would be overwhelming.

2.      The magnitude of manure management (CH₄ and N₂O) CO₂e emissions from cattle feed yards is very small relative to other sources. It is unlikely that any significant reductions of GHG will be obtained from regulating this source.

3.      The magnitude of enteric fermentation (CH₄) CO₂e emissions from cattle feed yards is significant and is not included in the mandatory reporting. Environment special interests will insist that this source be regulated. This should be addressed by EPA in the proposed rule. How will belching and passing gas be regulated? It seems that the only method to reduce this source of GHG will be to limit the number of cattle on feed yards. This may be unacceptable to the public.

4.      The method used to have all sources emitting 25*10³ tonnes required to report GHG emissions is flawed. It is recommended that some means of exempting small sources of GHG using EPA’s emissions inventories would be a better method. 25*10³ tonnes of CO₂e is less than 0.0000035% of the total GHG emitted in 2005.

5.      The mandatory reporting threshold for cattle on feed yards should be corrected. It is not 89,000 head.

-

Wake up everybody. The panic by Congress and EPA over Global Warming is going change the way we live and it is not justified!

By Dr. Calvin B. Parnell, Jr.

Introduction:

As a consequence of recent actions taken by the courts and EPA, a natural occurring gas in nature, carbon dioxide (CO₂), will be likely be a regulated pollutant under the authority of the Clean Air Act (CAA). This action was initiated by environmentalists, lawyers, politicians, and some misguided scientists. A Supreme Court decision in April, 2007 forced EPA to determine whether (or not) emissions of greenhouse gases (GHG) cause or contribute to air pollution or whether the science is too uncertain to make a reasoned decision. On April 17, 2009, the EPA Administrator responded to the court mandate. The “Endangerment Findings” were that GHGs “in the atmosphere do threaten the public health and welfare of current and future generations” and GHG emissions from new motor vehicles pose a threat of climate change. These findings and the associated technical support documents are open for public comment for 60 days following publication in the Federal Register. If the endangerment findings are not changed by the EPA administrator following a review of public comments by EPA, CO₂ will be regulated as an air pollutant under the CAA. If this occurs, it will be a mistake. The CAA was not designed to regulate non-pollutants.

In a related action, Congress is considering a law that will mandate reductions of GHG from sources in the U.S. by 2020 and beyond. (On May 21, 2009, the House Energy and Commerce Committee passed this law by a vote of 33 to 25. HR 2454 is now being considered by the House and Senate.) In contrast to EPA’s Endangerment Findings, the American Clean Energy and Security Act (ACESA) sponsored by Chairmen Waxman and Markey is a law. If passed, the reductions of GHG specified in ACESA are “mandated”. This law provides EPA with the enabling authority and mandate to limit emissions of GHG just as EPA regulates SO₂, NO_x, CO, and VOC emissions under the authority of the CAA.

Rules vs. Laws

The difference between proposed EPA rules and regulations and law are major. The differences are subtle and not fully understood by the public. There is no public comment period for ACESA as we have for EPA’s endangerment findings. The ACESA is a law just like the CAA. Changes are made by having Congress amend the law.

There were several GHGs including in EPA’s endangerment findings. CO₂, N₂O, and CH₄ are the three most prevalent GHGs. None of these are classified as air pollutants at this time. A concept of determining the equivalent mass of CO₂ per unit mass of the non-CO₂ GHG is being used for reporting and regulatory purposes. For example, one pound of natural gas (CH₄) emitted to the atmosphere is equivalent to 21 pounds of CO₂ and one pound of N₂O emitted to the atmosphere is equivalent to 310 pounds of CO₂. EPA published the annual emissions of all sources of GHG emissions in the U.S on April 15, 2009. All GHG emissions are listed in units of CO₂ equivalents (CO₂e).

On April 10, 2009, EPA proposed a rule to require U.S. sources to report all GHG emissions from their operations by a specified date in the future. It is anticipated that this action is a prelude for regulation and enforcement. (The comment period for this proposed rule ends June 9, 2009.)

The following is a summary of what is happening right now:

April, 2007 – The Supreme Court decision forced EPA to determine whether (or not) emissions of greenhouse gases (GHG) cause or contribute to air pollution.

April 15, 2009 - EPA published the inventories of annual emissions of CO₂e and conventional CAA air gaseous pollutants for all sources in the U.S.

April 17, 2009 - EPA has proposed that CO₂e be regulated as a pollutant under the CAA with the Administrator’s endangerment findings.

May 21, 2009 - The House Energy and Commerce Committee passed HR 2454 by a vote of 33 to 25. It is currently being considered by the House and Senate. Very specific limits on annual U.S. emissions of CO₂e are being placed on all sources by 2020 and 2050. The limiting of annual emissions of a pollutant or a proposed pollutant is in effect regulation of that pollutant!

Should CO₂e be treated as an air pollutant under the CAA?

The CAA was passed by Congress in 1970. It was the law that authorized the formation of the EPA. The conventional air pollutants regulated under the authority of the CAA were selected because of potential health and welfare effects. The definition of air pollution (Cooper and Alley, 2004) is as follows:

“Air pollution is the presence in the outdoor atmosphere of any one or more substances or pollutants in quantities which are or may be harmful or injurious to human health or welfare, animal or plant life or property, or unreasonably interfere with the enjoyment of life or property including outdoor recreation.”

The CO₂e concentration has risen from the pre-industrial concentration of 278ppm to 379ppm in 2005. The global concentration of CO₂e is the result of CO₂e emissions from sources in countries all over the world not just sources in the U.S. The U.S. cannot force other counties to reduce their GHG emissions. If we reduce our CO₂e emissions by one billion tons, will India and China do the same? (It is unlikely that developing countries will voluntarily reduce their emissions of GHG. Most of these developing countries do little to reduce emissions of conventional air pollutants. In contrast, the U.S. through the efforts of EPA and State Air Pollution Regulatory Agencies (SAPRA) have been successful regulating and enforcing limits of air pollution emission rates from all sources, protecting public health and welfare. Are GHG air pollutants?

The following is stated in the EPA technical support documents for Endangerment Findings:

“Current ambient concentrations of CO₂ and other GHGs remain well below published exposure thresholds for any direct adverse health effects, such as respiratory or toxic effects.”

 GHG (CO₂e) are not air pollutants! All living creatures inhale and exhale CO₂. We in the U.S. do not breathe the conventional CAA pollutants (SO₂, NO_x, CO, and NMVOC) except in concentrations regulated by EPA and SAPRA at levels that protect public health and welfare with “an adequate margin of safety”. The concentrations of CO₂e in the ambient air are not being labeled air pollutants to be regulated under the CAA because of health and welfare effects. The justification of this action is the belief that the world is facing a crisis. There are scientists, politicians and many citizens (global warming advocates) who believe the following climate change theory:

1. The Globe (world) is warming.
2. This warming is caused by increasing concentrations of CO₂e in the atmosphere. 
3. The causes of these increased concentrations of CO₂e are the burning of fossil fuels (coal, natural gas, and petroleum).
4. We in the U.S. must act now to reduce emissions of CO₂e or it will be too late. Major calamities in 2050 and beyond are being predicted by scientists using sophisticated models.

For those who believe in Global Warming caused by increased concentrations of CO₂e in the atmosphere, the only solution is a reduction the world’s emissions of CO₂e not just reducing CO₂e emissions from U.S. sources. These advocates believe that global warming caused by global concentrations of CO₂e is a fact not a theory and is irrefutable. Some refer to this group as alarmists. Statements have been made by those who support ACESA that we will achieve the reductions in CO₂e annual emissions in the Waxman/Markey bill with a new clean, green industry with many new jobs and a minimum of increased costs for the consumers of electricity and petroleum products.

The concerns of those who question the alarmist’s position are that the catastrophic projections are too dependent on inadequate computer models and that the U.S. will lose jobs, increase the costs of energy (electricity, methane, gasoline and diesel) and lose manufacturing capabilities to other countries. Irrespective of whether you accept Global warming as a fact that can not disputed or you question the science and model predictions, the following must be considered:

1. Human exposure to CO₂ concentrations in the range of 200 to 500ppm will have no impact on public health or welfare. GHG should not be regulated as an air pollutant!
2. If we in the U.S. reduce our emissions of CO₂e by the estimated 2 billion tons by 2020 to comply with the mandated reductions in the American Clean Energy and Security Act (ACESA) sponsored by Chairmen Waxman and Markey, will it change the global concentration of  CO₂e? The answer is NO!
3. There is nothing we in the U.S. can do to force developing countries such as China and India to stop building coal fired power plants that provide reliable, inexpensive electricity for their rapidly expanding manufacturing operations. There are reports that China will be adding 300 to 400 1000MW coal fired power plants in the near future. One 1000MW coal fired power plant emits 9 million tons of CO₂e per year. 300 will emit 2.7 billion tons per year. (This is more than our proposed reductions by 2020.) If other countries do not reduce their CO₂e emissions, will the world’s concentration of CO₂e stop increasing? The answer is NO!  
4. The new law (ACESA) is careful to set goals or benchmarks but unclear on how to achieve the mandated reductions. Reducing emission rates of CO₂e is not simple. We have developed mature and effective abatement systems for all of the conventional CAA pollutants (PM, SO₂, NO_x, CO, and VOC) but we have no proven abatement strategy for CO₂e other than shutting down power plants and reducing allowable vehicle miles driven.
5. According to EPA’s publication on emission inventories in April of this year, the magnitude of annual emissions of CO₂e from all sources in the U.S. relative to the total emissions of SO₂, NO_x, CO, and NMVOC in 2005 is 60:1. In other words, we emit more than 60 pounds of CO₂e for every pound of air pollutants causing heath effects. Is EPA equipped to take on this responsibility?
6. The bench marks set by ACESA are mandated and can not be changed other than by seeking amendments to ACESA in the future. What if we can not meet the mandatory reductions, is it possible that EPA will be forced to shut down plants? These are not targets such as miles-per-gallon for new vehicles that are routinely not met.
7. If Congress passes this law, we are stuck with it. It is possible that with the option of using “Cap and Trade with Offsets”, we will be having our U.S. coal fired power plants funding wind farms in developing countries to continue to produce inexpensive electricity from coal.

More to come.

Dr. Parnell is a Regents Professor in the Department of Biological and Agricultural Engineering and is the Cotton Chair. He has been conducting research on Air Pollution Engineering for over 40 years. He has been teaching undergraduate and graduate classes in air pollution engineering for more that 18 years.