We’ve Come a Long Way in Reducing Particulate (Soot) Air Pollution
The term “smog” – derived from a combination of “smoke” and “fog” – first appeared in the early 20th century to describe conditions in London.
London, long famous for its “pea-soup” Thames River valley fog, found conditions deteriorated even further during days-long smog events, made worse by the proliferation of coal-burning fireplaces and gigantic coal-fired power plants producing electricity to run the metropolitan area.
The problem became even worse in the postwar period due to the increased use of low-quality, highly sulfureous coal.
Smog reached a new dangerous peak in the first week of December 1952 as an air inversion formed over the city, trapping as much as 1,000 tons of smoke particles, 2,000 tons of carbon dioxide, and 370 tons of sulfur dioxide (which combined to form 800 tons of sulfuric acid).
According to the UK Met Office, this “Great Smog of London” caused widespread breathing problems, and estimates indicate that 4,000 people (and possibly as many as 12,000) died prematurely due to complications from air pollution events during the London winter of 1952 – 1953.
The worldwide publicity generated by the Great Smog of London set the stage for new regulations to tackle the problem of air pollution that affected cities, particularly those that commonly experience air inversions that trap pollution close to the ground, including Los Angeles, Delhi, Beijing, Mexico City, and Tehran.
New clean air regulations were enacted in the London region in 1954, 1956, and 1968. Environmental activists
Los Angeles had its own significant “smog event” in the summer of 1943 that reduced visibility to just a couple of city blocks. In reaction, the Los Angeles County Air Pollution Control District was formed in 1947; the first air pollution agency in the USA.
Despite efforts to regulate nearby power plants, oil refineries, and chemical plant pollution, visible air pollution continued to persist throughout the LA basin to the frustration of environmental activists and healthcare providers.
In the early 1950s, Dr. Arie Haagen-Smit, a biochemistry professor on sabbatical leave from Caltech, made the connection between automobile exhaust and the persistent air quality problems in the region. Haagen-Smit discovered that the large amounts of unburned hydrocarbons and nitrogen oxides (NOx) emitted by LA’s growing number of automobiles underwent a powerful photochemical reaction when exposed to strong sunlight – generating the air pollution we know as smog.
The first federal Clean Air Act was passed into law in 1963. In 1966, California instituted the first tailpipe emission standards. The California Air Resources Board (CARB) was enacted in 1967, and it has led the nation in regulating automobile tailpipe emissions, such as unburned hydrocarbons and NOx. In 1970, President Nixon, a Southern California native, created the Environmental Protection Agency (EPA) by executive order, later ratified by the House and Senate.
Next Major Change on the Horizon: Cleaner Port and Shipping Operations
Regulations introduced by the federal Clean Air Act and the stricter California Air Resources Board (CARB) have reduced vehicle pollution significantly since the 1970s, thanks to the introduction of new technologies, such as selective catalytic converters for gasoline engines that reduce NOx pollution and convert carbon monoxide (CO) into carbon dioxide and unburned hydrocarbons into carbon dioxide and water.
Diesel engines, which can emit significant amounts of particulates (soot) into the air, remained relatively unregulated until 1997, when the EPA enacted new emission standards for the 2004 model year and later diesel engines. The regulations were tightened again for 2010 model year engines, limiting emission to 0.2g/bhp-hr (grams per brake horsepower-hour) for NOx and 0.01 g/bhp-hr for particulate matter (PM).
What’s Next on the Horizon for Controlling Air Pollution?
Air pollution regulators are looking at reducing the amount of pollution emitted by maritime ports and ship traffic.
Traditionally, most ocean-going ship traffic has relied on so-called “bunker fuel” (known formally as heavy fuel oil or HFO) to power onboard diesel engines for propulsion and on-board electricity production.
Unfortunately, bunker fuel is widely criticized for being among the “dirtiest of the dirty” fuel sources. It’s typically made from the residuals of petroleum refining operations, and burning it is associated with especially high amounts of sulfur emissions and particulate materials (PMs).
The widespread use of bunker fuel is also a major reason why the world’s ports are pollution hotspots – due to a combination of ships burning bunker fuel as they sit at the docks and a large number of diesel trucks often idling nearby, waiting to load or offload containers.
There are three ways to improve the situation.
The first is to accelerate the shift away from bunker fuel to cleaner diesel fuel. The EPA has already extended the so-called Tier 4 regulations for maritime diesel engines in US-flagged vessels, but this regulation does not apply to the majority of cargo ships that are flagged overseas. To address this, the EPA has also joined other nations in efforts to beef up the existing international maritime pollution regulations, known as MARPOL Annex VI NOx emission control program, at the 81st Marine Environment Protection Committee (MEPC) held in London in May 2024.
Last amended in 2020, the MARPOL regulations have helped reduce sulfur emission by 70%, but the EPA and other national environmental regulators want to move to a Net Zero reduction.
Many shipbuilders, including cruise ships, are now operating on cleaner diesel fuels and some have gone further, implementing power propulsion fueled by cleaner liquified natural gas.
The second way to improve port pollution is to implement so-called Alternative Marine Power (AMP) systems. These allow ships tied up to the docks to turn their onboard diesel power generators off in favor of using shore power systems provided by the port.
The third way to reduce the concentration of air pollution at ports is to implement electric power trucks to handle the time-consuming container loading and unloading operations onto semi-truck trailers, which can then be transferred to conventional trucks.
The Inflation Reduction Act of 2022 is providing the EPA with $3 billion in funding for the Clean Ports Program to address these issues at the nation’s ports.
How Does Particulate (Soot) Pollution Affect the Climate?
For every action, there is a reaction.
And so, this may be the case in reducing the amount of hazardous particulate material (soot) pollution.
On the positive side, reducing particulates and aerosols in the air has made lives better for millions of people, thanks to reduced concentrations of smog, leading to easier breathing and improved health outcomes, including reducing the number of premature deaths each year.
But could there be unintended consequences from reducing the particulate pollution in the atmosphere?
The answer is yes according to a new paper published in Nature Communications and Environment, in which a research team at the Goddard Space Flight Center in Maryland has expressed concern that the rapid reduction (circa 80%) of sulfur dioxide pollution emitted from international maritime shipping has created an inadvertent geoengineering “shock” to the environment that could inadvertently raise global temperatures significantly.
How Much Warmer Could the Climate Become if We Eliminate All Sulfur and Particulate Pollution?
How much could the sudden reduction in sulfur and particulate pollution raise global temperatures?
The researchers at Goddard Space Flight Center postulate that this change could lead to a doubling of the planet’s warming rate throughout the current decade (e.g. the 2020s) compared to a 1980 baseline.
They also contend that the currently observed warm weather throughout 2023 is consistent with their claim.
How is this happening?
The researchers believe that the warming effect of the increasing amount of greenhouse gases emitted since the Industrial Revolution has been offset (e.g. mitigated) by the cooling effect of aerosol emissions, such as sulfur pollution.
In other words, the greenhouse gases congregating at high levels in the atmosphere that cause the planet to heat up have been held in check by other pollutants, such as sulfur emissions from sources such as international shipping.
To estimate the effect of reducing sulfur pollution, sea surface temperature (SST) data was collected using the GEOS Atmospheric Data Assimilation System (ADAS), which uses terrestrial and satellite sources. This was input into computer simulation experiments using the Goddard Chemistry Aerosol Radiation and Transport (GOCART) aerosol module within NASA’s Goddard Earth Observing System (GEOS) Earth System Model (ESM).
After running the atmospheric computer simulations that take the recent dramatic reduction in sulfur pollution into account, the researchers conclude that unusually high temperatures seen in 2023 will become a new baseline (e.g. new normal) for temperatures in the future.
Upcoming Reports on Estimating Sea Level Rise and How GeoEngineering Could Make a Difference
If these computer simulations are correct, the study by the Goddard Space Flight Center researchers points to a much warmer planet sooner than many of us were expecting.
A rapidly warming planet may have profound implications for sea level rise and permanent changes in the Atlantic Meridional Overturning Circulation (AMOC). We’ll be looking at these issues in our October 2, 2024 executive report.
We’ll also investigate the legal policy hurdles regulating geoengineering efforts to tame climate change in our November 27, 2024 report as well.
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