Britannica Student Encyclopedia - 2010

By the early 1990s tens of thousands of

lakes had been destroyed by acid rain.

The problem has been most severe in

Norway, Sweden, and Canada. Damage

from acid rain is not limited to the

countries that produce the pollution.

This is because winds carry the pollution

around the globe.

Despite much discussion between many

countries, there is still no clear solution

to the problem. The chief reason is that

it is expensive to control the pollution.

However, since the damage from acid

rain to the environment is permanent,

the environmental costs are greater.

Acne

Most teenagers and some adults experience

a skin condition called acne. Some

cases of acne are very mild and go away

without leaving any signs. Others are

more serious and may cause scarring.

Boys are more likely than girls to have

severe acne.

Lesions (abnormal bumps or spots) on

the skin are the main symptom of acne.

Acne lesions are commonly known as

pimples. They occur especially on the

face and neck.

Acne is caused by changes inside the

body that affect the skin. These changes

occur naturally as a boy or girl reaches

puberty, or matures. At that time the

body produces more of chemicals called

Acid rain can be very damaging to trees

and other plants. The branch on the left has

been affected by acid rain. It looks much

different than the branch on the right.

18 Acid Rain BRITANNICA STUDENT ENCYCLOPEDIA

 

hormones. Some of those hormones

speed up the skin’s production of oil.

The extra oil clumps together with dead

skin cells to clog pores, or tiny openings

in the skin. As the oil gland under a

clogged pore makes more oil, the pore

swells up to form a pimple.

There is very little a person can do to

prevent acne. However, there are treatments

for clearing up acne and ways of

preventing acne from getting worse.

Washing the skin twice a day with a

mild soap can be helpful. This removes

some oil and dead skin cells that help to

clog skin pores.

In some cases a doctor may prescribe

medicine to treat infections caused by

acne. Doctors may also suggest medicated

lotions or creams that can be put

on the skin.

#More to explore

Hormone • Skin

Acropolis

Ancient cities were often built around a

fortress on top of a hill. When a city

spread to the area below, the high part

came to be called the acropolis, which

means “city at the top” in Greek. The

best-known acropolis is in Athens,

Greece.

The buildings of the Athens Acropolis

were made mostly of white marble. Parts

of some of the buildings, including a

temple called the Erechtheum, are still

standing today. The Erechtheum had a

porch with marble columns in the shape

of female figures.

The most famous surviving building is

the Parthenon. The Parthenon was built

almost 2,500 years ago and was dedicated

to the goddess Athena. Athens was

later ruled by Christians who made the

Bumps called pimples are the main sign of

acne.

The ruins of the Parthenon stand out on the

Acropolis in Athens, Greece.

BRITANNICA STUDENT ENCYCLOPEDIA Acropolis 19

 

Parthenon a church. In the 1400s Turkish

forces took control of the Acropolis

and made the Parthenon an Islamic

mosque. In 1687, during a war, some

gunpowder stored there exploded,

destroying the middle of the building.

In 1801 a British diplomat named Lord

Elgin took many sculptures and carved

panels from the Parthenon and brought

them to England. They were put on

display at the British Museum. The

Greek government, however, asked for

their return to Greece. The sculptures

remained on display while the dispute

continued into the 21st century.

#More to explore

Athena • Athens

Acupuncture

Acupuncture is an ancient Chinese form

of healing. It involves piercing the skin

with thin needles to relieve pain. Today

acupuncture is also popular in Europe,

the Americas, and Australia.

Modern doctors accept that acupuncture

can control pain and nausea. Some doctors

recommend acupuncture along with

regular medical treatments for such ailments

as asthma, high blood pressure,

indigestion, and stress. Doctors in China

have even used acupuncture instead of

drugs to stop pain during surgery.

People who practice acupuncture must

take courses to learn how to do it correctly.

In many places only medical doctors

may perform acupuncture.

During treatment the patient lies on a

table while the acupuncturist sticks special

needles into certain points on the

body. The needles are made of metal and

are about as thick as a human hair. They

normally go less than 0.5 inch (1 centimeter)

into the skin. There are hundreds

of possible points where the needles can

be stuck, each with a different effect.

Doctors are not sure how acupuncture

works. Some think that the needles

cause the body to produce pain-killing

chemicals. Others think that the needles

block pain signals from traveling along

the nerves to the brain. Some think that

acupuncture acts like a placebo—a treatment

that works only because patients

believe it will.

Adams, Abigail

Abigail Adams was the wife of President

John Adams and the mother of Presi-

A woman receives an acupuncture

treatment.

20 Acupuncture BRITANNICA STUDENT ENCYCLOPEDIA

 

dent John Quincy Adams. Her reading