I am an air quality meteorologist and a pragmatic environmentalist. My blog usually addresses topics where I appeared opposed to mainstream environmentalist dogma so it has been asked why I even consider myself an environmentalist. I support evidence based environmental controls. Since I started work in my field in 1976 there has been tremendous air quality improvement that addressed serious health and welfare problems. I want to document some of the improvements I have been a party to as an environmentalist in the electric generating industry on Earth Day 2018.
The two primary pollutants associated with acid rain are sulfur dioxide and nitrogen oxides. They are also associated with small particulate matter. United States sulfur dioxide emissions in 1970 31.2 million tons but were only 2.7 million tons in 2016 (91% reduction). United States nitrogen oxide emissions in 1970 26.9 million tons and in 2014 12.4 million tons (54% reduction).
I have been working in New York State most of my career. According to the EPA Clean Air Markets Division, over the twenty year period 1997 to 2016, the sulfur dioxide emission rate dropped 98% from 0.83 to 0.017 lbs per mmBtu. In the same time period, nitrogen oxides emissions dropped 75% from 0.24 to 0.061 lbs per mmBtu.
I am proud of the pollution control improvements at the facilities I worked with before I retired. In particular, I supported the Huntley and Dunkirk coal-fired power plants in Western New York from 1981 to 2010. My job was to report the emissions. The earliest sulfur dioxide and nitrogen oxides data I have for those two plants is from 1984 when the sulfur dioxide emission rate was 2.04 lbs of SO2 per mmBtu and the nitrogen oxide emission rate was 0.56 lbs of NOx per mmBtu. When I retired in 2010, the sulfur dioxide emission rate was 0.527 lbs of SO2 per mmBtu (81% reduction) and the nitrogen oxide emission rate was 0.159 lbs of NOx per mmBtu (73% reduction).
We worked with the New York State Department of Environmental Conservation to implement the control equipment necessary to reduce the emissions. Sulfur dioxide emissions were reduced by changing the sulfur content of the fuel, ultimately using Powder River Basin coal from Wyoming that had a much lower sulfur content that what was used in 1984. It is a testament to the operating staff at those plants that they figured out how to use a much different coal than what the plants were designed to burn when the plants were built before 1960. Nitrogen oxides were controlled by changing the burners a couple of times to more advanced technology and ultimately by adding selective non-catalytic reduction control systems. The addition of a baghouse with activated carbon injection also markedly reduced particulate, opacity and Hg emissions. Sadly despite all these improvements the cost of coal relative to natural gas made both plants uneconomic and they have since shut down.
As a result of these emission reductions, there has been a similar reduction in air pollution concentrations. EPA provides pollutant concentration trend data that documents those reductions. At EPA’s 42 nation-wide SO2 trend monitoring sites the annual average concentration has gone from 154 micrograms of SO2 per cubic meter in 1980 to only 20.2 in 2016 (87% reduction). At EPA’s 23 nitrogen dioxide trend monitoring sites the annual average concentration has gone from 111 micrograms of SO2 per cubic meter in 1980 to only 43.7 in 2016 (61% reduction).
Unfortunately, there has not been a similarly large relative concentration decrease for ozone. At EPA’s 206 nation-wide ozone trend monitoring sites the annual fourth maximum of daily maximum 8-hour average has gone from 0.101 ppm in 1980 to 0.070 in 2016 (31% reduction). Ozone is much more complicated pollutant because it is not directly emitted. Instead it is created in a photo-chemical reaction between nitrogen oxides and volatile organic compounds. As a result there are many more categories of sources to control which complicates improvements.
EPA and others tout the importance on human health of reductions in particulate matter, especially with small particulate matter known as PM-2.5 (the size of the particles is 2.5 microns). EPA only provides trends of PM-2.5 since 2000 because the monitoring equipment was not deployed until then. At EPA’s 455 nation-wide PM-2.5 trend monitoring sites the annual average concentration has gone from 13.4 micrograms per cubic meter in 2000 to only 7.7 in 2016. However, there is a strong correlation between ambient concentrations of PM-2.5 with SO2 and NO2. I did a multiple regression with the 2000-2016 PM-2.5 observations with SO2 and NO2 to guess at the ambient level in 1980. I predict that PM-2.5 concentrations have dropped 68% between 1980 and 2016.
The progress the United States has made in air quality improvement gets overlooked too often today when we seem to hear mostly about problems like ozone that still need to be addressed. However, before 1970 New York City was very polluted and that, for the most part, has been cleaned up. One should also keep in mind that there were some spectacularly wrong predictions made around the first earth day in 1970. Those predictions include the following air quality predictions:
- In January 1970, Life reported, “Scientists have solid experimental and theoretical evidence to support…the following predictions: In a decade, urban dwellers will have to wear gas masks to survive air pollution…by 1985 air pollution will have reduced the amount of sunlight reaching earth by one half….”
- Paul Ehrlich predicted in 1970 that “air pollution…is certainly going to take hundreds of thousands of lives in the next few years alone.” Ehrlich sketched a scenario in which 200,000 Americans would die in 1973 during “smog disasters” in New York and Los Angeles.
Given the demonstrated improvement in air quality as opposed to apocalyptic projections of the past I hope readers keep that in mind when you hear current environmental doom and gloom stories.