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Dramatic reduction in light pollution during lockdown, Star Count reveals

6 April 2021

  • Light pollution levels were much lower at the start of 2021 compared to previous year, finds CPRE, the countryside charity
  • Launched to mark International Dark Skies Week, CPRE’s annual Star Count shows a 10% drop in severe light pollution compared to 2020, and the largest percentage of truly dark skies since 2013
A map of the UK with light points shown across it, especially around urban areas
2021 Star Count results | CPRE

A nationwide Star Count conducted in February has revealed a significant drop in light pollution levels across the UK. The annual citizen science project asks people to count the number of stars they see in the Orion constellation.

Nearly 8,000 counts were submitted between 6 and 14 February 2021, with 51% of people noting ten or fewer stars, indicating severe light pollution. This compares to 61% during the same period last year. 30 or more stars indicates truly dark skies and were seen by 5% of participants – the highest figure since 2013.

Lockdown is the most likely reason for this change, with reduced human activity resulting in quieter than usual urban areas. Similar patterns have been found with air pollution, which has also dropped across the country.

The results, which can be seen in this stunning interactive map, have been launched to mark International Dark Skies Week, run by the International Dark-Sky Association (IDSA), which raises awareness on the impacts of light pollution.

Light pollution can negatively affect human health and wildlife by disturbing animals’ natural cycles and behaviours. Badly designed, wasteful light also contributes to climate change and obscures our connection to the Universe.

Therefore, CPRE and IDSA want to combat light pollution through strong local and national policies, while also protecting and enhancing existing dark skies. This involves putting the right light in the right places, such as LED lights that only illuminate where we walk, and turning off lights in places like office buildings when they’re unoccupied.

CPRE and IDSA hope this fall in people experiencing the most severe light pollution – an unintended but positive consequence of lockdown – continues long after coronavirus restrictions are lifted so more people can experience the wonder of a truly dark sky.

Crispin Truman, chief executive of CPRE, the countryside charity, said:

‘It’s been an absolutely stellar year for Star Count. We had three times as many people taking part compared to previous years and I’m delighted to see severe light pollution in the UK appears to have fallen. It’s likely this is an unintended positive consequence of lockdown, as our nighttime habits have changed. Let’s hope we can hold onto some of this achievement as we come out of lockdown.

‘Looking up at a starry night sky is a magical sight and one that we believe everyone should be able to experience, wherever they live. And the great thing is, light pollution is one of the easiest kinds of pollution to reverse – by ensuring well designed lighting is used only where and when needed, and that there is strong national and local government policy.’

Ruskin Hartley, Executive Director of the International Dark-Sky Association, said:

‘IDA is delighted to learn of the turnout for this year’s Star Count, and congratulates CPRE for another successful event. Thousands of people looked through their windows or gazed from their gardens at the night sky. The results are encouraging because light pollution levels appear to be falling, but it still remains an issue.’

‘We believe that solving the problem of light pollution begins with knowing the problem exists. For many people, participating in Star Count during lockdown may have, for the first time in a long while, have been their first encounter with a dark night sky.

‘As realisation turns to action, we look forward to working with CPRE to bring attention and resources to tackling night blight, bringing dark skies to more of the UK.’

For further information, case studies or to interview a spokesperson, please contact: Jessica Rowley, CPRE Media Lead – Consumer, 07474 891 023,

Notes to editors

Table 1: Full results table

Full results of Star Count 2021
Stars counted Number %
0>5 904 11.5
6>10 3098 39.5
11>15 1905 24.3
16>20 901 11.5
21>25 444 5.7
26>30 180 2.3
>30 412 5.3
Total 7845 100

Table 2: Yearly Star Count results

Number of stars counted within the constellation of Orion

Yearly Star Count results
Year 0 > 5 6 > 10 11> 15 16 > 20 21 > 25 26 > 30 31 >
2007 14% 40% 24% 12% 6% 2% 2%
2011 16% 43% 22% 11% 5% 2% 1%
2012 14% 39% 23% 13% 6% 3% 2%
2013 17% 37% 22% 10% 6% 3% 5%
2014 20% 39% 21% 9% 5% 3% 4%
2019 15% 42% 22% 11% 7% 2% 2%
2020 18% 43% 22% 9% 4% 1% 3%
2021 12% 40% 24% 12% 6% 2% 5%

NB: without decimals in this overall tracking table, it looks like 52% saw <10 stars, but that’s because we’ve rounded up here (see table 1 for the more accurate result, which is 51%).

About Star Count

Star Count is an annual citizen science project from CPRE, the countryside charity, and the British Astronomical Association. From 6-14 February 2021, the public were asked to look heavenwards during a clear night and count how many stars within Orion they can spot.

Results from Star Count help make a map of where star-spotters are enjoying deep, dark skies and where people’s views are affected by light pollution. By showing on a map where light pollution is most serious, we can work nationally and with local councils and others to decide what to do about it.

Find out more on the CPRE website.

About International Dark-Sky Association

The International Dark-Sky Association (IDA) is the recognized authority on light pollution and is the leading organization combating light pollution worldwide. Their vision is of a night sky, filled with stars, that is celebrated and protected around the world as a shared heritage benefiting all living things.

Formed in 1988, they now have 66 chapters operating in 17 countries; have designated 170 International Dark Sky Places, protecting over 110,000 sq km around the globe; made 1,000+ dark sky certified lighting fixtures commercially available, and supported 23 dark sky communities in adopting strong lighting policies.