Evolution of Vehicle Emission Factors in a Megacity Affected by Extensive Biofuel Use: Results of Tunnel Measurements in São Paulo, Brazil

Abstract

Since 2001, four emission measurement campaigns have been conducted in multiple traffic tunnels in the megacity of Saõ Paulo, Brazil, an area with a fleet of more than 7 million vehicles running on fuels with high biofuel contents: gasoline + ethanol for lightduty vehicles (LDVs) and diesel + biodiesel for heavy-duty vehicles (HDVs). Emission factors for LDVs and HDVs were calculated using a carbon balance method, the pollutants considered including nitrogen oxides (NO x ), carbon monoxide (CO), and sulfur dioxide, as well as carbon dioxide and ethanol. From 2001 to 2018, fleet-average emission factors for LDVs and HDVs, respectively, were found to decrease by 4.9 and 5.1% per year for CO and by 5.5 and 4.2% per year for NO x . These reductions demonstrate that regulations for vehicle emissions adopted in Brazil in the last 30 years improved air quality in the megacity of Saõ Paulo significantly, albeit with a clear delay. These findings, especially those for CO, indicate that official emission inventories underestimate vehicle emissions. Here, we demonstrated that the adoption of emission factors calculated under real-world conditions can dramatically improve air quality modeling in the region.

Ubiquity of Anthropogenic Terpenoids in Cities Worldwide: Emission Ratios, Emission Quantification and Implications for Urban Atmospheric Chemistry

“…During the SOPRO project, VOC canister samples were collected in two tunnels in the São Paulo Metropolitan Area during two 1‐week duration field experiments as described in Nogueira et al. (2021) (Jânio Quadros Tunnel −46° 41' 36.28" W, −23° 35' 15.81 S" and Rodoanel Tunnel −46° 47' 43.85 W", −23° 27' 38.94 S"). Details on VOC sampling and analysis are provided in the Supplement Information (Text S1 in Supporting Information ).…”

Atmospheric effects of air pollution during dry and wet periods in São Paulo

“…45 Therefore, we updated the Brazilian emission factors in the VEIN model to represent tunnel measurements made in the year 2018 ‡‡ The tunnel measurements made in October of 2018 represent fleet-average values, and then, we calculated emission factors weighted by the 2018 respective circulating fleet, and the resulting ratio between the observed and calculated emission factor was the factor to multiply the CETESB emission factors to represent real-world measurements, as shown by Gavidia-Calderon et al 46 and evaluated by Nogueira et al 45 It is important to note that the four aspects make this inventory different from Ibarra-Espinosa et al 25 Here, we extrapolated morning rush hour GPS traffic data and updated the emission factors with tunnel measurements; we did not consider vehicle flow speed in emission factors, and we included resuspension emissions from paved road circulation according to the United States Environmental Protection Agency methods. 47 Furthermore, VEIN emissions were speciated according to the chemical mechanism RADM2/MADE/SORGAM 48 by speciating the organic volatile compounds (VOCs) and then grouping species following Carter's methodology, 49 previously included in VEIN §…”

Pollutant concentration prediction from traffic data analysis for concrete durability studies in Madrid Calle 30 urban tunnels

“…It can be noticed that the gas which presents the greatest concentration is the CO 2 , as its average concentration in the gallery is 789.04 ppm, being this concentration signi cantly higher than the atmospheric one, which is typically considered around 300-400 ppm (Sanjuán et al, 2020). This is because emissions measured inside urban tunnels are shown to have higher concentrations than the atmospheric ones (usually 3-5 times of that in atmospheric levels), and they are not in uenced by external sources (Ba et al, 2017;Nogueira et al, 2021). In lower concentrations, CO, SO 2 , NO and NOx were also detected.…”