India's missile defence shield ready: Defence Research and Development Organisation

Washington, Apr 23: Air pollution over northern India has plummeted to a 20-year-low for this time of the year, according to satellite data published by US space agency National Aeronautics and Space Administration (NASA).
The US space agency's satellite sensors observed aerosol levels at a 20-year low post the countrywide lockdown, implemented to slow the spread of the novel coronavirus.

"We knew we would see changes in atmospheric composition in many places during the lockdown," said Pawan Gupta, a Universities Space Research Association (USRA) scientist at NASA''s Marshall Space Flight Center. "But I have never seen aerosol values so low in the Indo-Gangetic Plain at this time of year," added Mr Gupta.

Acting Assistant Secretary of State for South and Central Asia Alice G Wells tweeted, "These images from NASA were taken each spring starting in 2016 and show a 20-year low in airborne particle levels over India. When India and the world are ready to work and travel again, let's not forget that collaborative action can result in cleaner air."

The data published with maps show aerosol optical depth (AOD) in 2020 compared to the average for 2016-2019. Aerosol optical depth is a measure of how light is absorbed or reflected by airborne particles as it travels through the atmosphere.

If aerosols are concentrated near the surface, an optical depth of 1 or above indicates very hazy conditions. An optical depth, or thickness, of less than 0.1 over the entire atmospheric vertical column is considered "clean." The data were retrieved by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite.

In the first few days of the lockdown, it was difficult to observe a change in the pollution signature. "We saw an aerosol decrease in the first week of the shutdown, but that was due to a combination of rain and the lockdown," said Mr Gupta.

Around March 27, heavy rain poured over vast areas of northern India and helped clear the air of aerosols. Aerosol concentrations usually increase again after such heavy precipitation.

"After the rainfall, I was really impressed that aerosol levels did not go up and return to normal. We saw a gradual decrease and things have been staying at the level we might expect without anthropogenic emissions," Mr Gupta said.

On March 25, the Indian government placed its 1.3 billion citizens under a strict lockdown to reduce the spread of COVID-19. The countrywide mandate decreased activity at factories and severely reduced car, bus, truck and airplane traffic. Every year, aerosols from anthropogenic (human-made) sources contribute to unhealthy levels of air pollution in many Indian cities.

Aerosols are tiny solid and liquid particles suspended in the air that reduce visibility and can damage the human lungs and heart.

In southern India though, the story is a little hazier. Satellite data show aerosol levels have not yet decreased to the same extent. In fact, levels seem to be slightly higher than in the past four years. The reasons are unclear but could be related to recent weather patterns, agricultural fires, winds or other factors.

"This a model scientific experiment," Robert Levy, program leader for NASA's MODIS aerosol products, said about the lockdown and its effects on pollution.

"We have a unique opportunity to learn how the atmosphere reacts to sharp and sudden reductions in emissions from certain sectors. This can help us separate how natural and human sources of aerosols affect the atmosphere," Mr Levy added.

May 18: The Central Board of Secondary Education (CBSE) on Monday announced the date sheet for the pending class 10 and 12 board exams, which will now be held from July 1 to 15.

The exams were postponed due to the nationwide lockdown imposed on March 25 to contain the spread of COVID-19.

The Class 10 board exams are pending only in the North East Delhi.

"The Class 10 exams will be staggered on four dates, starting July 1. The first paper will be Social Science, while the next day students will be required to appear for the Science exam,” said Sanyam Bhardwaj, the Controller of Examination, CBSE.

“On July 10, exams will be conducted for both courses of Hindi and on July 15 for both courses of English," he said.

On health guidelines for students, Bhardwaj said that they will be required to carry their own sanitiser bottles and wear masks to examination centres.

"Parents will have to ensure that their ward is not sick and candidates will have to strictly follow physical-distancing norms," he said.

For Class 12, the Home Science exam will be held on July 1, followed by both courses of Hindi the next day.

The Class 12 Business Studies exam has been scheduled for July 9, followed by Biotechnology on July 10 and Geography on July 11.

Kochi, Apr 4: France on Saturday evacuated 112

French citizens stranded in Kerala and Tamil Nadu in a special Air India flight, official sources said here.

The Embassy of France had made a request to the Kerala government to facilitate the journey of the French citizens stranded due to the lockdown announced by the central government to prevent the spread of novel coronavirus.

The French citizens, mostly tourists and those who came for Ayurvedic treatment, were brought here by the state tourism department 24 days ahead of their trip.

They underwent a medical examination before boarding the flight for Paris from Cochin International Airport at 08.13 am on Saturday, officials said.

The Air India flight was chartered by the French government for evacuating its citizens in various cities in India including Kochi, Bengaluru and Mumbai.

On Friday, Gulf nation Oman had evacuated its 46 citizens stranded in Kochi in an Oman Air flight.