Air Pollution: Historical Perspective and Control Technologies

Comprehensive practice flashcards covering the history of air pollution, industrial chemical processes (Leblanc and Solvay), major historical smog and pollution disasters, and emission control legislation.

According to Paracelsus (1493–1541), what determines whether a substance acts as a poison?

The dose determines whether a substance is harmful, summarized by the dictum: "It is the dose that makes it harmful or not."

How did the USEPA (2007) define air pollution?

The presence of contaminants or pollutant substances in the air that interfere with or harm human health or welfare, or produce other harmful environmental effects.

What are the six criteria air pollutants identified by the EPA?

Particulate Matter ($PM_{2.5}$ and $PM_{10}$), Ozone ($O_3$), Nitrogen Dioxide ($NO_2$), Sulphur Dioxide ($SO_2$), Carbon Monoxide ($CO$), and Lead ($Pb$).

What are the volumetric percentages and concentrations of Nitrogen ($N_2$) and Oxygen ($O_2$) in dry, clean air at sea level?

Nitrogen ($N_2$) comprises $78.08\%$ ($780,800\,\text{ppm}$) and Oxygen ($O_2$) comprises $20.95\%$ ($209,500\,\text{ppm}$).

What are the volumetric percentages of Argon ($Ar$) and Carbon Dioxide ($CO_2$) in dry clean air at sea level?

Argon ($Ar$) accounts for $0.93\%$ ($9,300\,\text{ppm}$) and Carbon Dioxide ($CO_2$) accounts for $0.038\%$ ($385\,\text{ppm}$).

Why did Queen Eleanor move from Nottingham to Tutbury Castle in 1257?

She moved to escape the heavy smoke caused by the burning of coal.

How does the prevailing wind across the UK influence regional air pollution levels in England?

The prevailing wind arrives from the West across the Atlantic Ocean, creating cleaner air and lesser pollution in the West of England compared to the East.

What regulation did King Edward I implement in London in 1273 regarding fuel consumption, and what was the penalty?

He banned the burning of sea coal in London, with violations punishable by execution.

What abatement technology was recognized and constructed to alleviate air pollution in 16th-century England?

Chimneys built with tall stacks, which were considered an expensive investment at the time.

What proposal did John Evelyn present to King Charles II in 1661 to address London's air pollution?

He urged the relocation of pollution-emitting industries to remote areas outside the city, though his proposal was ignored by the government.

Why were air pollution abatement measures generally neglected by authorities during the 17th century?

The government primarily comprised factory owners who had no incentive to relocate, and lower overall life expectancy made infectious diseases, poor diet, and insanitary living conditions far greater priorities.

Which historic soda ash manufacturing process is represented by this reaction scheme?

The Leblanc process.

What dangerous by-products were produced by the Leblanc process during soda ash manufacturing?

Gaseous hydrogen chloride ($HCl_{(g)}$), an acidic vapour causing lung and eye irritation, and solid calcium sulphide ($CaS_{(s)}$), which decomposed into toxic, flammable hydrogen sulphide gas ($H_2S_{(g)}$) upon exposure to rain or moist air.

What is the primary solid chemical by-product of the Solvay process, and what are its common uses?

Calcium chloride ($CaCl_2$), which is used for curing cement, de-icing roads, and as a desiccant.

What was the emission reduction target and outcome mandated by the UK Alkali Work Act 1863?

It required a $95\%$ reduction in hydrochloric acid ($HCl$) emissions during a 5-year trial period, reducing emissions from $14,000$ to $45\,\text{tpa}$.

What engineering technique was introduced under the Best Practical Means (BPM) amendments to the Alkali Act?

The use of charcoal-packed towers washed with water to absorb and dissolve gaseous $HCl$, creating liquid $HCl$ for bleaching powder manufacture and reclaiming sulphur from $CaS$ waste.

What geographical and meteorological factors contributed to the severity of the 1952 Great Smog of London?

The broad, flat Thames River Valley trapped stationary air beneath an anticyclone originating from the northwest, causing a severe temperature inversion and near-freezing temperatures.

What is the atmospheric difference between normal air temperature gradient and a temperature inversion?

Under normal conditions, air temperature decreases with height; during a temperature inversion, air temperature increases with height, trapping colder air and concentrated pollutants near the ground.

What chemical reactions caused widespread fatalities during the December 1952 London Smog?

Fog droplets condensed around airborne soot particles while $SO_2$ gas oxidized to form dilute sulphuric acid ($H_2SO_4$) with a pH of $1.6$, triggering lethal mucus build-up in the lungs and fatal heart attacks.

On which days did pollutant concentrations and deaths reach their peak during the 1952 London Smog?

Sulphur dioxide ($3830\,\mu\text{g/m}^3$) and smoke particulates ($4460\,\mu\text{g/m}^3$) peaked on 8th December, and daily deaths peaked at $919$ on 9th December.

What three core measures were established by the UK Clean Air Act of 1956?

It banned the burning of coal in designated urban areas, relocated power stations away from cities, and granted subsidies for households to convert to cleaner heating fuels.

What occurred during the 1930 Meuse Valley disaster in Belgium?

A dense fog and temperature inversion over a 15-mile valley trapped emissions from 27 factories, causing $6,000$ illnesses, cattle deaths, and $60$ human fatalities linked to sulphuric acid aerosol and suspected fluorine emissions.

What conditions and industrial emissions precipitated the 1948 Donora air pollution episode in Pennsylvania?

A temperature inversion from October 27–31 trapped emissions from a zinc works, steel plant, wire mill, and nail galvanizing plants in the narrow Monongahela River valley, sickening $6,013$ people and killing $20$.

What chemical was accidentally released during the 1984 Bhopal plant disaster in India, and what were the consequences?

A storage tank rupture released $40\,\text{tonnes}$ of methyl-isocyanate (MIC), causing $3,300$ immediate deaths and exposing over $200,000$ people to chronic respiratory and ocular diseases.

How severe was the air pollution resulting from the 1997 Indonesian forest fires?

El Niño-driven droughts produced dense regional haze causing over $30,000$ respiratory cases across Southeast Asia, with visibility falling below $30\,\text{m}$ and air quality equating to smoking $100\,\text{cigarettes per day}$.

Why did sulphur dioxide ($SO_2$) emissions decrease relative to GDP per capita around 1980 while methane ($CH_4$) increased?

$SO_2$ decreased due to acid rain regulations and flue gas desulphurisation technologies, whereas $CH_4$ increased because higher incomes drove expansion in cattle farming and waste landfills.

What notable trend occurred in China's air quality and emissions data around 2011 and 2013?

In 2011, $CO_2$ emissions decoupled from GDP growth under the 12th five-year plan, and the 2013 Action Plan for the Prevention and Control of Air Pollutants triggered an overall reduction in almost all major air pollutants.