Air pollution mitigation can reduce the brightness of the night sky in and near cities
We wanted to briefly draw attention to a paper published last week in Nature Scientific Reports: https://www.nature.com/articles/s41598-021-94241-1. We build on existing work connecting air quality with skyglow formation through a combination of radiative transfer theory and simulations, plus a field experiment simulating a persistent reduction in air pollution during which we measured a decrease in skyglow consistent with our calculations.
We concluded that reductions in air pollution from any cause, whether due to short-term weather changes or persistent efforts to improve air quality, would result in the kinds of skyglow reductions indicated by our models and supported by our field observations. The result adds a further benefit to reducing air pollution beyond the well-known public health improvements seen to follow clearing of polluted air. But as a means of improving night skies over cities, we stress in the paper that air pollution reductions should not be relied on as an alternative to conventional light pollution reduction methods such as proper outdoor lighting design.
To reduce skyglow over cities, reducing air pollution should be seen as a tool that enhances rather than replaces techniques that we know work quite well. Using outdoor light at night wisely, including a diminished dependence on outdoor lighting through advances in lighting technology, remains the cornerstone of any effort to make meaningful improvements to urban night skies.
Miro Kocifaj (Slovakia) and John Barentine (USA)