International Regulation of Urban Smog Since the 1940s - Air Pollution and Global Warming: History, Science, and Solutions - page 202

Ambient standards were then set for CO(g), NO 2 (g),
SO 2 (g), O 3 (g), lead, and total suspended particulate
matter. The government also provided incentives to
relocate industry out of Mexico City (1978), introduced
low-leaded gasoline into the fleet (1986), and began to
require vehicle inspections (1989).
In 1988, Mexico passed its first emission standards
for light- and heavy-duty vehicles. These standards
applied to 1993 model cars. The light-duty standards
were made more stringent, in line with U.S. Tier I stan-
dards in 2001. Since 2004, such standards have followed
amix of U.S. and EU standards. In 2006, new emission
standards for heavy-duty trucks and buses were imple-
mented based on U.S. 2004 and Euro 4 standards for
2008 model vehicles (DieselNet, 2011).
Ozone levels in Mexico City exceeded national stan-
dards during 324 days in 1995. That year, Mexico initi-
ated a 5-year National Environmental Program (1996-
2000) designed to clean up air pollution in Mexico City.
The government also passed a tax incentive program
for the purchase of pollution control equipment. As a
result of these measures and the phase-out of older cars
between 2000 and 2006, ozone mixing ratios decreased
by about 24 percent. However, mixing ratios for half
the hours of 2006 were still above 83 ppbv, which com-
pares with half the hours exceeding 108 ppbv in 2000
(Sanchez and Ayala, 2008).

would remain similar to that of gasoline alone. Ethanol
for the project was produced primarily from sugarcane.
Because the market price of an ethanol-gasoline blend
washigher than that of pure gasoline, the program
required government subsidies. When gasoline prices
fell and sugarcane prices increased in the late 1980s,
ethanol prices rose sharply, and the program disinte-
grated. In fact, by 1997, only 1 percent of new cars sold
in Brazil used ethanol. In 1999, the Brazilian govern-
ment revived the alcohol fuel program by encouraging
the replacement of taxis and government vehicles with
new vehicles that ran on 100-percent ethanol. Although
the use of ethanol fuel instead of gasoline reduces the
emission of aromatic hydrocarbons in smog, it increases
the production of acetaldehyde (Section 4.3.7), gener-
ally leading to greater ozone and PAN formation.
A damaging by-product of the sugarcane ethanol
program in Brazil is the annual burning of sugarcane
fields to facilitate manual harvesting of the sugarcane.
Forexample, Brazil's largest sugarcane-producing
state, Sao Paulo, has more than 100 ethanol mills and
sugarcane plantations. Annual burning of the sugar-
cane in the state occurs over more than 2 million acres,
creating extended plumes of smoke (Figure 8.14) that
choke rural communities and contribute to pollution
overcities. The use of mechanized harvesting can elim-
inate the need for cane burning, and many ethanol mills
in the state of Sao Paulo have agreed to convert to
mechanization by 2017. However, burning continues,
and other states have not followed suit.
In 1993, Brazil adopted its first vehicle emission stan-
dards based on EU standards. It strengthened the stan-
dards in 2002, effective from 2006 to 2009, based on
Euro 3 and 4 light-duty vehicle standards, and again
in 2009, effective from 2013 to 2015, based on Euro
5standards. Brazil does not permit diesel engines in
passenger cars, so the country did not originally have
adiesel vehicle emission standard. However, because
Brazil's standards are used by adjacent South Ameri-
can countries that do allow diesel passenger cars, Brazil
set diesel emission standards in 2002. Brazil's vehicle
emission regulations cover heavy-duty vehicles as well
(DieselNet, 2011).

8.2.14. Brazil
Most of Brazil is covered by the Amazon rainforest,
which makes up 30 percent of the world's remaining
tropical forests. Sao Paulo, Brazil's largest city, is the
second most populated metropolitan area in the Ameri-
cas after Mexico City. Air pollution in Sao Paulo results
from a large number of high-emitting automobiles, poor
road systems, low fuel prices, and local burning of sug-
arcane fields. Electric power production is not a major
source of air pollution in Brazil because about 95 per-
cent of the country's electricity is obtained from hydro-
electric power. Instead, a large source of air pollution
in Brazil is the burning of parts of the Amazon rainfor-
est to clear land for agriculture and grazing ( biomass
burning ) and the annual burning of many agricultural
fields.
In 1975, Brazil started an alcohol fuel program ,the
Brazilian National Alcohol Program, to reduce Brazil's
reliance on imported fuel following the worldwide spike
in oil prices in 1973. The program ensured that all
gasoline sold in Brazil contained 22 percent anhydrous
ethanol and that the price of the ethanol-gasoline blend

8.2.15. Chile
The air in Santiago, Chile, ranks among the most pol-
luted in the world, especially in terms of particulate
matter. The pollution is due to vehicles, industrial emis-
sions, unpaved road dust, and dust from eroded land.
The city, nestled in a valley, frequently experiences a