Study shows how mobility policies can help improve air quality

The “Shared Streets” research project, carried out by researchers at the Center for Innovation in Urban Public Policy (FGV Cities) at the Sao Paulo School of Business Administration (FGV EAESP), has obtained evidence of how urban public policies are central to reducing air pollution. This problem was the subject of a warning issued last week by the Sao Paulo State Environmental Agency (Cetesb), which identified a drop in air quality in the city of Sao Paulo in February 2024.

According to a report by Cetesb, the air was classified as poor quality in seven of the 15 stations installed in different districts across the city. In another 11 neighborhoods, pollution was considered moderate. In one neighborhood, Pinheiros, the air was rated as very poor quality. The main reason for the drop in air quality was the concentration of pollutants formed by burning fuels.

The distribution of space allocated to each mode of transportation illustrates the origin of the problem of high pollution rates in the city, which lies in the prioritization of private cars and motorcycles. 

According to FGV Cities’ research project, 60.8% of the surface area of Sao Paulo’s streets is given over to cars, which is more than nine times the amount used by mass transit (6.5%), 20 times the space dedicated exclusively to buses (2.9%) and three times the area used for sidewalks with an adequate width for pedestrians to use (17.1%).

When analyzing the environmental impacts of this prioritization, it was found that cars and motorbikes together are responsible for 75.4% of emissions, almost triple the daily emissions of local and long-distance buses (24.6%).

“We know that private vehicles account for 30% of total journeys, but they contribute more than 75% of greenhouse gas emissions. That in itself is a huge distortion regarding the negative externalities of each of these modes. So, I think this shows something and could lead to very pertinent discussions on ideas such as charging urban tolls for cars,” says FGV Cities researcher Frederico Roman Ramos, who was part of the project team. 

The social impacts of prioritizing private motor vehicles were measured and analyzed, including aspects such as air pollution, congestion time, traffic accidents and the health impacts of excess emissions of fine particulate matter.

“Shifting 1% of passengers from private vehicles to buses would generate a 1.38% net reduction in emissions. Given the current price of carbon credits (75 euros) and the total volume of daily emissions in the municipality of Sao Paulo (10,000 tons of CO2e), moving 1% of users from private vehicles to buses would generate savings of approximately 10,300 euros per day,” says Ramos.

The project compared the negative externalities generated by different modes of transportation. Using 2017 data from the Sao Paulo Atmospheric Emissions Inventory, produced by the Energy and Environment Institute (a Sao Paulo-based nonprofit organization), emissions of greenhouse gases and contaminants were estimated.

As well as measuring the extent of economic and social externalities, the researchers carried out a case study on Sao Paulo’s east side to assess the potential demand for non-motorized transportation and the impacts of investing in it.

 Health and the costs of poor air quality

Figures from the 2023 World Air Quality Report show that only seven of the 134 evaluated countries meet the standards set by the World Health Organization. In the city of Sao Paulo, air pollution has remained above the WHO’s recommended levels for the last 20 years, according to a 2022 report by the Sao Paulo-based Energy and Environment Institute.

This poor air quality has a direct impact on people’s health, according to data from the Shared Streets research project, which also investigated the costs of air pollution, assessing the impacts of annual exposure to inhalable particulate matter and the main health outcomes. Composed of very fine particles of solids or liquids suspended in the air, particulate matter is highly damaging to health when it enters the respiratory system.

According to the research, in 2019, this exposure was responsible for the deaths of 181 children, 144 cases of low birth weight, 1,040 premature births and 2,701 deaths in all age groups. The researchers identified that hospitalizations caused by poor air quality cost the public purse R$1.4 million.

“There are basically two sources of data: the Cetesb database, which tells us how much particulate matter was detected over the period; and the public health system’s information technology department, DataSUS, which shows a whole series of illnesses that are associated with this exposure to particulate matter,” Ramos explains.

Six specific causes of death (chronic obstructive pulmonary disease, diabetes, lower respiratory tract infection, lung cancer, ischemic heart disease and stroke) and adverse outcomes in children (prevalence of infant mortality, low-birth-weight babies and premature babies) were considered. Using a concentration-response equation, the proportion of cases related to exposure to particulate matter was estimated.

Sustainable policies

Last month, the Brazilian Senate approved the National Air Quality Policy, which aims to set emissions limits and monitor air quality throughout the country. As well as monitoring and controlling emissions, we require strategies to promote sustainable mobility that result in a fair distribution of shared public space and a consequent reduction in pollution.

Using simulations, the FGV Cities researchers investigated how switching to non-motorized modes of transportation would improve the environment. In scenarios in which walking is prioritized, the reduction in CO2 emissions would be 339 tons per day in the city of Sao Paulo. By providing better infrastructure for bicycles, CO2 emissions would also fall significantly, by between 139 and 237 tons per day. 

According to the executive summary of a report produced by the Shared Streets research project, among other things, the municipal government of Sao Paulo needs to encourage non-motorized forms of transportation, such as by expanding and improving sidewalks, which are “basic infrastructure for transforming public space while tackling the urgent challenge of the climate crisis and providing adequate conditions for public health in the city.”

“The existing municipal system that restricts the circulation of cars based on the last digit of their license plate could be gradually transformed into a congestion charge, similar to the charge levied on taxi and ridesharing services, and the proceeds of both charges could be used to subsidize policies to encourage walking. This combination of charging for car use and financing more sustainable alternatives is the next step for Sao Paulo on the road to promoting active mobility,” the researchers argue.

To find out more about the project, click here.