India is home to 1.3 billion people. As schools, workplaces, industry and transport remain closed, pollutants found in the air have been able to settle.

According to air pollution data analysed by the Centre for Research on Energy and Clean Air, on day one of the coronavirus lockdown, the average particle matter (PM 2.5) in the air decreased by 22 percent. The average nitrogen dioxide - which comes from burning fossil fuels - dropped by 15 percent.

The reduced air pollution is rare for India, which at the end of 2019, was reported as home to six of the world's 10 most-polluted cities.

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According to a report by the Global Alliance of Health and Pollution, India has more than two million pollution-related deaths a year - the highest number in the world.

"These are the extraordinary times," said Anumita Roy Chowdhury, executive director of the Centre for Science and Environment in New Delhi.

He went on to say, "Because of the public health emergency, everything is shut down. Factories are shut. No construction happening. And because we are not travelling, there are no vehicles on the road. And naturally because of that, pollution levels have reduced dramatically."

The positive impact of the lockdown is not just limited to better air quality and higher visibility.

India's Central Pollution Control Board said the water in the Ganges, India's longest river, had become fit for bathing. This was deduced with the help of real-time monitors placed along the river.

The report cited a decrease in runoff from 28 industrial clusters, and a reduction in dumping of rubbish, as some of the biggest reasons for the improved water quality.

Recent analysis by the Delhi Pollution Control Board confirms the quality of the Yamuna River, which skirts the city of New Delhi, has also improved during the lockdown.

Environment activist and social worker Vimlendu Jha warned the improvements are "short-lived" and will probably fade as rampant economic activity resumes after the lockdown.

He went on to say the government and policymakers need to study the data collected during the lockdown, to identify sources of pollution and devise better standards to help improve the environment.

Lockdown measures remain in place across India until at least May 3.