Airborne particles in the Brazilian city of São Paulo: One-year investigation for the chemical composition and source apportionment

Abstract

<p><strong>Abstract.</strong> São Paulo in Brazil has relatively relaxed regulations for ambient air pollution standards and often experiences high air pollution levels due to emissions of airborne particles from local sources and long-range transport of biomass burning-impacted air masses. In order to evaluate the sources of particulate air pollution (PM) and related health risks, a year-round sampling was performed for PM<sub>2.5</sub> (≤ 2.5 μm) and PM<sub>10</sub> (≤ 10 μm) in 2014 through intensive (every day sampling in wintertime) and extensive campaigns (once a week for the whole year) with 24 h of sampling. This year was characterized to have lower average precipitation comparing to meteorological data, and high pollution episodes were observed all year round, with a significant increase of pollution level in the intensive campaign, which was performed during wintertime. Different chemical constituents, such as carbonaceous species, polycyclic aromatic hydrocarbons (PAHs) and derivatives, water-soluble ions and biomass burning tracers were identified in order to evaluate health risks and to apportion sources. The species such as PAHs, inorganic and organic ions and monosaccharides were determined by chromatographic techniques and carbonaceous species by thermal-optical analysis. The associated risks to particulate matter exposure based on PAH concentrations were also assessed, along with indexes such as the benzo[a]pyrene equivalent (BaPE) and lung cancer risk (LCR). High BaPE and LCR were observed in most of the samples, rising to critical values in the wintertime. Also, biomass burning tracers and PAHs were higher in this season, while secondarily formed ions presented low variation throughout the year. Meanwhile, vehicular tracer species were also higher in the intensive campaign suggesting the influence of lower dispersion conditions in that period. Source apportionment was done by Positive Matrix Factorization (PMF), which indicated five different factors: road dust, industrial emissions, vehicular exhaust, biomass burning and secondary processes. The results highlighted the contribution of vehicular emissions and the significant input from biomass combustion in wintertime, suggesting that most of the particulate matter is due to local sources, besides the influence of pre-harvest sugarcane burning.</p>

Influence of Air Pollution and Soil Contamination on the Contents of Polycyclic Aromatic Hydrocarbons (PAHs) in Vegetables Grown in Urban Gardens of Sao Paulo, Brazil

“…The PAH concentration found in the PM 2.5 (≤2.5 µm) sampled in an intensive campaign during the winter of 2014 (Martins Pereira et al, 2017) were 23.3 ng m −3 highlighting the contribution of vehicular emissions.…”

“…Pyrogenic PAHs in urban centres are mainly derived from incomplete combustion in motor vehicles and are distributed as gases and ultrafine particles (Marr et al, 2006;Chrysikou et al, 2009). In Sao Paulo, atmospheric pollutants result mainly from the vehicular fleet of 8 million vehicles (CETESB Sao Paulo State Environmental Agency, 2015a;Martins Pereira et al, 2017). Petrogenic PAH sources are common in cities, due to the transportation, storage, and use of crude oil and its products.…”

Source apportionment study on particulate air pollution in two high-altitude Bolivian cities: La Paz and El Alto

“…All these elements are typical byproducts of the combustion of plastic mixed with vegetation or wood (Cash et al, 2021;Christian et al, 2010;Guttikunda et al, 2013Guttikunda et al, , 2019Kumar et al, 2018;Lanz et al, 2008;Rivellini et al, 2017;Simoneit, 2002;Singh et al, 2008). Similar factors have been previously observed in prior studies (Martins Pereira et al, 2017;Rai et al, 2020;Zíková et al, 2016), but only very few of these studies were able to distinguish it as a separate factor from biomass burning or traffic, given the ubiquity of some of the tracers. This factor is responsible for only 5 and 2% (1.8±1.8 µg m -3 and 0.8±1.2 µg m -3 ) on a yearly average of the total mass of PM10 observed in El Alto and La Paz, respectively, but its contribution can increase up to 9 and 6% (3.4±1.6 µg m -3 and 2.1±1.2 µg m -3 ) during winter.…”