2 . Noise pollution has a long-term effect on tree populations that may persist even after the sources of noise are removed, according to research published Wednesday.

Man-made noise from industry and the building of infrastructure such as roads and pipelines has increased greatly since the middle of last century. While previous research has documented the short-term effect noise has on tree populations as it scares off pollinators (传粉者) such as insects and animals, few studies have covered the long-term effect.

Researchers in the United States looked at tree populations in New Mexico that had been “hearing”a high level of man-made noise for 15 years. They found 75 percent fewer pinyon pine seedlings (矮松苗) in noisy places than quiet ones.

Then they looked at other places in New Mexico, where sources of noise had recently been added and then removed, and examined how populations recovered. The team assumed that populations of the trees — in this case pinyon seedlings — would recover as the pollinators would return to the places once the noise had disappeared. Instead, they found a long-term drop in seedling numbers as the birds refused to revisit the places.

“The effects of human noise pollution are growing into these woodland communities,” said Clinton Francis, lead researcher from California Polytechnic State University. “What we’re seeing is that removal of the noise doesn’t necessarily immediately result in a recovery of ecological function.”

Jennifer Phillips, co-author of the research, said the findings showed how the effect of noise pollution could put pollinators off even after the noise is removed. “Animals like the birds that are sensitive to noise learn to avoid particular areas.” said Phillips. “It may take time for animals to come back to pollinate trees in these previously noisy areas, and we don’t know how long that might take.”

As governments continue to face growing evidence of the damage to nature caused by urbanization (城市化), Phillips held that the influence of noise pollution should also be factored into planning decisions.

4 . 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.”