Lockdown's Impact: Pollution Declines, Nature's Revival

The coronavirus lockdown has had a significant impact on pollution levels globally. With human activity restricted, air pollution has decreased in many parts of the world. In India, for example, the lockdown led to a 71% drop in pollution levels in New Delhi, the capital city. Similarly, in China, satellite data revealed a 48% drop in nitrogen dioxide densities over the country during the early stages of the pandemic. The reduction in economic activity and travel resulted in improved air quality and clearer skies in many regions. However, the impact on light pollution was less pronounced, as it is primarily influenced by permanent lighting rather than vehicle headlights or private lighting. The lockdown also positively affected water pollution, with improvements observed in the Ganga and Yamuna rivers in India. Overall, the coronavirus lockdown provided a temporary respite from pollution, but long-term structural changes are needed for a lasting impact on the environment.

Air pollution

The coronavirus lockdown has had a significant impact on air pollution levels worldwide. NASA's satellite images show a dramatic decline in pollution levels in China, specifically in Wuhan, Beijing, and Shanghai, due to decreased economic activity. Similarly, Reuters visualisations based on data from NASA's Global Modeling and Data Assimilation team indicate a decrease in pollutant concentrations in China's Hubei province after travel restrictions were imposed.

The lockdown measures have resulted in the shutdown of factories and roads, leading to reduced emissions and an increase in air quality globally. This trend is supported by research from Columbia University, which found that carbon monoxide and carbon dioxide emissions decreased by around 50% and 10%, respectively, in New York City. Additionally, an analysis by Carbon Brief noted a 25% decrease in emissions across China during February 2020 compared to the same period in 2019.

The improvements in air quality have been particularly notable in highly polluted cities like Beijing, Bengaluru, Delhi, Lima, Mumbai, Rome, and Wuhan. These cities witnessed a significant decline in the concentration of key air pollutants, including particulate matter (PM2.5 and PM10), nitrogen dioxide (NO2), and sulphur dioxide (SO2). The reduction in these pollutants is mainly attributed to the halt in anthropogenic activities, such as transportation and industrial operations, which are the primary sources of such pollutants.

However, the impact of the lockdown on air pollution levels has varied across different regions. For instance, cities like Las Vegas, London, Madrid, and Moscow showed mixed trends, with some pollutants decreasing while others remained unchanged or increased. Additionally, the improvements in air quality due to the lockdown are temporary, as pollution levels tend to increase again once the restrictions are lifted.

Overall, the coronavirus lockdown has had a positive impact on air quality, especially in highly polluted regions. The reduction in air pollution during the lockdown highlights the significant contribution of anthropogenic activities to air pollution and provides an opportunity for policymakers and governments to implement long-term strategies to improve air quality and protect public health.

Light pollution

In the city of Granada, Spain, a study was conducted to measure light pollution levels before and during the lockdown from mid-March to the end of May 2020. The results revealed a 20% decrease in the overall light output of the city during the lockdown. This reduction was even more pronounced in the blue end of the light spectrum, with a 45% decrease in sky brightness. This was attributed to the reduction in vehicle headlights, private lighting, and ornamental illumination of city monuments.

The lockdown also provided an opportunity for astronomers and amateur stargazers to observe the night sky with potentially reduced light pollution. In Dorset, England, residents were encouraged to participate in an annual Star Count to discover the impact of the lockdown on light pollution. By counting the number of stars visible in the Orion constellation, citizen scientists helped map the best and worst places in England to enjoy a star-filled night sky.

While the COVID-19 lockdown provided a temporary respite from light pollution in some areas, it also highlighted the need for long-term solutions. Light pollution has been recognized as a significant issue, with about 83% of people worldwide living under light-polluted skies. It has been linked to various adverse health effects, including sleep deprivation, increased headaches, worker fatigue, stress, decreased sexual function, and increased anxiety. Additionally, it disrupts ecosystems, interferes with astronomical observations, and compromises the aesthetic beauty of the night sky.

To address light pollution, simple steps such as adjusting light fixtures, using appropriate light bulbs, and educating the public to push for legislative change can be implemented. By reducing light pollution, we can not only improve human health and protect the environment but also reclaim our connection to the starry night sky that has inspired wonder and awe throughout history.

Water pollution

The lockdown has had a direct influence on water dynamics and pollution. The reduction in human-based activities generated by the lockdown enabled improvements in water quality in urban rivers.

A study on the Capibaribe and Tejipió rivers in Brazil found that the turbidity values in the water bodies varied from 6 mg. L−1 up to 40 mg. L−1. Overall, the reduction in human-based activities generated by the lockdown enabled improvements in water quality in these urban rivers.

In India, the lockdown improved the water quality of the Ganga and Yamuna rivers. The bacterial population of coliform and faecal coliform decreased during the pandemic. Several real-time monitoring stations were constructed on the banks of the Ganga River, and 27 out of 36 stations reported water quality under the permissible limit during the lockdown period.

A study on Lake Hussain Sagar in India found that the lockdown had a significant effect on the pollution characteristics of the water bodies. The lockdown had a positive impact on the lake's water quality, with a notable reduction in the concentrations of chlorophyll-a, coloured dissolved organic matter, and total suspended solids.

In Mexico, the COVID-19 lockdown improved the water quality of the Santiago River, one of the country's most polluted rivers. The lockdown restrictions drastically reduced faecal coliform and total coliform concentrations by 31.18% and 14.24%, respectively. The lockdown also significantly reduced nitrate and sulfate levels in the Santiago River by 36.11% and 5.25%, compared to the pre-lockdown period.

Noise pollution

The COVID-19 lockdown has led to a significant reduction in noise pollution. The decrease in traffic and limited factory hours have contributed to this positive change. In Karachi, Pakistan, for instance, the lockdown resulted in a 40% decrease in noise levels, with residents of the city reporting improved health and reduced breathing difficulties.

In Madrid, Spain, the lockdown led to a noise reduction of between 4 and 6 decibels, with the changes being more pronounced during the weekends. The absence of vehicles and people on the streets resulted in a quieter city, with similar observations in other cities like New York, Barcelona, Paris, and Lyon.

The reduction in human-caused vibrations during the lockdown was not limited to densely populated areas. Even remote areas like Germany's Black Forest and Rundu in Namibia experienced a decrease in seismic noise. This period of reduced human activity allowed scientists to study and differentiate between human-caused and natural seismic noise more effectively.

The COVID-19 lockdown, therefore, provided a unique opportunity to study the impact of human activities on noise pollution and offered a glimpse of what the world could be like with reduced noise pollution.

Impact on wildlife

The COVID-19 lockdown has had a profound impact on wildlife, with reduced human activity leading to some surprising changes in animal behaviour. This period, coined the "anthropause" by researchers, has provided valuable insights into how animals respond when humans are out of the picture.

One of the most noticeable effects has been the return of certain species to metropolitan areas. Pumas have been spotted in downtown Santiago, Chile, and dolphins have appeared in the usually busy harbour of Trieste, Italy. In Japan, deer have been seen wandering through underpasses in Nara, and in the UK, foxes have become an even more common sight in cities. Birds, too, have been affected, with reports of increased birdsong in French cities during lockdown.

For some species, the lockdown has meant a struggle to find food. Gulls, rats, and monkeys in urban areas are usually dependent on human food sources like trash or picnic leftovers, and their usual sources of nutrition have disappeared. On the other hand, some species that rely less on human food or are less affected by human activity may benefit from the reduced human presence.

The lockdown has also had an impact on endangered species. With fewer people around, species like rhinos or raptors in remote areas may be at increased risk of poaching or persecution. This period of reduced human mobility provides an opportunity to study the extent to which human activity usually affects wildlife and to develop strategies for better human-wildlife coexistence.

While the lockdown has had some positive effects on wildlife, it's important to note that this is not the new normal. As soon as lockdown restrictions are lifted and human activity resumes, wildlife is likely to return to its previous patterns, and any benefits gained during the lockdown may be lost. Researchers also face a catch-22 situation, as the lockdown has disrupted animal behaviour, but they are unable to study it fully due to travel restrictions.

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