ISRO launches record 20 satellites in one go

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.

Jammu & Kashmir, Feb 7: Former Jammu and Kashmir chief ministers Mehbooba Mufti and Omar Abdullah, besides two political stalwarts from NC and its arch-rival PDP were booked under the stringent Public Safety Act (PSA) by the administration on Thursday, officials said.

A magistrate accompanied by police served the order to Mufti at the bungalow where she has been detained, the officials said.

Abdullah was also booked under the PSA, they said.

National Conference general secretary and former minister Ali Mohammed Sagar, who wields a support base in downtown city, was served with a PSA notice public order by the authorities.

Similarly, senior PDP leader Sartaj Madani was booked under the PSA. Madani is the maternal uncle of former chief minister Mehbooba Mufti.

Both Sagar and Madani were detained in the aftermath of August 5 crackdown by the Centre on politicians following abrogation of special status of the erstwhile state, besides its bifurcation into two union territories.

Their six-month preventive custody was ending on Thursday.

Earlier, the officials had said that former NC legislator Bashir Ahmed Veeri was also booked under the PSA but later it turned out that he had been released.

New Delhi, Apr 24: The trajectory of COVID-19 cases could have plateaued and might even fall for some weeks after the lockdown is lifted but India is likely to see a second wave in late July or August with a surge in the number of cases during the monsoon, say scientists.

The timing of the peak will depend on how India is able to control physical distancing and on the level of infection spreads after restrictions are relaxed, they said.

It looks apparent that the trajectory of daily new cases has reached a plateau and eventually it will take a downward fall, maybe for some weeks or even months, Samit Bhattacharya, associate professor at the Department of Mathematics, Shiv Nadar University, said.

Still, we may get a surge of new cases of the same coronavirus and this will be considered a second wave, Bhattacharya explained.

The second epidemic may come back in late July or August in the monsoon, although the peak timing will depend on how we control social distancing during that time, he said.

Rajesh Sundaresan, professor at Bengaluru's Indian Institute of Science (IISc), agreed.

“Once we return to normal activity levels, there is a chance that infection may begin to rise again. China is seeing this to some extent post easing of some restrictions on travel,” Sundaresan, corresponding author of a working paper by researchers at IISc and the Tata Institute of Fundamental Research (TIFR) in Mumbai, said.

On March 25, when the number of coronavirus cases was 618 with 13 deaths, the government announced a nationwide lockdown that was later extended to May 3.

On Friday, the death toll due to COVID-19 rose to 718 and the number of cases to 23,077, according to the Union Health Ministry.

In good news, officials said this week that the doubling rate of cases has slowed down in the period, going from 3.4 days before lockdown to 7.5 days, with 18 states doing better than the national average. The recovery rate has also almost doubled in the last 10 days.

"Looking at the new cases in the past few days, it seems the growth of new daily infection is much slower than earlier. This apparently indicates that we might have reached at the plateau of the growth curve, Bhattacharya said.

He noted that recent studies in China and Europe observed that the infection might relapse in those people who have already recovered from earlier phases.

So, there is no evidence that the earlier infection may help acquire immunity against the second infection. And in that way, the entire population may be vulnerable to the second wave to some extent, said the scientist.

In their study unveiled this week, IISc and TIFR researchers analysed the impact of strategies such as case isolation, home quarantine, social distancing and various post-lockdown restrictions on COVID-19 that might remain in force for some time.

The study modelled on Bengaluru and Mumbai suggests the infection is likely to have a second wave and the public health threat will remain, unless steps are taken to aggressively trace, localise, isolate the cases, and prevent influx of new infections.

The new levels and the peaking times for healthcare demand depend on the levels of infection spreads in each city at the time of relaxation of restrictions, they said.

The lockdown is currently upon us. It has given us valuable time. Let us test, trace, quarantine, isolate, practice better hygiene, search for a vaccine, etc. We should do these anyway, and these are being done. When and how to lift the lockdown is going to be a difficult decision to make, said Sundaresan.

It's clear that it's going to be phased. What our team is focusing on is to come up with tools to help the decision makers assess the public health impact of various choices, he said.

According to the experts, infectious diseases spread via contact between infectious and susceptible people. In the absence of any control measures, an outbreak will grow as long as the average number of people infected by each infectious person is more than one.

Once enough people are immune there will be fewer people susceptible to the infection and the outbreak will die.

However, when an outbreak is brought under control by social distancing and other interventions, it is possible only a small proportion of the population will have been infected and gained immunity, they said.

This means enough susceptible people may remain to fuel a second wave if controls are relaxed and infection is reintroduced.

Until the vaccine comes on the market, we have to remain alert Once sporadic cases occur here and there in the country, we immediately need to implement quarantine or social distancing locally for the people in that region, and also need to perform tests to identify positive cases irrespective of showing symptoms, Bhattacharya explained.

Note that these monsoon months are also flu season in many places of India. So, we should not ignore the early signs of the flu symptoms. Irrespective of symptoms, we need to increase tests in the hotspots to identify people and contain the surge, he said.

Sundaresan added that the timeline for a second wave will depend on a lot of circumstances which may change as the time passes.

Significant testing may have been underway, there may be behavioural changes with people becoming more careful about their hygiene, wearing masks may become more common, etc. All these responses may help restrict the second wave, he said.

A study published in The Lancet journal earlier this month modelled the potential adverse consequences of premature relaxation of interventions, and found it might lead to a second wave of infections.

The finding is critical to governments globally, because it warns against premature relaxation of strict interventions, the researchers said.

While interventions to control the spread of SARS-CoV-2 are in place, countries will need to work toward returning to normalcy; thus, knowledge of the effect of each intervention is urgently required, they said in the study.

According to a recent analysis by the Harvard Chan School of Public Health, the best strategy to ease the critical care burden and loss of life from COVID-19 might be on-again, off-again social distancing.

In the absence of such interventions, surveillance and intermittent distancing may need to be maintained into 2022, which would present a substantial social and economic burden, the researchers wrote.p