São Paulo has a heavy air and it’s not new. An analysis by Iema (Institute of Energy and Environment) shows how the city presents, in all the evaluated indices, pollution rates higher than those recommended by the WHO (World Health Organization).
The Iema report, released this Thursday (26), uses data made available by Cetesb (Environmental Company of the State of São Paulo), collected at 29 points in the city. The survey covers the period from 2000 to 2021.
Levels of three critical pollutants for São Paulo were evaluated: particulate matter, ozone (O3) and nitrogen dioxide (NOtwo).
“We just rechecked the fact that São Paulo is polluted”, says David Tsai, project manager at Iema.
Although the city still has levels considerably higher than the ideal scenario for health indicated by the WHO, there is, to some degree, good news to be told. At least for particulate matter and NOtwothe concentrations of pollutants have been decreasing.
The big problem is that they decrease from previously very high levels.
Starting with particulate matter, for example. The name is almost literal: it is a mixture of solid and liquid compounds (dispersed in smoke and dust) that are suspended in the air and end up in your nose and lungs. If you’re imagining buses, cars, and factory chimneys puffing smoke, you’re imagining it right.
When breathing in particulate matter, depending on the size of the particle — the smaller the worse — it can end up in your lungs and even your bloodstream, which, as you can imagine, can lead to a variety of health problems.
According to Iema’s analysis, in the early 2000s, the city of São Paulo had particulate matter (PM) rates that were 3 to 5 times higher than the WHO standard currently indicates (which was updated at the end of last year).
Today, for the MP10 (the number indicates the size of the measured compound: 10 micrometers), the values for the capital of São Paulo are “only” twice as high as ideal. In the case of MP2.5 (which, due to its size, is more harmful), the concentration is 3 to 4 times higher than indicated.
The reductions observed in this area must be related to greater control of vehicular emissions, which is associated with technological improvements in vehicles and with the Proconve (Program for Control of Air Pollution by Motor Vehicles).
NO valuestwo 2020 and 2021, in turn, came within the standards established by the WHO. That’s if we took old patterns into account. The international organization’s 2021 update, however, made the ideal levels more restrictive, reducing it by four times. As a result, no monitoring station in São Paulo has achieved adequate standards, despite reductions in the last two decades.
Nitrogen oxides are produced in combustion processes — again, vehicles enter this equation.
“Great, the particulate matter is reducing, NOtwo is shrinking, so we’re doing some things right. But we need to do more because we are still at double, triple, quadruple the WHO recommendation,” says Tsai.
And finally, ozone, which is a secondary pollutant, produced by reactions between other compounds, such as nitrogen oxides and volatile organic compounds (you know the smell of gasoline at gas stations? That’s a volatile compound).
The case of ozone is the most worrisome, says Tsai. “It fluctuated at very high levels, but did not show a downward trend”, says the Iema researcher. “We are stagnant.”
There is still no clear explanation of what is involved in this maintenance of the numbers related to O3but Tsai says that the institute is in contact with Cetesb to understand and think of solutions.
Another point that drew attention, according to Tsai, was the maintenance of pollution levels as high as before, even in 2020 and 2021, still at the beginning of the Covid pandemic, at which time a large part of displacements through the city had reductions. Even some measures of pollution in the first months of Covid in Brazil showed a reduction in pollution in cities like São Paulo.
local pollution
You might be thinking: but it all depends on where the pollution is measured. In quieter neighborhoods, without so much traffic, pollution levels should be lower.
To some extent, you are right. But, if you are anywhere in São Paulo, you will necessarily be in contact with breathable air above the values considered safe by the WHO.
Tsai brings bad news. “Even in the best scenarios, we exceed the WHO recommendations.”
In any case, there is a difference between the pollution measurement sites and their representativeness for the city. For example, the air recorded at the peak of Jaraguá can be seen as a good gauge for the “average air” of those who breathe in São Paulo — it is an urban-scale monitoring station, that is, representative for the entire city. . Meanwhile, the Tietê waterfront station is not a good parameter for broader analyses, considering the intense and constant flow of cars — it is, therefore, a station with very local representation, on a micro scale.
But, as mentioned earlier, even stations on an urban scale, such as the distant peak of Jaraguá, do not escape pollution and are far from acceptable WHO standards.
Monitoring example city
São Paulo is polluted and this is clear in the survey and for some time. But it is only possible to know and quantify this thanks to the monitoring system that the city has.
According to Tsai, the capital has a robust monitoring system. “This is an exceptional scenario in Brazil. Few states have a network like São Paulo. The vast majority do not even have an air quality monitoring station”, says the researcher. “It is necessary to recognize that. Twenty years of data is not a small thing. Public data from the environmental agency of São Paulo.”
The researcher points out that even many capitals do not have monitoring stations. The entire northern region of the country —very affected by fires, which generate large amounts of particulate matter— does not have any stations.
“In most cases, we don’t know what the Brazilian is breathing”, says Tsai.
