Air pollution is the result of excessive introduction of substances like gases, particles, or biological measures to our atmosphere. In that case, the air we are breathing in every second is almost always polluted nowadays, due to our increasing activities.
Thus, you know that almost every single activity we do in this modern world is polluting the air. The fact is, level of pollution entering your lungs is increasing even more when you are living in more active areas like big cities or industrial areas.
That is a fact that we cannot ignore, for sure, and we also know that air pollution may cause disasters to other living things on earth. But in this article we are not going to talk about that. In this article, we are going to talk about something more abstract: how pollution makes our night sky ‘uglier’.
Signs Of Pollution
We know that our atmosphere is polluted, but how can we detect it without sophisticated tools? There are so many ways we can measure air pollution naturally. Especially when the pollution level is so high, we can use our senses to do it.
Many times we can smell and see the pollution by ourselves without sophisticated tools. You know what Sulphur smells like, don’t you? You also know what smoke looks like, don’t you? Then you can already detect air pollution.
You might have noticed that the air in big cities are not as ‘clear’ and ‘fresh’ as the air in secluded areas like forests, beaches, and mountains. The ‘clearness’ and ‘freshness’ is the easiest way to notice the presence of airborne materials.
However, this method is only applicable when the pollution has distinctive look and or smell. Sometimes, air pollution doesn’t show its presence to us because it doesn’t have distinctive smell and look. In example, carbon monoxide pollution in the air.
Not only that, most of the times we cannot detect the pollution level by ourselves because it is not that high. Because of the nature of air, airborne pollutants are dispersed in the atmosphere as quickly as possible. So, how do we know that the place we are living in is polluted or not?
Visibility
Our sense of smell is limited, so is our sense of sight. However, our sense of sight can detect things much further than our sense of smell. You can see stars but you surely cannot smell those burning gasses up in the sky.
That’s why, we can rely on our sight more in this case by looking for signs of haze. What is haze? Haze is atmospheric phenomenon in which airborne materials can obscure the clarity of our sights. Smoke and smog are the examples.
But how can we measure air pollution from haze? It is so easy to do, actually. Air pollution may cause a haze that affects how far we can see. The presence of haze can also affect our ability to see colors and texture of things.
In other words, we can measure air pollution in an area by how clear and detailed texture and color of it when we see it from afar. In example, The National Park Service (NPS) keeps track of the visibility condition in areas they cover to monitor air pollution.
“In western parks and wilderness areas, the average distance a visitor can see has improved from 90 miles to 120 miles over the same period. Unfortunately, the clarity of park views is still affected by air pollution in virtually all national parks across the country,” as stated in the site.
Sunlight And Haze
How can actually the presence of haze affect our ability to get detailed view of something? Air pollution is basically the presence of airborne tiny particles in the atmosphere, and those particles are actually ‘visible’ to our eyes.
What means by ‘visible’ is that it can reflect sunlight into our eyes. As mentioned above, those tiny particles are scattering in the atmosphere, creating some kind of layers that prevents us to see clearly into the thing we are looking at.
Their presence can affect our ability to see an object clearly in two ways. First is by blocking sunlight’s reflection of an object to reach our eyes in two ways. Second is by reflecting light brighter than the object we are seeing and thus scattering the light spectrum we should have received from the object’s reflection.
“Some types of particles scatter more light, especially when it is humid. Haze is mostly caused by air pollution from human activity including industry, power generation, transportation, and agriculture,” as stated in NPS site.
The more particles presence in the air between us and the object, more light that the object reflects to our eyes is scattered and blocked. We can see it from air photos of polluted cities like Mumbai and Beijing. When unedited, those pictures show less clarity than other areas.
Air Plus Light Pollution
Okay, that’s how we find out whether a city is polluted or not. But how do we find out whether the city we are living in is polluted or not without the needs to leave the city and see it from afar? There is a way that you can immediately do: look up.
Just like how airborne particles can prevent us to see an object clearly, it can also prevent us to see the sky clearly especially during night. But there are more than airborne particles in this case that prevents us to see the night sky clearly.
As we have talked before about light pollution in our previous articles, the presence of airborne pollutants makes it worse. Light pollution alone interferes with our ability to see clear night sky because our eyes is exposed to artificial lights that prevents dimmer light from the stars to reach our eyes.
Combined with air pollution that prevents those dim lights like mentioned above, it means that in bright-and-polluted cities we are harder to see stars compared to other places. That’s not it, because the air borne materials can also reflect the artificial lights from the earth back to us.
Don’t you notice that the color of night sky in big cities is usually more reddish than more natural places? That’s what you get from the combination of light pollution and air pollution. The reddish color is actually the reflection of artificial lights from the city that’s being reflected back to us.
Well, we all know the health and environmental risks that air pollution can cause us. In addition, now you also know that it prevents us from seeing those beautiful constellations too. So, are we going to keep on polluting our atmosphere?
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