​​​​​With a third of the planet's population in quarantine, coronavirus pandemic has changed not only the life style of the human beings. Since the beginning of the stiffening of social isolation measures recommended by WHO, when industries reduced their production and less vehicles were circulating in streets and highways, the environment has also experienced a big - and positive - impact.

CLEANER AIR

The major change was related to the reduction of air pollution. For example, in New York, one of the most affected cities by the pandemic, carbon-monoxide emissions declined 50% as compared to the same period last year, according to Columbia University. The same happened in the big Brazilian metropolises that adopted restrictive measures after European countries: according to the Environmental Company of the State of São Paulo (Cetesb), air pollution also fell by half after a week of quarantine in the São Paulo capital.

The traffic of cars, buses and trucks is the most relevant contributor to the emission of polluting gases in big cities like São Paulo. While cargo transportation and bus traffic continued, the main fall in pollution came from the lower use of cars.

According to the same survey, the rate of pollutants that cause respiratory diseases has also showed a 30% decrease in São Paulo.  A collection of maps made by Santa Catarina’s Environment Institute (IMA/SC) based on Sentinel-5P satellite images, of the European Space Agency (ESA), has revealed smaller nitrogen dioxide stains - one of the pollutants issued by the burning of fossil fuels - in cities such as Rio de Janeiro, Curitiba and Belo Horizonte.

IN ISOLATION, 69 COUNTRIES RECORD FALL IN EMISSIONS

A recent survey published in Nature Climate Change magazine shows that nitrogen dioxide emissions derived from fossil fuel sources have reached a maximum daily decline of 17% in April. This major decline occurred on April 7. In that day, China, the USA, India and all other main carbon issuer countries were in high level of social isolation. The study is very comprehensive, as it used data from 69 countries representing 97% of global emissions and 85% of the world's population. Researchers compared April this year versus April last year. In the daily average from the beginning of the year up to last month, there was a 8.6% reduction of this gas due to the pandemic.

CLEANER AND EMPTIER BEACHES

In addition to air pollutants, other aspects were seen throughout the world. For example, in Brazil, the water of the beaches in Rio de Janeiro - almost always crowded with bathers and polluted - became clear.

According to a G1 website report since many people stay at home, the volume of trash collected in Rio’s beaches was dramatically reduced. Currently, the fall during weekdays is 91%. According to Comlurb, the company responsible for the urban cleaning of Rio de Janeiro capital, it used to collect 120 tons of waste in the sands from Monday to Friday during summer and 341 tons in weekends - 146 on Saturdays and 195 on Sundays. Now, these figures were reduced to 10 tons on the entire coast on weekdays and 15 tons on weekends, according to the company’s data.

The same occurred with the water in Venice channels, always with extensive flow of gondolas and tourists from the whole world. Some residents of northern India were able to see part of the Dhauladhar range in the Himalayas for the first time. Due to the high level of air pollution in the country, this phenomenon was not seen since Second War II.

In addition to air pollutants, other aspects could be perceived worldwide. In Brazil, for example, the waters of Rio's beaches - almost always crowded with bathers and polluted - appeared crystal clear.

The less number of people in the streets also opened the space for the entry of animals into the urban environment. In Liandudno, in the United Kingdom, a herd of goats has taken over the city during the pandemic. The same happened with animals in Thailand, India and South Africa. What lessons should we take from this period?