1 . If you’re worried about your receding hairline (后退的发际线) and you live in a city, you might want to consider moving, as scientists have found exposure to high levels of air pollution may be linked to retention.

New research presented at the European Academy of Dermatology and Venereology (EADV) Congress in Madrid found particulate matter (PM) (颗粒物), which is present in polluted air, could impact both hair growth and retention.

The team took cells from the base of hair follicles (毛囊) and then exposed them to the polluted air. They used various concentrations of PM10, and 24 hours later, they tested the samples to detect whether specific hair-growth proteins in the cells had changed at all.

Researchers found that the presence of PM10 decreased levels of the protein responsible for hair growth — beta-catenin — and morphogenesis, the biological process that causes an organism to develop its shape. According to the study, the levels of three other proteins which are responsible for hair growth and hair retention — cyclin D1, cyclin E and CDK2 — were also decreased.

This meant that the greater the level of pollutant, the greater the decrease in proteins was found.

This is one of the first studies to look at the link between pollution and baldness (秃头).

Hyuk Chul Kwon from the Future Science Research Centre in South Korea said: “While the link between air pollution and serious diseases, such as cancer, are well established, there is little to no research on the effect of particulate matter exposure on the human skin, and hair in particular. And our research explains the mode (模式) of action of air pollutants on human hair follicle cells, showing how the most common air pollutants lead to hair loss.”

1. What does the underlined word “retention” in Para 1 refer to?

A．Hair cells.	B．Hair loss.
C．Hair growth.	D．Hair-growth proteins.

2. What can we learn from the passage?

A．Air pollution can increase levels of hair-growth proteins.

B．There’s only one protein that is responsible for hair growth.

C．Polluted air has no direct impact on hair growth or retention.

D．The more serious air pollution, the more likely you’re to lose your hair.

3. What did Hyuk Chul Kwon think of the research?

A．Meaningful.	B．Negative.
C．Unimportant.	D．Objective.

4. What’s the main idea of the passage?

A．The solutions to air pollution.

B．The growth mechanism of hair.

C．The impact of air pollution on health.

D．The close link between air pollution and hair loss.