Particulate Pollution Tied to Dementia

From a University of Washington News Release, the Air Pollution and Dementia Study and Commentary cited below:

Using data from two large, long-running study projects in the Puget Sound region of Washington State— one that began in the late 1970s measuring air pollution and another on risk factors for dementia that began in 1994 — University of Washington researchers identified a link between air pollution and dementia.

In the University of Washington study, Rachel Shaffer, the lead author and whose PhD dissertation this was, found that a small increase in the levels of fine particle pollution (PM2.5 or particulate matter 2.5 micrometers or smaller) averaged over a decade at specific addresses in the Seattle area was associated with a greater risk of dementia for people living at those addresses.

“We found that an increase of 1 microgram per cubic meter of exposure corresponded to a 16% greater hazard of all-cause dementia. There was a similar association for Alzheimer’s-type dementia,” said now Dr. Shaffer, who conducted the research as a doctoral student in the UW Department of Environmental & Occupational Health Sciences.

Rachel Shaffer et al. used the Adult Changes in Thought (ACT) cohort study based in Seattle to examine associations between exposures to fine particulate matter with a diameter ≤2.5μm (PM2.5) and incident all-cause dementia. Once a patient with dementia was identified, the researchers compared the average pollution exposure of each participant leading up to the age at which the dementia patient was diagnosed. Exposure data was based on the home address of the individuals and not activity levels or locations. The researchers also had to account for the different years in which these individuals were enrolled in the study, since air pollution has dropped significantly since the 1970’s when the ACT study began.

In their final analysis, the researchers found that just a 1 microgram per cubic meter difference between residences was associated with 16% higher incidence of dementia. One microgram per cubic meter difference in PM2.5 pollution is extremely small and subtle.

“We know dementia develops over a long period of time. It takes years —even decades — for these pathologies to develop in the brain and so we needed to look at exposures that covered that extended period,” Shaffer said. And, because of long-running efforts by many UW faculty and others to build detailed databases of air pollution in our region, “we had the ability to estimate exposures for 40 years in this region. That is unprecedented in this research area and a unique aspect of our study.”

Although not the first to report on this subject, and this study proved only correlation not causation, Bete Ritz and Yu Yu in their invited commentary state: “this study makes an important contribution to the field, “not only due to its size and careful exposure and outcomes assessment, but especially because it suggests that the cognitive health of even a low-risk, low-exposure population may be affected. “

As the researchers state: “Air pollution exposure is ubiquitous globally. Strong evidence links air pollutants to cardiovascular events and diabetes, both known to affect cognition in elders. However, data in support of the contributions of air pollution to aging-related cognitive decline are only just emerging (Paul et al. 2019). As exposures are chronic and affect large populations, even modest risks result in large numbers of cases (Kuenzli 2002).” So, as the particulate pollution from western wildfires moves east, mask up.



Rachel M. Shaffer, Magali N. Blanco, Ge Li, Sara D. Adar, Marco Carone, Adam A. Szpiro, Joel D. Kaufman, Timothy V. Larson, Eric B. Larson, Paul K. Crane, and Lianne Sheppard; Fine Particulate Matter and Dementia Incidence in the AdultPublished:4 August 2021CID: 087001https://doi.org/10.1289/EHP9018

Hurricane Frequency Is Not Increasing

I was glued to the weather channel this past weekend to watch Hurricane Henri  head for New England, but was relieved when Henri was downgraded to a tropical storm. I have read and heard the climate change is responsible for increasing hurricane intensity and frequency.  Satellite data from the last 40-45 years is the source of that belief. Over the weekend I had plenty of time to read up on the latest research. What I found is that according to an article published recently in Nature Communications that may not be true.

In the article, “Changes in Atlantic major hurricanefrequency since the late-19th century,” that I have cited below, Dr. Gabriel Vecchi a climate scientist from Princeton University, found that the frequency  of hurricanes has not increased in the Atlantic over the past 168 years. The trend in intensity was not examined, though the data brings into question if the intensity of storms has increased over the 168 year period.

The scientists found: “that recorded century-scale increases in Atlantic hurricane and major hurricane frequency, and associated decrease in USA hurricanes strike fraction, are consistent with changes in observing practices and not likely a true climate trend.” The scientists developed a method using probabilities and known storm tracks to adjust the old observation data and found no change in hurricane intensity and frequency over 1851-2019. Instead, they found a decrease in hurricane frequency about 50 years ago and a recovery.

Even though the North Atlantic (NA) basin is a minor contributor to global cyclone storm frequency, Atlantic hurricanes have a well documented long-term records of their track and frequency mostly because of the damage the storms bring when they make landfall as Categories 3–5.  

In homogenizing the historical data from 1851–2019 the scientists discovered that the increases in basin-wide hurricane and major hurricane activity since the 1970s was not a trend caused by climate change, but a recovery from a deep minimum in the 1960s–1980s. This same recovery may have impacted the conclusions from other studies done on storm intensity in the 1979-2019 period.

The scientists postulated that air pollution containing particulates blocked and scattered sunlight and induced reductions in major hurricane frequency. They go on to say that this could have masked a century-scale greenhouse-gas warming contributions to North Atlantic major hurricane frequency. Meanwhile, it is not in their data.

The accepted climate models and theoretical arguments indicate that in a warming world the hurricane peak intensity and intensification rate should increase, along with frequency. So, climate models currently increase the overall number of Categories (3, 4, or 5) hurricanes in response to CO2 increases.

The scientists do not believe that their work provides evidence against the hypothesis that greenhouse-gas-induced warming may lead to an intensification of North Atlantic hurricanes. Kossin et al. in their work using satellite data for the period of 1979-2017 found a statistically significant upward trend in the intensity of hurricanes and tropical cyclones globally. The new study may bring that finding into question, but it is argued that substantial variability may obscure trends computed over the past century, and pollutant-driven reduction in hurricane activity over the 1960s–1980s may have obscured any greenhouse induced hurricane intensification over the 20th century.

Other research has supported the idea that the number of hurricanes has not increased, but there is a strong belief amongst climate scientists that storm intensity is increasing, though there is no documentation of that as yet. Data selection period and the difficulty of collecting accurate data in the past has limited the ability to see if the trends exist clearly.

Dr. Vecchi and his research team are the go-to researchers on climate impacts on hurricanes and extreme weather events. This is one of those instances when time and further data collection will ultimately hold more answers or at least information. In the meantime, remember that storms can be deadly, rising sea level increases storm surge and flooding; and we should always take storm warning seriously.

Vecchi, G.A., Landsea, C., Zhang, W. et al. Changes in Atlantic major hurricane frequency since the late-19th century. Nat Commun 12, 4054 (2021). https://doi.org/10.10 38/s41467-021-24268-5

 

Colorado River

The Federal Bureau of Reclamation released the Colorado River Basin flow and water level projections for Lake Powell and Lake Mead for 2022. After 22 years of drought within the basin, the level of Lake Mead was forecast to fall below 1,066 feet above sea level. Anything below 1,075 feet above sea level triggers the stage one water shortage restrictions. The annual flow of the Colorado River is estimated to have fallen about 20% in the 21st Century compared to the 20th Century due to both rising temperatures and drought.

from Bureau of Reclamation

There has been a drought in the Colorado River Basin for the past 22 years. This combined with higher temperatures has lead to what some are calling aridification of the region. Lake Mead has seen more than 130-foot drop in the water level since the turn of the century. Water releases down river from Lake Meade and Lake Powell reservoirs are determined by the Bureau of Reclamation forecast reservoir water elevations. Plans that were developed over the past two decades lay out detailed operational rules for these critical Colorado River reservoirs. Based on projections in the study:

• Lake Powell’s January 1, 2022, water elevation will be 3,535 feet - about 165 feet below full. Based on this projection, Lake Powell will release 7.48 million acre-feet in water year 2022.
• Lake Meade will operate in its Level 1 Shortage Condition for the first time ever. The required water reductions negotiated under the series of negotiated interim guidelines for Lower Basin Shortages and Coordinated Operations of Lake Powell and Lake Mead:

1. Arizona must reduce water use by 512,000 acre-feet, which is approximately 18% of the state’s annual apportionment.
2. Nevada must reduce water use by 21,000 acre-feet, which is 7% of the state’s annual apportionment.
3. Mexico will receive 80,000 acre-feet less, which is approximately 5% of the country’s annual allotment.
4. California as the most senior water right holder in the lower basin does not have a reduction under Level 1 shortage conditions.

These cuts in water usage are nowhere near enough to stop the falling water levels in the reservoirs. In July drought operations were implemented to protect Lake Powell under the Upper Basin Drought Response Operations Agreement which will release up to an additional 181,000-acre feet of water from upstream  units of the Colorado River Storage Project to Lake Powell to ensure that the water level remains high enough to generate hydropower. Hydropower generation in the basin’s reservoirs can supply more than 4,200 megawatts of electrical power to the Western States, reducing the use of fossil fuels

More than twenty years of drought, drying out of the West due to changing climate, and growing populations throughout the basin are creating a water crisis. Under the  terms of the Colorado Compact the Upper Basin States must deliver 7,500,000-acre feet of water each year for the Lower Basin States and 1,500,000-acre feet for Mexico, an allotment for the tribes and an allotment to nature. The Lower Basin states of Arizona, California and Nevada were first to address their growing problem by creating a Drought Contingency Plan to address California’s use of the original excess of the Lower Basin allotment.

The Upper Basin States of Colorado, New Mexico, Utah and Wyoming still have to agree to their own Drought Contingency Plan to prevent a “Compact Call” under the Colorado Compact which would simply cut water to users across the Upper Basin States proportionally if they are unable to deliver the water, they are required to send through Lake Powell under the Colorado Compact.

Today, the river provides water to 40 million people and 5.5 million acres of farmland in Colorado, Wyoming, Utah, New Mexico, Nevada, Arizona and California, 29 Native American tribes and the Mexican states of Sonora and Baja California. Even without climate change, paleoclimate records show a history of tremendous droughts in the region, and now more than 40 million people (in the upper and lower basins) depend upon the Colorado River’s waters for their water supply.

1922 Colorado River Compact, negotiated by the seven basin states (Colorado, Nevada, Utah, New Mexico, Wyoming, Arizona, California, ) divided the Colorado River basin into upper and lower portions, allotted the Colorado’s water on the basis of territory rather than prior appropriation. Before this agreement was negotiated allocation of water rights (ownership) was based on historic use, first to use the water owned it in perpetuity. In a land where water was wealth and all water was diverted from its natural location, this was how it was done. The allocation of water rights based on territory allowed development to proceed in the lower basin (essentially California) while safeguarding supplies for the upper basin. Then, as now, California's growth and demand for water was viewed with concern by her neighbors.

The problem now is that the allocations promised under the Colorado Compact was based on an expectation that the river's average flow was 16.4 million acre feet per year  and ignored the needs of nature and the tribes. Subsequent studies: however, have concluded that the long-term average water flow of the Colorado is less. In addition, according to the University of Arizona, records going back to paleolithic times (more than 10,000 years ago) indicates periods of mega-droughts in the distant past. 

Now with more than twenty dry years, the reservoirs have dwindled to their lowest levels recorded. 

Allotted shares of water in the basin to both the United States and Mexico exceeds the average long-term (1906 through 2018) historical natural flow of under 16.0 million acre-feet. To date, the imbalance has been managed, and demands largely met by slowly using up the considerable amount of reservoir storage capacity in the Colorado River system that  once held approximately 60 million acre-feet (nearly 4 years of average natural flow of the river). It was assumed that drought years would be followed by wet year to refill the reservoirs. The basin is in its 22nd year of drought.

Child Dies in North Carolina

 From a NCDHHS new release:

The North Carolina Department of Health and Human Services reports that a child died Friday after developing an illness caused by an amoeba that is naturally present in freshwater. The child became ill after swimming in a private pond at their home in central North Carolina in early August. 

Laboratory testing at the federal Centers for Disease Control and Prevention confirmed the child’s illness was caused by Naegleria fowleri, an amoeba (one-celled living organism) commonly found in freshwater. Naegleria fowleri, does not cause illness if swallowed but can be fatal if forced up the nose, as can occur during jumping into water, diving, water-skiing or other water activities.

Symptoms of Naegleria fowleri infection — an infection of the brain called primary amebic meningoencephalitis (PAM) — start with severe headache, fever, nausea and vomiting and progress to stiff neck, seizures and coma and can lead to death. These rare infections usually occur when it is hot for prolonged periods of time, which results in higher water temperatures and lower water levels. Naegleria fowleri grows best at higher temperatures up to 115°F.

"Our heart-felt condolences and sympathies are with the family and friends of this child," said State Epidemiologist Zack Moore, M.D. "Although these infections are very rare, this is an important reminder that this amoeba is present in North Carolina and that there are actions people can take to reduce their risk of infection when swimming in the summer."

There is no means to eliminate this amoeba from fresh bodies of water, in warmer areas where this infection has been more common, recommended precautions include:

• Limit the amount of water going up your nose. Hold your nose shut, use nose clips or keep your head above water when taking part in warm freshwater-related activities. 
• Avoid water-related activities in warm freshwater during periods of high water temperature and low water levels. 
• Avoid digging in or stirring up the sediment while taking part in water-related activities in shallow, warm freshwater areas.

Naegleria fowleri infections are rare, with only 147 known infections in the U.S. from 1962 through 2019. North Carolina had six cases during that time period. This amoeba can cause severe illness up to nine days after exposure. A person cannot be infected with Naegleria fowleri by drinking water, the amoeba is not found in salt water, or in properly maintained and chlorinated pools.

With the climate warming and heat waves increasing we in Virginia should be aware of this risk to protect our children.

 

Prince William Service Authority

Recently, I attended the Service Authority’s Annual Water Academy on Zoom. It was an easy way to learn about drinking water and waste water resources in Prince William County. The following is from that program and a presentation given by Don Pannell, Deputy General Manager at Prince William County Service Authority, to the Board of County Supervisors.

Utilizing current projections of water usage, the County and the Metro-Washington Council of Governments estimates that the current level of water capacity is sufficient until at least 2040. This does not take into consideration any future development of the rural crescent which has not been factored into the current projection. Depending on the level of development in the rural crescent, this date will likely occur much sooner. In addition, these projections, also, do not take into account any increase in drought due to climate change.

The Prince William Service Authority distributes about 11 billion gallons of water per year to the residents of the county that are on public water. The communities that receive their water from the Service Authority can be seen below in the blue, pink and yellow areas. The remainder of the county obtains its water from private wells.

The maximum amount of water that can be delivered by the Service Authority is 67.8 million gallons a day (MGD). The source of that water is:

• Fairfax Water: 62.4 MGD
• Lake Manassas: 5.0 MGD
• Service Authority wells: 0.4 MGD

The Occoquan Reservoir is an essential portion of the Fairfax Water supply. We are dependent on Fairfax Water for 92% of the Prince William public water supply, yet 66% of the Occoquan Watershed is in Prince William County has been unprotected from development and pollution. Fairfax preserved 21,000 acres in Fountainhead park to protect the Occoquan River and Reservoir. “On November 17, 2020, the Board issued Directive No. 20-86 for staff to develop a protection overlay district for the Occoquan Reservoir.” 

In fiscal year 2021 the average daily water demand was 30.0 MGD with the maximum day at 49.3 MGD. As you can see 92% of the water capacity for the county comes from Fairfax Water which in turn draws water from both the Potomac River and the Occoquan Reservoir. At present, less than 1% of the public water supply comes from public groundwater wells. There was a time (40 years ago) when most of the water in Prince William came from public supply wells, but that came to an end when the public wells in Manassas were discovered to be contaminated with solvents. The only groundwater study of Princes William County was done to identify the extent of the solvent contamination in 1997.

Based on growth projected that were made using the previous comprehensive plan that did not allow any public water use in the Rural Crescent or consider any change increase in duration and severity of droughts due to climate change, exiting capacity should be sufficient until 2040. However, the climate is changing and Prince William County is developing within the Rural Crescent.

Prince William Service Authority also provides waste water treatment for the public sewer customers in the county. Wastewater treatment is provided by the Fairfax run Upper Occoquan Service Authority and the H.L. Mooney AWRF plant in Woodbridge. The Service Authority treats 10.6 billion gallons of wastewater each year. Prince William has a newer separate sewer system, so we do not have combined sewer storm events. Total sewer treatment capacity: 43.8 MGD H.L. Mooney AWRF: 24.0 MGD Upper Occoquan Service Authority : 19.8 MGD. Both wastewater treatment plants are expected to expand their capacity in the future Upper Occoquan Service Authority by 2030 and Mooney by 2040.

IPCC Climate Report

On Monday after a yearlong delay due to covid, the U.N.  Intergovernmental Panel on Climate Change(IPCC) released the first report on Climate Change since 2013. The report, issued by the IPCC’s Working Group I and approved by 195 member governments, is the first in a series leading up to the 2022 IPCC Sixth Assessment Report and serves as a motivational leadoff to the 26th UN Climate Change Conference of the Parties (COP26) in Glasgow on October 31, 2021-November 12, 2021.

Since the IPCC report is based on previously published peer reviewed work there were no surprises. (I will admit that I only read the Summary for Policymakers and sections of the discussion on the climate models in key findings.) Climate change is widespread and intensifying. The concentration of greenhouse gases in the atmosphere is at its highest level since the dawn of mankind. Before the COVID-19 pandemic when the data set used stops, emissions of carbon dioxide had been rising by about 1% per year on average for the past decade. Renewable energy use has been expanding rapidly, but much of the renewable energy is being deployed alongside existing fossil energy, not replacing it.  All the climate models tie the rise in temperature to concentrations of atmospheric carbon dioxide. The planet has warmed 1.1 degrees C since the late 19th century and is expected to warm an additional 0.4 degrees C in the next 20 years.

“At 1.5°C global warming, heavy precipitation and associated flooding are projected to intensify and be more frequent in most regions in Africa and Asia (high confidence), North America (medium to high confidence) and Europe (medium confidence). Also, more frequent and/or severe agricultural and ecological droughts are projected in a few regions in all continents except Asia.”

From IPCC

Mankind in their burning of fossil fuels and covering the earth with concrete is responsible for this rise in temperature. No actions that nations can likely agree to take at November’s COP26 meeting can change this trajectory we only have some hope of moderating it.  That is the key finding of the latest scientific report from the IPCC. Scientists use the five projection scenarios to demonstrate the difference that our coordinated action can make, but also warn: “The magnitude of feedbacks between climate change and the carbon cycle becomes larger but also more uncertain in high CO2 emissions scenarios (very high confidence). However, climate model projections show that the uncertainties in atmospheric CO2 concentrations by 2100 are dominated by the differences between emissions scenarios (high confidence). Additional ecosystem responses to warming not yet fully included in climate models, such as CO2 and CH4 fluxes from wetlands, permafrost thaw and wildfires, would further increase concentrations of these gases in the atmosphere (high confidence).”

The IPCC report finds that changes in the Earth’s climate in every region and across the whole climate system have occurred and are resulting in increase in extreme weather events. “In 2019, atmospheric CO2 concentrations were higher than at any time in at least 2 million years (high confidence), and concentrations of CH4 and N2O were higher than at any time in at least 800,000 years (very high confidence).” “Global surface temperature has increased faster since 1970 than in any other 50-year period over at least the last 2000 years (high confidence).”

Recent work had shown an oversensitivity of the climate models to changes in CO2 levels; however, the actual warming of the earth has gone on long enough to identify the inconsistency and the to constrain their projections somewhat. Nonetheless, the report finds the forecast warmer climate will intensify weather events and the resulting flooding or droughts; but the location and frequency of these events depend on projected changes in regional atmospheric circulation, including monsoons and mid-latitude storm tracks and cannot be projected at this time.

It is virtually certain that global mean sea level will continue to rise over the 21st century. Long term “sea level is committed to rise for centuries to millennia due to continuing deep ocean warming and ice sheet melt, and will remain elevated for thousands of years (high confidence).”

“Limiting human-induced global warming to a specific level requires limiting cumulative CO2 emissions, reaching at least net zero CO2 emissions, along with strong reductions in other greenhouse gas emissions. Strong, rapid and sustained reductions in CH4 emissions would also limit the warming effect resulting from declining aerosol pollution and would improve air quality.” There are the marching orders for COP26 in Glasgow this fall. Good luck to us all.

Ethanol in Fuel

I have never been a fan of adding ethanol to fuel, but that may be changing. MIT researchers have found a way to achieve high yields of ethanol with different types of cellulosic feedstocks. Most ethanol in the U.S. is made from corn, not cellulose waste and though corn ethanol is technically a “renewable” energy source it has a large environmental footprint. Currently, around 40 % of the U.S. corn harvest goes into ethanol. Corn that could be used to feed people is instead used to make ethanol. This uses cropland, pesticides, fertilizer, and water to produce the corn just for that.

The Renewable Fuel Standard (RFS) is a federal program that requires fuel sold in the United States to contain a minimum volume of renewable fuels. The RFS required renewable fuel to be blended into transportation fuel in increasing amounts each year, escalating to 36 billion gallons by 2022. The RFS program only looks at  greenhouse gases (GHGs) relative to the petroleum fuel it replaces, the program does not look at the overall environmental costs of the “renewable” fuel. It was calculated that the RFS increased the need for cropland by 23% because ethanol production is limited in large part by its reliance on corn to produce ethanol.

from LuoyeChen et al 2021 Environ. Res.

According to Tyler Cowen, professor of Economics at George Mason University, in his book, An Economist Gets Lunch, New Rules for Everyday Foodies, “(To put ethanol into gasoline) costs a lot more money than does traditional gasoline, once the cost of the subsidy is included. Sadly, it does not even make the environment a cleaner place. The energy expended in growing and processing the corn is an environmental cost too…the nitrogen-based fertilizers used for the corn are major polluters. Ethanol subsidies are a lose-lose policy on almost every front, except for corn farmers and some politicians.” “For millions of (people in poor countries) it is literally a matter of life and death and yet we proceed with ethanol for no good reason…(Biofuels) has thrown millions of people around the world back into food poverty.”

According to a recently published article “The economic andenvironmental costs and benefits of the renewable fuel standard” LuoyeChen et al 2021 Environ. Res. Lett. 16 034021, maintaining the corn ethanol mandate at 15 billion gallons until 2030 will lead to a discounted cumulative value of an economic cost of $199 billion over the 2016–2030 period. Their cost estimate includes $109 billion of economic costs and $85 billion of net monetized environmental damages, however; they do not account for the cost of water resources. The additional implementation of the cellulosic biofuel mandate for 16 billion gallons by 2030 increases the economic cost by $69 billion which they find will be partly offset by the net discounted monetized value of environmental benefits of $20 billion, resulting in a net additional cost of $49 billion over the 2016–2030 period.

Currently, feedstocks such as straw and woody plants which are wastes are difficult to use for biofuel production because they first need to be broken down to fermentable sugars, a process that releases numerous byproducts that are toxic to yeast, the microbes most commonly used to produce biofuels. Yet, there are more than a billion tons of cellulosic biomas including switchgrass, wheat straw, and corn stover (what is left in the fields after the corn is harvested). According to a U.S. Department of Energy study this is enough biomass to replace 30%-50% of the petroleum used for transportation if the cellulosic biomass could be cleanly and efficiently turned into ethanol.

Now, MIT researchers have found a way to achieve high yields of ethanol with different types of cellulosic feedstocks, including switchgrass, wheat straw, and corn stover. From MIT News: “The MIT team built on a technique they had developed several years ago to improve yeast cells’ tolerance to a wide range of alcohols. In their new study, the researchers engineered yeast so that they could convert the cellulosic byproduct aldehydes into alcohols, allowing them to take advantage of the alcohol tolerance strategy they had already developed. They tested several naturally occurring enzymes that perform this reaction, from several species of yeast, and identified one that worked the best. Then, the scientists used directed evolution to further improve it.”

Yeast are generally not very efficient at producing ethanol from toxic cellulosic feedstocks; however, when the researchers used their improved enzyme and spiked the reactor with the membrane-strengthening additives, the strain more than tripled its cellulosic ethanol production, to levels matching traditional corn ethanol. “What we really want to do is open cellulose feedstocks to almost any product and take advantage of the sheer abundance that cellulose offers,” says Felix Lam, an MIT research associate and the lead author of the new study.

Gregory Stephanopoulos, the Willard Henry Dow Professor in Chemical Engineering, and Gerald Fink, the Sokol Professor at the Whitehead Institute of Biomedical Research and the American Cancer Society Professor of Genetics in MIT’s Department of Biology, are the senior authors of the paper, which appeared open access in Science Advances.

Though the President has gone all in on electric vehicles looking to transition to half the vehicles sold in the United States to be electric vehicles by 2030, that goal would require more electricity, a re-imagined and modernized grid, charging stations and still there would remain a tremendous number of gas-powered vehicles. The average age of a car in the United States is almost 12 years.  So, even in the world where half of all cars sold in the United States are electric, there would still be fuel burning vehicles for decades to come. Ethanol is a renewable, domestically produced transportation fuel. Whether used in low-level blends, such as E10 (10% ethanol, 90% gasoline), E15 (10.5% to 15% ethanol), or E85 (flex fuel cars) a gasoline-ethanol blend containing 51% to 83% ethanol, depending on geography and season ethanol blends can reduce emissions and be part of the fuel lineup for the future.