Air pollution data could be used to plan better transit routes

Researchers from the University of São Paulo are producing maps that show areas of the city of São Paulo with the highest concentration of air pollutants; the results of the studies were presented in the United States during FAPESP Week Illinois.

By Elton Alisson, from Chicago  |  Agência FAPESP – In addition to traffic information, in the not-too-distant future it will be possible to decide the best route and time to travel by car in cities like São Paulo – the capital of the state of the same name and Brazil’s largest metropolis – based on air quality data. Through studies supported by FAPESP, researchers from the Institute of Astronomy, Geophysics and Atmospheric Sciences (IAG) and the School of Public Health (FSP) of the University of São Paulo (USP) are producing maps that show the areas of the city with the highest pollution levels and the periods of peak emissions.

Some of the results of the projects were presented during a panel discussion on opportunities for studies on smart cities, held on April 9th at the opening of FAPESP Week Illinois, in Chicago (United States).

Organized by FAPESP in partnership with the University of Illinois System (UIS) – composed of the universities of Illinois in Chicago, Urbana-Champaign and Springfield – at the headquarters of the Discovery Partners Institute in Chicago, the meeting aims to create opportunities for scientific and technological cooperation between researchers from the state of São Paulo and the Midwest of the United States.

The event brings together researchers from universities and research institutions in the state of São Paulo, from the UIS, from the Great Lakes region of North America – located on the border between the United States and Canada – and from partner institutions in Canada and Mexico.

Participants’ areas of expertise include health and medicine, smart agriculture, climate, bioenergy, investing in democratic institutions, and smart cities.

“Smart cities use innovative information technologies to collect data that are used to build and operate interconnected urban systems to improve efficiency and enhance sustainability and resilience,” said Teresa Córdova, director of the Great Cities Institute of the University of Illinois in Chicago.

According to the researcher, some key technologies that are driving the development of solutions to make cities in different parts of the world smarter are fiber optics, radio signal sensors, and cell phone frequencies.

In São Paulo, for example, researchers from IAG and FSP-USP are using portable equipment such as laser particle counters and GPS devices installed in cars to measure and obtain geo-referenced data on the concentration of particulate matter to which drivers and passengers are exposed in the city on different routes and at different times of day.

"Based on the data collected during these studies, we were able to make maps and identify which regions of the city have the highest concentration of pollutants," Thiago Nogueira, professor at FSP-USP, told Agência FAPESP.

The researchers conducted a study assessing exposure to air pollutants during commutes by different modes of transportation in São Paulo – including car, bus, subway and bicycle – and in different regions of the city. The results showed that residents in the western region of the capital are exposed to higher concentrations of an air pollutant called black carbon. The regions with the best air quality were those with the highest concentration of green spaces. On the other hand, the regions with intermediate air quality had more high-rise buildings.

“We’ve seen that high-rise buildings have a negative effect on the dispersion of air pollution,” said Nogueira.

As part of an international project, the researchers also measured the levels of exposure to particulate matter in ten cities around the world, including São Paulo. The results of the study showed that off-peak exposure was 40% lower in the morning and 91% lower at night. The highest levels of exposure to high-concentrated particulate matter were recorded in situations where the car windows were open.

Another finding of the study was that bus drivers and passengers in São Paulo are exposed to higher levels of air pollutants than car and subway users. However, the levels of atmospheric exposure in São Paulo’s transport system were lower than those recorded in the other nine participating cities, located in Africa, Asia and South America.

“Despite the culture that São Paulo is a very polluted city, in comparison with other countries we observed that the levels of exposure to particulate matter in the capital are lower,” said Nogueira.

Some of the reasons for this difference are that the fuels used to power vehicles in Brazil are cleaner than those used in the countries of the other nine participating cities. In addition, Brazil’s energy matrix has a larger share of renewable sources, Nogueira explained.

“In Brazil, we also have Proconve [Health Program for the Control of Air Pollution from Motor Vehicles], which at every stage has established the requirement to use cleaner fuels and more efficient engines in the country,” Nogueira said.

Unequal access

Currently, 70% of the world’s greenhouse gas (GHG) emissions come from cities, almost half of which come from urban transportation, mostly from private cars, said Mariana Giannotti, professor at the Polytechnic School of USP (POLI-USP) and technology transfer coordinator at the Center for Metropolitan Studies (CEM) – a FAPESP Research, Innovation and Dissemination Center (RIDC). “In this sense, public transport represents an excellent strategy to address issues related to sustainability,” said the researcher during a lecture at the event.

Through a study conducted within the framework of the CEM, the researcher and collaborators compared access to public transport in São Paulo, New York, and London, based on users’ travel time and ticket costs. The results show that New York has a public transport integration policy that is fair and helps to reduce inequality in access to public transport. The situation in São Paulo is different, according to Giannotti.

“In São Paulo, inequality is being exacerbated by the way public transport users are charged. Normally, people in the city spend on average between 20% and 40% of their income on it, while New Yorkers spend between 5% and 10%,” she compared.

The biggest users of buses in São Paulo are people from lower economic classes, especially blacks, the researcher said.

“Rich people, who live in the best places in São Paulo, have access to better quality public transportation and are paying less,” she compared.