Now do this put-the-text-back-together activity.
This is the text (if you need help).
The brightness of light from our cities has reached such high levels that it is reducing the darkness of night. A century ago, when night-time fell, the dark of night arrived. Things are different today. A new study reports that artificial light at night is increasing around the world. Scientists say it grew by 2.2 per cent a year between 2012 and 2016. This intrusion of artificial light is causing us many problems. The International Dark-Sky Association says it, "is not only impairing our view of the universe, it is adversely affecting our environment, our safety, our energy consumption and our health".
Dr Franz Holker said artificial light is a threat to our natural environment. He called it a "pollutant that threatens nocturnal animals and affects plants and microorganisms". He added that it is affecting everything from bacteria to mammals, including humans. He said it is reshaping "entire social ecological systems". Environmentalists thought LED lights would help. However, cities are using more LED lights because they are cheaper. This is adding to the light pollution. Night-time light decreased in 16 countries, including nations at war, like Yemen and Syria.
Back to the light pollution lesson.