Everyone has the right to breathe clean air. This is the premise of the United Nations International Day of Clean Air for Blue Skies, celebrated annually on the 7th of September.

The majority of the global population is exposed daily to hazardous substances and waste that increase the chances of developing diseases and disabilities throughout life. A study by the World Health Organization (WHO) points out that, in middle or low-income countries, 97 percent of cities do not meet the air quality standards. The WHO also attributes around seven million annual premature deaths to air pollution. In addition, poor air quality damages the climate, food production, biodiversity and ecosystems.

Despite these facts, most citizens do not have access to real-time air quality data. “Monitoring is the first step in environmental management” points out David Tsai, chemical engineer and coordinator of the Emissions area at the Institute of Energy and Environment (IEMA). “A clear diagnosis of the problem is needed to find out whether there is pollution or not, at what level it is and what are the critical pollutants. As in medicine, only after a precise diagnosis is it possible to prescribe solutions.”

Along with ICLEI South America and other entities, IEMA is part of the technical coordination of the SEEG Brazil platform, an initiative of the Climate Observatory (OC) that produces annual estimates of greenhouse gas emissions in Brazil.

In an interview about how air quality has been affected throughout the Covid-19 pandemic David Tsai makes the case that economic recovery must be decoupled from a return to business as usual, especially from the return to previous levels of car traffic, and reflects on the importance of air quality measurements at the local level. Here’s what he had to say:

Is it possible to draw a parallel between the isolation caused by the COVID-19 pandemic and the improvement in air quality?

Tsai: Yes. Especially between March and May 2020. At the end of March, the Companhia Ambiental do Estado de São Paulo (CETESB) – the Environment Agency of São Paulo – published a note saying that air quality showed significant improvements in the first days of social isolation. Researcher Maria de Fátima Andrade, professor at the Institute of Astronomy, Geophysics and Atmospheric Sciences at the University of São Paulo (IAG-USP), also saw a significant reduction in pollutants directly linked to vehicular emissions, including a 30 percent reduction of inhalable particles.

IEMA analyzed CETESB data in São Paulo and found a clear reduction in fine inhalable particles (PM2.5) in the second half of March, when social distancing was beginning to be practiced. On the other hand, the isolation generated by the Covid-19 pandemic had little impact on ozone – this pollutant remained high.

According to data from the Climate Observatory, the pandemic has also not impacted deforestation, in the northern region of Brazil emissions of particulate matter remained high. In this region, however, surface air quality monitoring is non-existent, which makes it more difficult to make a more accurate analysis.

What can we learn from these findings?

Tsai: Air pollution levels can drop quickly if appropriate decisions are made, such as discouraging car use, with investment in public and active transport in large cities. The economic recovery must be based on these types of policy decisions, which could generate jobs and improve air quality.

With the end of isolation and quarantine, do you expect air quality improvement to continue? If not, what types of actions are possible to maintain the higher air quality we are currently seeing?

Tsai: Our prediction is that the improvement we have seen will fade quickly. Air pollutants, those that directly damage health, are chemical substances or inhalable particles characterized by a short life in the atmosphere. We are talking about hours and days. With the drop in emissions, atmospheric concentrations fall quickly. But the opposite is also true. With the end of isolation and quarantine and the resumption of emissions, atmospheric concentrations will return to previous, unhealthy levels. To improve air quality, it is necessary to reduce vehicular activity, putting into practice the best urban mobility guidelines, already established in Brazil from the National Urban Mobility Policy. In addition, solutions such as electric vehicles that have less impact on air quality should be incentivized.

In what ways does air quality directly and indirectly impact the well-being and quality of life of the population?

Tsai: Air quality is mainly a health issue. According to WHO, air pollution is now the second leading cause of mortality in the world, second only to Covid-19. This means that as the pandemic wanes, air pollution will again take the top spot. In addition, research indicates that pre-existing health conditions, such as respiratory and cardiovascular diseases and problems caused or aggravated by prolonged exposure to air pollution can increase the risk of severe cases of Covid-19.

According to IEMA data, most Brazilian states do not officially monitor air quality. Why is this monitoring important? In your view, what is the role of local governments in the process of monitoring air quality?

Tsai: Monitoring is the first step in environmental management. A clear diagnosis of the problem is needed to find out whether there is pollution or not, at what level it is and what the critical pollutants are. As in medicine, only after an accurate diagnosis is it possible to prescribe solutions that are effective and cost-effective.

According to Brazilian legislation, it is the responsibility of the federation units to monitor air quality. But generally, states do not have budgetary resources and technical personnel to implement monitoring.

To change this, local governments must demand and cooperate with state governments in order to create budgetary and technical conditions to enable monitoring. It is also possible for local governments themselves to take the lead, implementing their own monitoring. In this case, however, close coordination with the state body is necessary, so that there is no overlap of efforts and expenses, conflicts of information or incompatibility of information technologies that could hinder clear monitoring and communication with the population.