Why are astronomers concerned about light pollution?

Light pollution is very much a concern across the globe, something astronomers and skywatchers are trying to bring attention to. It not only takes away the right to enjoy the night skies and explore the celestial bodies with the naked eye but also affects the circadian rhythm of humans and wildlife.

Have you seen a sky spangled with stars winking at you from light years away? Have you ever spotted the Milky Way?

Well with the amount of artificial light strewn across the sky. it is a fact that dark skies that bring out the beauty of the cosmos are a rarity.

Light pollution is very much a concern across the globe, something astronomers and skywatchers are trying to bring attention to. It not only takes away the right to enjoy the night skies and explore the celestial bodies with the naked eye but also affects the circadian rhythm of humans and wildlife. So what is light pollution?

Light Pollution

Across the world, people have to deal with the nighttime glow caused by artificial light. This has been affecting humans, wildlife, and the environment equally. There is a global movement to reclaim the dark sky and reduce light pollution.

Sources of light pollution

The major cause of light pollution is misdirected light which scatters out into the open sky caused by human activities. From street lights to lights from buildings, boats, and outdoor advertising to illuminated sporting venues, every misdirected light leads to light pollution. High levels of sky glow mean fewer chances of seeing enough celestial bodies in the sky.

The circadian rhythm and light pollution

Artificial light can affect the circadian rhythm in both humans and animals. The circadian rhythm is the natural process regulating the sleep-wake cycle. The production of the hormone melatonin is linked to this. This sleep-inducing hormone gets released when it is dark. The presence of light inhibits it. If the ambient light is high at night, then it lowers the production of melatonin and leads to sleep deprivation, stress, fatigue, and anxiety.

Animal behaviour and light pollution

It has been proven that wildlife has also been affected badly by light pollution. The animal behaviours such as migration patterns and wake-sleep habits of animals have been affected. Birds and sea turtles have been found to lose their way and get confused due to the presence of increased ambient light. Light also affects the circadian rhythm of animals.

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The river as a dumpyard

The Mekong is one of the longest rivers in the world, cutting across several Asian regions from Tibet and China to Thailand and Cambodia. But spanning a large area means the threats it faces are just as huge. What are they? Come, let's find out.

Waste generated in any region is disposed of in many ways, including being dumped at landfills. (Only a minuscule fragment of waste is recycled globally.) Some countries export their waste. Several Asian countries have been taking in plastic waste from such countries, without really being equipped to handle waste disposal safely. In addition, these Asian countries have their own waste to deal with. The waste in landfills reach rivers and oceans through winds, rains, and drains. One such river is the Mekong. Painfully, three "of the worst six plastic polluting countries China, - Thailand, and Vietnam - have a presence in Mekong", meaning the quantum of waste this river takes in is huge and increasing. The pandemic, with its masks, plastic sanitiser containers, take-away plastic boxes, etc., has exacerbated the situation. And, this is of grave concern.

The Mekong is a treasure trove of biodiversity - several species of plants, birds, reptiles, and fishes call the river and its surrounding regions home. But in the current scenario, rubbish is finding its way into the water, endangering wildlife. Animals and birds are in danger of being affected by plastic debris through entanglement or ingestion. There have been instances of dead whales "turning up in Thailand and Indonesia with many kilograms of plastics in their stomachs". It is not just wildlife that's affected. When humans consume creatures such as fish, we end up consuming plastic, which has the potential to cause serious health problems such as cancer. Since rivers drain into larger waterbodies such as seas (the Mekong mixes with the South China Sea) and oceans, the pollution they carry is transferred too.

An increase in the pollution of waterbodies is an indication of increasing pollution on land. And a grim reminder that unless we change our lifestyles to make this planet greener, we are likely to face the negative consequences of our own actions.

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What is Air Quality Index?

Air Quality Index indicates how safe or polluted the air is, and the health concerns involved

The air quality deteriorates throughout India in October and November every year due to festivals, among other reasons. Post-Deepavali, Air Quality Index (AQI) is the most-talked about.

What is AQI?

The AQI is the yardstick used to report how clean or polluted the air is. It is used to help people know how the local air quality impacts their health. These indices indicate whether the amount of nitrogen dioxide, carbon monoxide, and sulfur dioxide in the air exceeds the criteria set by the World Health Organisation (WHO) or not.

How is AQI calculated?

 To calculate AQI, an air monitor and an air pollutant concentration over a specified averaging period is needed. The results are grouped into ranges, and each range is assigned a descriptor, a colour code, and a standardised public health advisory.

The AQI categories are - Good (0-50), Satisfactory (51-100), Moderately polluted (101-200), Poor (201-300), Very Poor  (301-400), and Severe (401-500) - with colour coding ranging from green to dark red.

What are AQI pollutants?

India launched the National Air Quality Index Standard (NAQI) on September 17, 2014. The National Air Monitoring Program (NAMP) covering 240 cities in the country is operated by the Central Pollution Control Board (CPCB).

In India, the AQI keeps a tab on eight major air pollutants in the atmosphere - Particulate Matter (PM10), Particulate Matter (PM2.5), Nitrogen Dioxide (NO2), Sulphur Dioxide (SO2), Carbon Monoxide (CO), Ozone (03), Ammonia (NH3), and Lead (Pb).

Health risks

An increase in AQI increases public health risks, especially affecting children, elderly, and individuals with respiratory or cardiovascular issues.

During these times, governments generally urge people to reduce physical activity outdoors, or even avoid going out altogether. The use of face masks such as cloth masks are also recommended.

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What are ways to reduce pollution in school?

New research suggests that simple measure that can be implemented in many schools has a telling influence on air quality. Schools form an integral part of childhood. Worldwide, an estimated 10 million students spend 30% of their daily lives at schools. Out of their duration at school, 70% of the time is spent indoors. Low air quality in such environments leave the children vulnerable to many respiratory diseases, behavioural problems, affect lung and brain health, and even lead to an increased risk of cancer.

Poor air quality

Many schools in our country breach the limits set by the World Health Organisation for air quality. In such a climate, enhancing the surroundings in whatever little way helps in the overall scheme of things. There's good news, however, as new research suggests that simple measures that can be implemented in many schools has a telling influence on air quality.

In a paper titled "Investigation of air pollution mitigation measures, ventilation, and indoor air quality at 5 three schools in London", researchers from the University of Surrey listed their findings. The paper, published in the journal Atmospheric Environment, is available online and will be part of the 1 ? issue dated November 15, 2022.

Simple initiatives

Researchers investigated if putting up a green screen along the perimeter of the school, installing air purifiers in classrooms, and organising street initiatives during drop-off and pick-up hours had an effect in classrooms and playgrounds. They did this by working with a select number of London schools.

Installation of air purifiers in classrooms reduced indoor pollution concentrations by up to 57%. The street initiatives, which forces motor vehicles to not ply on roads with schools at the start and end of school days, reduced the particle concentrations by up to 36%.

Based on wind conditions, green screens at school boundaries were also effective. In the best case, they were able to reduce some of the most dangerous outdoor particle levels from the roads by up to 44%.

As ensuring that schools have green perimeters, lesser vehicular traffic during pick-up and drop-off, and installing air purifiers in classrooms are simple and affordable techniques, these can be replicated everywhere. While their effectiveness would have to be studied further, methods like these will eventually ensure that schools remain safe spaces to learn.

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Noise pollution, especially that's due to road traffic, is a widespread problem in cities around the world. At a time when the impact of these on children isn't well understood, a new study conducted at 38 schools in Barcelona, Spain suggests that traffic noise at schools has a detrimental effect on children's cognitive development. The study was led by the Barcelona Institute for Global Health and the findings have been published in PLOS Medicine in June.

Attention and working memory

 The study covered 2.680 children between seven and 10 years of age. To assess the impact of traffic noise on cognitive development, researchers focussed on attention and working memory-two abilities that develop rapidly in that age group and are essential for learning. While attention corresponds to selectively attending to specific stimuli, working memory refers to the system that enables us to hold information in the mind and manipulate it during a brief period of time.

Over a 12-month period in 2012 and 2013, the field work of the study saw participants complete cognitive tests four times. By doing this, they were not only able to assess working memory and attention, but could also study their evolution over time. Noise measurements were taken in front of the 38 participating schools over the same period.

Slower progression

At the end of the study period, the findings clearly showed that the progression of working memory and attention was comparably slower in students who attended schools with higher levels of traffic noise. This supports the hypothesis that during childhood external stimuli like noise can affect the rapid process of cognitive development that takes place before adolescence.

Thus, the effects of transport on children's cognitive development not only includes schools exposed to aircraft noise and schools exposed to traffic-related air pollution, but also schools exposed to road traffic noise. Further studies on road traffic noise and their effects on children in other populations and cities are necessary to find out if these initial findings can be extrapolated to other scenarios.

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