India’s Air Pollution Plummets in COVID-19 Lockdown
India is home to 21 of the world's 30 most polluted cities, but recently air pollution levels have started to drop dramatically as the second-most populated nation endures the second week of a 21-day lockdown amidst coronavirus fears, according to The Weather Channel.
While the complete shutdown of India's economy was designed to stop the spread of COVID-19, it is having an ancillary health benefit of clearing the air that millions of people were choking on, according to CNN. As vehicles stay off the road, construction is put on hold, and factories stop production, the levels of microscopic particulate matter, or PM 2.5, start to drop.
"It is true that pollution levels are going down and will continue to be lower as a result of lockdown," Pawan Gupta, senior scientist at the Earth Sciences of Universities Space Research Association at NASA's Marshall Space Flight Center, told Earther in an email.
Recent heavy rains in the north and west of the country have also helped the country's pollution levels, Gupta added. "Rain is a very effective aerosol removal process from the atmosphere and can bring down particulate matter values," he said.
Since the March 25 lockdown that forced 1.3 billion Indians to stay home, air quality in New Delhi, usually the worst in the world, has dropped to "satisfactory" levels. The lockdown order shut down offices, schools, movie theaters, malls, markets and "non-essential" service providers. All modes of public transport such as metro trains, buses, inter-state trains and domestic and international flights for civilian movement have also been stopped, according to Quartz.
The effect of the lockdown has been dramatic. In New Delhi, where flights have been diverted because smog shrouded the airport, the air pollution levels have dropped 71 percent in just one week. On March 20, the air had an unhealthy 91 micrograms per cubic meter of PM2.5. On March 27, just a couple days into the lockdown, that level fell to 26 micrograms per cubic meter. Anything above 25 is considered unsafe, according to the World Health Organization, as CNN reported.
"I have not seen such blue skies in Delhi for the past 10 years," said Jyoti Pande Lavakare, the co-founder of Indian environmental organization Care for Air, and author of upcoming book Breathing Here is Injurious To Your Health, to CNN. "It is a silver lining in terms of this awful crisis that we can step outside and breathe."
Data from the Central Pollution Control Board of India's Environment Ministry also showed a 71 percent decrease in nitrogen dioxide levels. Mumbai, Chennai, Kolkata and Bangalore have also recorded a drop in these air pollutants, according to CNN. In Mumbai, the financial capital, air quality levels in March 2019 averaged 153 on the Air Quality Index, which ranks as unhealthy to breathe, according to Reuters. New Delhi averaged 161 last March.
The tops of skyscrapers were visible and some residents told Reuters they could spot more stars than usual.
"The air quality is likely to slip into 'good' category soon. It is due to reduced vehicular traffic and rise in temperature," said Kuldeep Srivastava, who heads the regional meteorological center at the Indian Meteorological Department, to The Weather Channel.
However, it is important to remember that this is a temporary reprieve that will return if industry and vehicular traffic return once the lockdown is over.
As for its effect on the climate crisis, The Weather Channel reported that the World Meteorological Organization issued a statement that read: "Efforts to control the coronavirus pandemic have reduced economic activity and led to localized improvements in the air quality. But it is too early to assess the implications for concentrations of greenhouse gases, which are responsible for long-term climate change."
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The ghoulishly named ogre-faced spider can "hear" with its legs and use that ability to catch insects flying behind it, the study published in Current Biology Thursday concluded.
"Spiders are sensitive to airborne sound," Cornell professor emeritus Dr. Charles Walcott, who was not involved with the study, told the Cornell Chronicle. "That's the big message really."
The net-casting, ogre-faced spider (Deinopis spinosa) has a unique hunting strategy, as study coauthor Cornell University postdoctoral researcher Jay Stafstrom explained in a video.
They hunt only at night using a special kind of web: an A-shaped frame made from non-sticky silk that supports a fuzzy rectangle that they hold with their front forelegs and use to trap prey.
They do this in two ways. In a maneuver called a "forward strike," they pounce down on prey moving beneath them on the ground. This is enabled by their large eyes — the biggest of any spider. These eyes give them 2,000 times the night vision that we have, Science explained.
But the spiders can also perform a move called the "backward strike," Stafstrom explained, in which they reach their legs behind them and catch insects flying through the air.
"So here comes a flying bug and somehow the spider gets information on the sound direction and its distance. The spiders time the 200-millisecond leap if the fly is within its capture zone – much like an over-the-shoulder catch. The spider gets its prey. They're accurate," coauthor Ronald Hoy, the D & D Joslovitz Merksamer Professor in the Department of Neurobiology and Behavior in the College of Arts and Sciences, told the Cornell Chronicle.
What the researchers wanted to understand was how the spiders could tell what was moving behind them when they have no ears.
It isn't a question of peripheral vision. In a 2016 study, the same team blindfolded the spiders and sent them out to hunt, Science explained. This prevented the spiders from making their forward strikes, but they were still able to catch prey using the backwards strike. The researchers thought the spiders were "hearing" their prey with the sensors on the tips of their legs. All spiders have these sensors, but scientists had previously thought they were only able to detect vibrations through surfaces, not sounds in the air.
To test how well the ogre-faced spiders could actually hear, the researchers conducted a two-part experiment.
First, they inserted electrodes into removed spider legs and into the brains of intact spiders. They put the spiders and the legs into a vibration-proof booth and played sounds from two meters (approximately 6.5 feet) away. The spiders and the legs responded to sounds from 100 hertz to 10,000 hertz.
Next, they played the five sounds that had triggered the biggest response to 25 spiders in the wild and 51 spiders in the lab. More than half the spiders did the "backward strike" move when they heard sounds that have a lower frequency similar to insect wing beats. When the higher frequency sounds were played, the spiders did not move. This suggests the higher frequencies may mimic the sounds of predators like birds.
University of Cincinnati spider behavioral ecologist George Uetz told Science that the results were a "surprise" that indicated science has much to learn about spiders as a whole. Because all spiders have these receptors on their legs, it is possible that all spiders can hear. This theory was first put forward by Walcott 60 years ago, but was dismissed at the time, according to the Cornell Chronicle. But studies of other spiders have turned up further evidence since. A 2016 study found that a kind of jumping spider can pick up sonic vibrations in the air.
"We don't know diddly about spiders," Uetz told Science. "They are much more complex than people ever thought they were."
Learning more provides scientists with an opportunity to study their sensory abilities in order to improve technology like bio-sensors, directional microphones and visual processing algorithms, Stafstrom told CNN.
"The point is any understudied, underappreciated group has fascinating lives, even a yucky spider, and we can learn something from it," he told CNN.
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