This document discusses air pollution in Mexico City. It notes that Mexico City has historically had some of the worst air pollution in the world due to factors like industrial growth, population growth, and proliferation of vehicles. While pollution levels have dropped significantly since the early 1990s due to measures like emissions testing and reducing outdated vehicles, air pollution remains a major issue. The city's geography, being located in a high-altitude valley surrounded by mountains, traps air pollution and allows photochemical reactions to form more ozone and particles. Major pollutants include sulfur dioxide, nitrogen dioxide, carbon monoxide, and ozone. Actions to address pollution include "Hoy No Circula," a no-drive day program, and expanding bicycle infrastructure.

1. Air Pollution:
Concerns & Efforts
Case Studies: Distrito Federal, Mexico, D.F
Gabriella Perez
Fall 3015
SUST 410
Ramapo College of New Jersey

2. Air pollution is the introduction into
the atmosphere of chemicals,
particulates, and biological matter
that cause harm to humans, other
living organisms, or cause damage to
the natural environment.
Air pollutants - airborne substances
that occur in concentrations high
enough to threaten the health of
people and animals, to harm
vegetation and structures, or to toxify
a given environment (See Ahrens,
2000).
Air Pollution is measured by the
amount in 'concentration'.
What is Air Pollution?
The air that makes up our
atmosphere is almost entirely
made up of two gases (78 percent
nitrogen and 21 percent oxygen),
with a few other gases (such as
carbon dioxide and argon) in
smaller quantities.

3. Sources of Air Pollution
Natural Sources:
wind picking up dust suspended
Particles volcanic eruptions dust, ash,
gases like SO2, CO2
forest fires: smoke, ash, unburned
hydrocarbons, CO2
Vegetation: VOCs, pollen
Ocean Waves: salt particles
Anthropocentric Sources:
industry
Mills, power plant, refineries
manufacturing
particulate matter, SOx, NOx, ash
transportation
open burning of refuse
CO, NOx, VOCs, particulate matter
forest fires smoke, ash, CO2

4. The Clean Air Act requires EPA to set National Ambient Air Quality Standards for six common air pollutants.
Under the Clean Air Act, EPA establishes air quality standards to protect public health and the environment. EPA
has set national air quality standards for six common air pollutants.
(See http://www3.epa.gov/airquality/urbanair/)
Of the six pollutants, particle
pollution and ground-level ozone
are the most widespread health
threats.
EPA calls these pollutants "criteria"
air pollutants because it regulates
them by developing human health-
based and/or environmentally-
based criteria (science-based
guidelines) for setting permissible
levels. The set of limits based on
human health is called primary
standards.
The Big 6
Carbon Monoxide (CO)
created by incomplete combustion
(especially bad with older cars)
generates headaches, drowsiness,
fatigue, can result in death
Ground-level Ozone (O3)
Lead (Pb)
Nitrogen Dioxide (NO2) Oxides of Nitrogen (NOx, NO)
emitted directly by autos, industry
Particulate Matter (PM)
dust, ash, salt particles
bad for your lungs
Sulfur Dioxide (SO2) Sulfur Oxides (SOx)
produced largely through coal burning
responsible for acid rain

5. requires clear, sunny skies (since L.A.
photochemical smog requires sunlight for at one
of the key chemical reactions).
NOx + ROG + sunlight --> O3 + NO2
ROG are reactive organic gases from unburned
gasoline
NOx are oxides of nitrogen
Primary pollutants in LA smog:
CO - carbon monoxide
NO - nitric oxide
ROG - reactive organic gases (unburned gasoline)
These are mainly direct combustion products
from gasoline- or diesel-burning internal
combustion engines.
There is a significant source of ROGs from
stationary industries and small businesses.
examples include:
sulfuric acid H2SO4
can cause respiratory problems
nitrogen dioxide NO2
gives air a brownish coloration
photochemical smog
First & Secondary Pollutants
Form in the atmosphere through chemical &
photochemical reactions from the primary
pollutants
See http://apollo.lsc.vsc.edu/classes/met130/notes/chapter18/index.html

6. Effects of Air Pollution
Acid Rain
Eutrophication
Haze/Smog
Negative Effects on Wildlife
Crop and Forest Damage
Ozone Depletion
Global Climate Change

7. Photo from The Week: http://theweek.com/articles/586863/brief-history-air-pollution

8. Air Pollution in
Mexico City
"Mexico City is an omen, that jammed city
of toxic air and leafless trees may be the
first to know asphyxiation by progress. One
of the world's oldest civilizations suffers
mankind's newest affliction. Mexico City
warns the rest of the species of all that has
gone wrong with modernity's promised
millennium of happiness."
- Carlos Fuentes, 1992
http://articles.latimes.com/1989
23/books/bk-1926_1_mexico-c
breathing-fecal-dust-carlos-fuen

9. Mexico City Air Pollution History
In 1992, the United Nations
described Mexico City's air as the
most polluted on the planet.
● Many factors have contributed to
this situation: industrial growth, a
population boom (from three
million in 1950 to some 20 million
today), and the proliferation of
vehicles. More than 3.5 million
vehicles — 30% of them more
than 20 years old — now ply the
city streets.
●
● Pollution since the
early 1990s has
dropped dramatically
according to the Mexico
government studies.
http://www.idrc.ca/EN/Resources/Publications/Pages/ArticleDetails.aspx?PublicationID=740

10. Sources & Issues
● Added emissions tests
● Reduction of outdated
cars
Transportation – automobiles
account for about 90% of pollution
Personal Vehicles
● Collectivos (buses)
● Factories
● Homes
● Slum areas

11. Geographical Concerns
Geography is partly responsible for the lack of
dispersion of air pollution in Mexico City. Mexico City is
set in a valley surrounded by mountains. Located in the
crater of an extinct volcano, Mexico City is about 2,240
metres above sea level.
Depending on the pressure of the air, the dry
air from the upper layer moves downwards on
the lower layer creating a condition known as
Thermal Inversion
This acts like a stopper, trapping pollution and
provoking a reduction in visibility. The
trapped air pollution is exposed to solar
radiation making visibility difficult. The
photochemical transformation of the
pollution stimulates production of ozone and
fine particles.(See http://www.mexicocityvibes.com/air-
pollution-in-mexico-city/)
This is the same photochemical reaction
that happens in LA as both of these places
have sunlight for this reaction.
Photo from http://www.mexicocityvibes.com/air-pollution-in-mexico-
city/)

12. Major Pollution Composition & Reduction
SULPHUR DIOXIDE
NITROGEN DIOXIDE
NITRIC OXIDE
CARBON MONOXIDE
OZONE
This is a very similar
pollution composition
to LA.
(See http://www.mexicocityvibes.com/air-pollution-in-mexico-city/)

13. Actions
Hoy No Circula (No Drive Days)
Implemented in 1989 during the
time of worst air pollution in
Mexico City. Based on testing
EcoBici
Bicycle sharing system launched
in 2010.

14. Literature Cited
● http://news.harvard.edu/gazette/story/2014/10/coming-up-for-air/
● http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3230450/
● http://theweek.com/articles/586863/brief-history-air-pollution
● http://www3.epa.gov/air/basic.html
● http://www3.epa.gov/airquality/urbanair/
● http://www.cleanerandgreener.org/resources/air-pollution.html
● http://apollo.lsc.vsc.edu/classes/met130/notes/chapter18/index.html
● http://www.mexicocityvibes.com/air-pollution-in-mexico-city/
●
http://www.idrc.ca/EN/Resources/Publications/Pages/ArticleDetails.aspx?PublicationID=740
●
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● Commission on Life Sciences Staff. Biologic Markers of Air-Pollution Stress and Damage in Forests. Washington, DC, USA:
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