week 1: ambient air pollution & health effects

ozone (O3)

• layer in the stratosphere, thinnest in the tropics (around the equator) and denser towards the poles

• at the ground level, ozone is a health hazard

• major component of photochemical smog

• common in suburban regions downwind from cities

stratospheric level ozone

• forms a protective layer that serves a vital function: it absorbs the wavelength of solar radiation aka UV-B (ultraviolet-b)

• sunburn, skin cancer, eye damage, cataracts aka eyes (estimated 10% reduction ozone layer → 25% increase non-melanoma skin cancer

• suppress immune system

• DNA mutation

ozone depletion contributors

• chloro-fluoro-carbons (CFC)

  • used as refrigerants (notably in air conditioners), as agents in some manufacturing processes, and formally as propellants in spray cans; takes 10-20 years to get to the stratosphere and 65-385 years to break down

• halogen compounds

  • fire fighters used bromine-containing halogens to put out fires

in the stratosphere, intense UV radiation breaks the CFC molecules apart, which lead to…

releasing the chlorine acts as a catalyst (takes part in several chemical catalyst) yet at the end emerges unchanged and is able to react again

1 chlorine atom average destroys

1,000 ozone molecules before converted into form harmless to ozone

1987 montral protocol on substances

first global agreement to restrict CFCs and deplete ozone layer

acid rain

• reactions in the atmosphere and can fall many miles from where the pollution originated

• Oxides of sulphur and nitrogran produce acid aerosol - H2SO4, HNO3

Health Effects of Acid Rain

• Impaired forest growth → reduced ecosystem productivity

• Increase in acidity for lakes and rivers

• Death of fish and wildlife

• Weathering of monuments and buildings

• Health impacts for those prone to respiratory ailments

Trans-boundary issue

pollutants reaching higher altitudes may be transported thousands of km, so areas with little to no local industry can still experience high levels of toxic contamination

smog

• industrial smog (burning sulfur-rich oil or coal)

• photochemical smog (sunlight reaction to pollutants aka brown air smog; tropospheric ozone)

atmospheric pressure low to high

london killer smog of 1952

• Average smoke and burning culter rich oil or coals and the relationship to death for 12 London sites

• Peak in the number of deaths coincided with the peak in both smoke and pollution levels

1970

earth day

Clean Air Legislation

• Air Pollution Control Act (1955): first federal air pollution law, identifying air pollution as a national problem

• Clean Air Act (1963): first national air pollution control that set emissions standards for stationary sources

• Clean Air Act (1970): added identification of critical pollutants and established ambient air quality standards; A full list of 188 hazardous air pollutants targeted

• Revision (1990): provision for acid rain, urban smog, toxic air pollutants, ozone protection, marketing pollution rights, fugitive emissiosof voltile organixs, ambient ozone, soot, and dust, and NOx emmisions

clean ari act 1970 revised

CRITERIA POLLUTANTS

• Primary standards:

  • Protect public health

• Secondary standards:

  • Protect public welfare

AIR TOXICS

• No primary or secondary standards that limit pollutant concentrations in the air

• Maximum achievable control technology: reduce emissions from specific industrial "source categories" (like chemical plants, oil refineries, or steel mills)

6 critical common air pollutants

• Particulate matter

• Carbon monoxide

• Nitrogen oxided

• Ground level ozone (smog)

• Lead

• Sulfur dioxide

nonattainment

failure to meet the standards

by law, EPA must review the 6 critical pollutants every…

5 years

gaseous, aerosol, or particulate pollutants other than the 6 critical pollutants except for lead…

are present in air in low concentrations, but are toxic and persistent

health effects of ozone

• chest pain

• coughing

• throat irritation

• congestion

• worsen bronchitis

• asthma

• emphysema

• reduce lung function and inflame the linings of the lungs

• permanent scarring

• lung cancer

Nitrogen Dioxide (NO2)

• gaseous products of combustion from both stationary sources and from motor vehicles

• in contrast to ozone, nitric oxide is found at higher levels indoors than outdoors

Health Effects of Nitric Oxide

• increased respiratory tract symptoms, reduced lung function from direct inflammation increased respiratory tract infection from effects of defence mechanisms.

• deteriostion of health status of persons with chronic respiratory diseases

Sulfur dioxide and acid aerosols (SO2)

• emitted by fossil fuel combustion (coal and oil fired power plants and industrical processes

  • Before the 1970 Clean Air Act, sulfur dioxide was primarily released from smoke stacks at relatively low heights within the ground-based mixing layer, so it reacted quickly to deposited on the ground on vegetation and surfaces

  • Limits placed on sulfur dioxide concentrations, power plants and other emission sources had tall stacks installed to reduce local ambient air concentrations

Particulate Matter

• classified by their size (mass median aerodynamic diameter

  • PM10: <10 μm

  • PM2.5: <2.5 μm

  • Ultrafine PM (UFP): <0.1 μm (mass infinitesimal for UFP, but number enormous)

Health Effects of Particulate Matter

heightened ambient levels of PM2.5 lead to respiratory illnesses and cardiovascular endpoints, and ultrafine can penetrate cell walls and the blood-brain barrier which leades to organs absorbing it

Carbon Monoxide (CO)

reacts with blood hemoglobin

Health Effects of Carbon Monoxide

• tissue hypoxia, organs with high metabolic rates like CNS and the cardiovascular system

• high levels lead to death

• low levels lead to cardiovascular & neurobehavioral (headaches/nausea/fatigue)

• Vulnerable population like fetus, infants, people with anemia or chronic heart or lung disease, high altitude residents, smokers

Current and Future Conditions

• In the U.S. air quality has improved in the last deceased, exepct for areas that still sever traffic and wildfires

• Air quality is poor in developing countries

Air pollution in 2023

2nd risk factor for mortality worldwide

How does air pollution worsen COVID-19 outcomes

• Decreases immunes system function to fight viruses

• Causes inflammation and oxidative stress in lunges

• Can lead to severe pneumonia

• Cardiovascular and metaboli csystem can worsen

What are the two major air pollution problems at global level?

• 1) Ozone Depletion: CFCs and Halogen compounds destroying the ozone layer (stratospheric ozone). UV radiation breaks apart CFC molecules and release chlorine atoms which in turn reacts with ozone and destroys it

• 2) Climate change: carbon dioxide and methane emission levels are harder to treat than just having a substitute for ozone layer

What are the two major air pollution problems at regional level?

• 1) Acid Rain: pollutants (oxides of sulfur and nitrogen) produce acid aerosols that can travel long distances

• 2) Photochemical smog: "smoke" + "fog" industrial smog and photochemical smog (triggered by UV rxn with pollutants)

What are the major air pollution problems at local level?

• 1) Nitrogen Dioxide (NO2): high levels indoors than outdoors, gas products of combustion from stationary sources and motor vehicles

• 2) Sulfur dioxide and acid aerosols: SO2 emitted by fossil fuel combustion (coal, oil)

• 3) Particulate matter (PM): fine particles getting inhaled and penetrated

• 4) Volatile Organic Compounds (VOCs): volatile and readily inhalable (ex: butane, propane, octane) emitted naturally by decomposition and industrial activities, precursors of smog

• 5) Carbon Monoxide (CO): reacts with blood hemoglobin

ozone

good up (statosphere), bad nearby (troposhpere)

voc

volatile organic compounds from vegetation and industrial sources + nitrogen oxide from automobiles + power plants + sunlight = ground level ozone

why does particulate matter PM size matter

• High ambient levels of PM 2.5 lead to mortality, respiratory illness, and cardiovasuclar endpoints

• UFP can penetrate cell walls and the blood-brain barrier and can be easily absorbed into vital organs

• The bigger the number (10) = larger particle

• The smaller the number (2.5)

• The size of the particle determines how far  and what it penetrates into the body

in which atmospheric region does the ozone layer occur and what would be the human health consequences of ozone layer destruction?

• The ozone layer occurs in the stratosphere and can be destroyed by man-made chemicals

• Human health consequences: sunburn, skin cancer, eye damage, cataracts, suppresses immune system, DNA mutation

on an overcast or cloudy day, would you expect any O3 buildup due to smog? Explain why.

no, would not expect any O3 buildup due to smog. Photochemical smog relies on UV radiation in order to be created.

what international treaty went into effect in 1987, aiming at mustering worldwide effects to protect the ozone layer? What is the major action called by this treaty?

• 1987 Montreal Protocol on Substances that deprete ozone

• First global agreement to restrict chloro-fluoro carbon (CFC)s and try to find alternative to CFC products

7. Which geographical area in the U.S. has the most significant acid rain problem and what are the environmental and human health effects of acid rain?

1) The Northeastern United States has the most significant acid rain problem.
This is because of the large number of cities, the dense population, and the concentration of power and industrial plants in the Northeast.

2)
- Impaired forest growth reduced ecosystem productivity
- Increase in acidity for lakes and rivers
- Death of fish and wildlife
- Weathering of monuments and buildings
- Health impacts for those prone to respiratory ailments.

What are the differences between industrial smog and photochemical smog?

1) Industrial smog:
-Burning sulfurrich oil or coal creates SO2, SO 3, sulfuric acid, ammonium sulfate.
-Carbon leads to CO2 and CO.
-Days with stagnant air, usually winter.

2) Photochemical smog:
-Smog from reaction of sunlight with pollutants
-The kind that blankets so many American cities today
-"Brown air smog"
-Contains tropospheric ozone, NO2, VOCs, 100 more...
-Hot sunny days in urban areas create perfect conditions.

Why is O3 presence in the troposphere a paradox to O3 in the stratosphere?

Good up, bad nearby

In the stratosphere (good): Ozone forms the "Ozone Layer". Its chemical role here is to absorb the sun's ultraviolet (UV) light. Without this "good" ozone, life on the surface would be sterilized by radiation

In the Troposphere (bad): Near the ground, ozone is a toxic gas. because it is highly reactive, it oxidizes (chemically burns) lung tissue when inhaled and damages the cells of plants, reducing crop yields.11 Here, it is the primary ingredient of smog.

what does VOC stand for? What is the role of VOC in smog formation?

• Volatile organic compounds from vegetation and industrial sources + nitrogen oxide from automobiles + power plants + sunlight = ground level ozone

• VOCs are volatile and readily inhalable ( butane, propane, and octane)

• VOCs are precursors of photochemical smog and react with nitrogen oxides emitted from vehicles, power plants and industrial activities to form ozone, which in turn helps the formation of fine particulates.

cite two ways in which hazardous air pollutants (HAPs) differ from criteria pollutants.

• The criteria pollutants have primary and secondary standards.
  

• The HAPs have no primary or secondary standards that limit pollutant concentrations in the air, but have maximum achievable control technology standards (MACT)

Particulate matter (PM) air pollution is sometimes categorized as PM10, PM2.5, or ultrafine particles. Why is particle size an important factor determining the adverse human health effects?

The size of the particles is related to their potential to cause health problems. Small particles, less than 10 micrometers, are the biggest problem because they can penetrate deep into the lungs, and some can even enter the bloodstream. Additionally, UFP can also penetrate cell walls and the blood brain barrier and can be absorbed into vital organs.