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An eye on ozone

Atmospheric pollution is an old friend of the inhabitants of greater São Paulo. What not everyone knows is that today, of the various atmospheric pollutants, ozone is the one that most worries the specialists in the area and is one of those that most often exceeds the safety limits for air quality. Its high concentration in the lower atmosphere, besides opening a doorway to respiratory infections, unchains oxidation processes that cause precocious aging, damages agriculture and provokes the corrosion of materials.

To develop technology to forecast beforehand the formation of ozone in the lower atmosphere, and to implement preventative actions of health protection, is the objective of the research that is being carried out by the Chemical Engineering Department of Poli/USP, in partnership with the State Company of Technology and Environmental Sanitation (Cetesb) and has the support of FAPESP. A multidisciplinary team of 18 people, under the coordination of Roberto Guardani, has been at work since last year.

The formation of ozone depends to a large extent on the temperature and radiation and suffers the direct influence of the sun, of the air humidity and wind action. That is why, Ibirapuera Park is one of the regions with the highest concentration of ozone in the city of São Paulo, says Cláudio Oller do Nascimento, a professor of chemical engineering of Poli/USP and a member of the team. The park has emission areas of other pollutants all the way around it, the wind carries them and the park has high luminosity, especially in sunny clear winter days.

The technology that is being developed depends on neural networks to analyze the meteorological data, on the concentration of atmospheric pollutants forerunners to ozone and of indicators obtained hourly by the Cetesb stations that monitor the quality of air and are scattered throughout the city. In the opinion of Carlos Ibsen Vianna Lacava, a meteorologist with Cetesb involved in the project, all of the data collected by the measuring stations since 1981 are stored in a computerized system – they are the raw material for the study. Already during its first phase, in the year 2000, it was possible to equip Cetesb with tools for the forecasting of ozone for the afternoon of the same day (and it will shortly be able to count upon a mobile measuring station).

In 2002, when the project is completed, and having had the technical workforce adequately trained, Cetesb will be able to inform in its daily bulletin – Lacava explains -, both the atmospheric conditions and the quality of the air plus a forecast for the formation of ozone with a 24-hour notice. In this way it will be creating conditions for preventative actions, such as, suspending sporting events, physical activities in schools, parks and clubs; to encourage the use of collective transport; to restrict the circulation of vehicles in certain areas. And more: it will be possible to develop policies for industrial control and for vehicle emission and to implement inspection programs and car maintenance – important steps for more efficient urban planning.