**3. Ground-level monitoring of particulates**

276 Atmospheric Aerosols – Regional Characteristics – Chemistry and Physics

which about 50% operate within the RMSP [9].

islands and increased concentrations of PM10.

**2. Meteorology and climatology of the State of São Paulo** 

accumulation of pollutants in the atmosphere of the region [25].

In the State of São Paulo, the first aerosol measurements began in Cubatão [13], and within the metropolitan area of São Paulo, notorious for its traffic emissions [14]. In terms of morphology, São Paulo is among the world's five largest cities, and is sixth largest in terms of population [15], with about 11,3 million inhabitants. The population of the Metropolitan Region of São Paulo (RMSP), which includes peripheral urban areas, reached an estimated 19,9 million persons in 2009 [16]. Human activities including road transport and industry now exert an enormous impact on air quality in the region, and therefore on the health of the population [17]. The total fleet of vehicles (cars, buses, trucks and motorcycles, powered by gasoline, ethanol and diesel) in the State of São Paulo exceeded 12,8 million in 2011, of

Observations from the Brazilian Lightning Detection Networks (RINDAT [18] and BrasilDAT at ELAT/INPE [19]) have shown a significantly higher lightning frequency over the RMSP and other large urban complexes within the State since the inception of the RINDAT Lightning Network in 1999 [20, 21]. This prompted a study of the impact of anthropogenic emissions on the frequency of lightning [22], showing a distinct increase of cloud-to-ground flashes, not only over the RMSP, but also over other large cities and densely populated or industrialized regions in the State, correlated to the occurrence of heat

Since the meteorology of a region has a major impact on the dispersion or accumulation of pollutants, a brief characterization of the climate is appropriate. The State of São Paulo is located between the latitudes of about 20 and 25 South (Figure 1), thus falling into the transition zone from a tropical to a subtropical climate, with an annual rainfall total ranging between 1250 and 1650 mm in the interior, increasing to 1850 mm over the narrow coastal strip [23]. The year can be roughly divided into two periods, *viz.*, the rainy season from October to March, when most of the rain is produced by convective storms, and the dry winter months from April to September. During the rainy season, conditions are more representative of the tropical climate, with the occasional occurrence of a South Atlantic Convergence Zone (SACZ), which can be identified from satellite images as a cloud band with orientation northwest to southeast, extending from the southern region of Amazônia into the central region of the South Atlantic Ocean [24]. The SACZ situations can last more or less continuously from 4 days to more than one month and are extremely efficient producers of rain in the form of tropical thunderstorms, with accompanying high humidity. During the relatively dry winter months, the climatic conditions are more typical of the subtropics, with only occasional heavy rainfalls being caused by the passage of baroclinic systems (mostly cold fronts), moving from southwest to northeast across the State, but for the remaining time, the weather is dominated by a high pressure system, resulting in elevated temperatures, with low humidity and high stability in the Planetary Boundary Layer, favoring the Regular monitoring of air pollutants under the auspices of the Companhia de Tecnologia de Saneamento Ambiental (CETESB), the air quality "watchdog" in the State of São Paulo, started in the 70s, but a fully automatic monitoring network was only installed in 2000. Since then, observations are available in real time [30]. In 2001, 29 automatic stations, the majority in the RMSP, were already in operation [31]. From 2008 onwards, the automatic monitoring network was significantly expanded. In 2011, 42 monitoring stations in 28 towns were in operation, 19 in the RMSP and 23 in the remaining parts of the State [9]. The majority of the stations monitor particulate matter (PM10), NO, NO2, NOx and O3, as well as meteorological parameters, while a few also measure PM2.5, SO2 and CO. The automatic air quality monitoring network is shown in Figure 3. Additionally, CETESB also maintained a network of 41 manual monitoring stations during 2011, where measurements are made of PM2.5, PM10, TSP (Total Suspended Particulates), black smoke and SO2, in various combinations [9]. Aerosol mass concentrations are determined using either β-attenuation instruments (automatic stations) or gravimetric and reflectometric techniques (manual stations).

In accordance with recommendations of the World Health Organization [32], CETESB defines 5 levels of air quality: "Boa" (good), "Regular" (regular), "Inadequada" (insufficient), "Má" (bad) and "Péssimo" (extremely bad), the highest being invoked if one of the monitored pollutants exceeds the pre-defined threshold. The national air quality standards are defined in CONAMA Resolution No. 03/90 (Table 2 in [9]).

PM10 and TSP measurements are available since 1984 and 1985, respectively [31], although initially only from very few stations in the interior of the State, but gradually increasing to 41 and 11, respectively, in 2011 [9]. Figure 4 shows the year-to-year variation of annual mean PM10 concentrations against the National Air Quality Standard (PQAr) for the RMSP and two sites in Cubatão (Figure 3, Nos. 24 and 25), which is one of the major industrial hubs in Brazil, where one site is located within the industrial suburb (No. 25) and the other in the

town centre (No. 24). A significant reduction of mean annual PM10 concentrations can be noticed from 1998 onwards, confirming the success of implementation of stringent air quality control measures, administered by CETESB. However, within the industrial suburb, confined in a valley, concentrations are still about twice the PQAr. A detailed description of Cubatão, its industrial activities and their location are found in [33]. More details on current PM10 and TSP concentrations are provided in Section 4.3.

Review of Aerosol Observations by Lidar and Chemical Analysis in the State of São Paulo, Brazil 279

Figure 5 demonstrates that the air quality in the interior of the State from 2002 to 2011, when a reasonable number of monitoring sites were already in operation [9], was generally well below the annual standard of 50 μg.m-3 for PM10, with the exception of Santa Gertrudes, just south of Rio Claro (Figure 6), where several large ceramic industries are located, notorious for emitting large quantities of aerosols. At two other monitoring sites, annual means were close to the Annual Standard. At Limeira mixed industrial activities range from metallurgical, through cellulose to ceramics, besides sugar cane and orange production and processing plants. Limeira and Santa Gertrudes are medium-sized industrial towns, about 20 and 40 km northwest of Americana (Figure 3, No. 52). The other site is in Piracicaba (Figure 3, No. 77), which also hosts mixed industrial activities, including a significant petrochemical plant. However, the exceedance in 2011 was most likely caused by major road

Although annual mean concentrations of PM in the State of São Paulo seem to be quite acceptable, it is obvious that violations of the daily Air Quality Standard do occur occasionally in several towns of the interior and within the RMSP. Comprehensive annual and specialized technical reports and publications on the air quality in the State of São

**Figure 5.** Year to year variation of PM10 from 2002 -2011 for monitoring sites in the interior of the State

of São Paulo (after [9]). PQAr = 50 μg.m-3 represents the Annual Standard.

construction works in the immediate vicinity of the monitoring site [9].

Paulo, including detailed monitoring results, are available online [9].

**Figure 3.** CETESB network of automatic monitoring stations in 2011. The shading indicates the principal land use in four schematic regions of the State, directly related to the type of emissions. Adapted from [9].

**Figure 4.** Year to year variation of PM10 from 1984 – 2011 for the RMSP and Cubatão. The data were extracted from [9, 31]. PQAr = 50 μg.m-3 represents the Annual Standard.

Figure 5 demonstrates that the air quality in the interior of the State from 2002 to 2011, when a reasonable number of monitoring sites were already in operation [9], was generally well below the annual standard of 50 μg.m-3 for PM10, with the exception of Santa Gertrudes, just south of Rio Claro (Figure 6), where several large ceramic industries are located, notorious for emitting large quantities of aerosols. At two other monitoring sites, annual means were close to the Annual Standard. At Limeira mixed industrial activities range from metallurgical, through cellulose to ceramics, besides sugar cane and orange production and processing plants. Limeira and Santa Gertrudes are medium-sized industrial towns, about 20 and 40 km northwest of Americana (Figure 3, No. 52). The other site is in Piracicaba (Figure 3, No. 77), which also hosts mixed industrial activities, including a significant petrochemical plant. However, the exceedance in 2011 was most likely caused by major road construction works in the immediate vicinity of the monitoring site [9].

278 Atmospheric Aerosols – Regional Characteristics – Chemistry and Physics

PM10 and TSP concentrations are provided in Section 4.3.

Adapted from [9].

**PM10 (µg.m-3)**

town centre (No. 24). A significant reduction of mean annual PM10 concentrations can be noticed from 1998 onwards, confirming the success of implementation of stringent air quality control measures, administered by CETESB. However, within the industrial suburb, confined in a valley, concentrations are still about twice the PQAr. A detailed description of Cubatão, its industrial activities and their location are found in [33]. More details on current

**Figure 3.** CETESB network of automatic monitoring stations in 2011. The shading indicates the principal land use in four schematic regions of the State, directly related to the type of emissions.

> **RMSP Cubatão-Centro Cubatão-Industrial PQAr (Annual Standard)**

**Figure 4.** Year to year variation of PM10 from 1984 – 2011 for the RMSP and Cubatão. The data were

**84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 YEAR**

extracted from [9, 31]. PQAr = 50 μg.m-3 represents the Annual Standard.

Although annual mean concentrations of PM in the State of São Paulo seem to be quite acceptable, it is obvious that violations of the daily Air Quality Standard do occur occasionally in several towns of the interior and within the RMSP. Comprehensive annual and specialized technical reports and publications on the air quality in the State of São Paulo, including detailed monitoring results, are available online [9].

**Figure 5.** Year to year variation of PM10 from 2002 -2011 for monitoring sites in the interior of the State of São Paulo (after [9]). PQAr = 50 μg.m-3 represents the Annual Standard.

Review of Aerosol Observations by Lidar and Chemical Analysis in the State of São Paulo, Brazil 281

to the chemical data. Dry deposition fluxes were estimated using the measured atmospheric concentrations together with dry deposition velocities of gases and aerosols to different surface types, including tropical forest, savannah, sugar cane, pine, eucalyptus, orange, coffee, pasture and water. The annual cycle in deposition, to a sugar cane surface, of reactive nitrogen and sulphur in the gaseous, aerosol and dissolved phases is illustrated in Figure 7.

**Figure 7.** Annual cycle in deposition fluxes to a sugar cane surface of: **(a)** sulphur in gaseous (S(g)), aerosol (S(a)) and rainwater (S(p)) phases; **(b)** nitrogen in gaseous (N(g)), aerosol (N(a)) and rainwater (N(p))

The sugar cane industry has a major impact on air quality and the characteristics of the atmospheric aerosol. During the dry season (May to October), the burning of the cane, a prerequisite of manual harvesting, has for many years resulted in very large emissions of pollutants, including high carbon content aerosols. These particles contain water-soluble organic carbon (WSOC), anions (sulphates, nitrates and chlorides), cations (potassium, ammonium, calcium, magnesium, sodium), black carbon (BC), insoluble organic carbon and trace metals. Carbonaceous material comprises the bulk of the aerosol mass, especially in fine particles [5-7, 35-39]. In 2004, the annual emission of nitrogen oxides (NOx) from sugar cane burning in Sao Paulo State was in excess of 45 Gg.N [40]. This is not only indicative of the scale of the emissions, but also of their potential for formation of secondary aerosols

In 2011, annual mean PM10 concentrations measured at automatic monitoring stations in the agro-industrial interior of São Paulo State were in the range 23-91 g.m-3, with the highest

phases. Primary y-axes: gas and rainwater; secondary y-axes: aerosol. Data for Araraquara.

(containing nitrates, amongst other components).

**Figure 6.** Aerosol monitoring sites in the State of São Paulo (except CETESB network) and 240 km ranges of IPMet's radars in Presidente Prudente (PPR) and Bauru (BRU). Sites from where lidar measurements are available are marked with x.
