**6.1. Impact of aerosols on human health**

The impact of anthropogenic aerosols on human health has been acknowledged in both metropolitan and rural regions [93, and references therein]. In general terms, as pointed out in [93], in recent years the population of São Paulo State has suffered from either acute (short-term, high concentration) or chronic (long-term, lower concentration) exposure to particulate air pollutants, depending on location. In rural regions, there is acute exposure to high concentrations of biomass burning particulates present in plumes, as well as chronic exposure to these aerosols on a regional basis throughout the dry season. In metropolitan São Paulo, there is chronic exposure to particulates derived from road transport and industrial emissions, together with periodic acute exposure to extremely high levels of pollutants under conditions of thermal inversions and stationary air masses [94-96].

Review of Aerosol Observations by Lidar and Chemical Analysis in the State of São Paulo, Brazil 307

increased pressure for mechanization of harvesting, since the mechanized process does not necessarily require prior burning of the crop. Nonetheless, until recently burning has continued to be employed in mechanized areas (using simpler machinery) because it can

A clear relationship between particulate air pollution and the occurrence of respiratory illness in sugar cane burning regions of the State has been reported [45, 113-116]. Particulate material from sugar cane burning was demonstrated to have the greatest detrimental effect on the respiratory systems of the most sensitive population groups. Cançado *et al.* [45] measured black carbon and trace elements in fine and coarse aerosol fractions, and related the concentrations to daily records of hospital admissions for respiratory illness of children (<13 years old) and the elderly (>64 years), in the town of Piracicaba. Increases of 10,2 g.m-3 (PM2.5) and 42,9 g.m-3 (PM10) were associated with increases in hospital admissions of 21,4%

Carcinogenic and mutagenic compounds are emitted during biomass burning [109]. Concentrations of PAHs in a rural sugar cane burning region during the harvest period were in the range 0,5-8,6 ng.m-3 [38]. The mutagenic activity of PM10 was much higher during the harvest season, when the PM10 concentration was 67 g.m-3, and the mutagenic potency was 13,45 revertants m-3. During the summer (non-burning period), the PM10 concentration was 20,9 g.m-3, and the mutagenic potency was 1,30 revertants

Aerosols derived from all of the sources described above are able to alter the radiative properties of the troposphere, and can modify the processes that lead to the development of cloud condensation nuclei, cloud droplets, and ultimately precipitation [118-120]. The magnitudes of these effects depend on the size distribution, number concentration and chemical composition of the particles, and can therefore vary widely within the same

Dufek and Ambrizzi [121] used daily precipitation data collected at 59 locations in São Paulo State to investigate rainfall trends for the period 1950-1999. Although some of the findings were contradictory, an overall trend towards a wetter climate was identified, with rainfall concentrated into a smaller number of more intense events. It was suggested that these changes could be related to the presence of biomass burning aerosols, as well as changes in land use. Evidence that the aerosols probably act as cloud condensation nuclei was provided in [122], where a relationship was identified between water-soluble organic carbon (WSOC)

An important point is that sugar cane production in São Paulo State has increased over this period. Between the 1990/91 and 2000/01 seasons, the harvest increased from 132 Mt to 194 Mt [123]. It can therefore be supposed that there was also a large increase in emissions of aerosols from the burning of the crop, since manual harvesting of the cane (which requires

in the particles and dissolved organic carbon (DOC) in rainwater.

improve economic efficiency by around 30-40% [50, 112].

(children) and 31,03% (elderly people).

**6.2. Impact of aerosols on rainfall** 

m-3 [117].

region.

There have been many studies of the correlation between aerosol concentrations and human health impacts in the metropolitan regions, especially in São Paulo city [97-102]. Typical effects include asthma and pneumonia, as well as other cardiovascular and respiratory symptoms. Increased levels of PM10 were associated with increases of 6,7% and 2,2% in hospital admissions of children due to respiratory illness [96, 103]. Increments of 10 g.m-3 in PM10 concentrations resulted in increases in hospital admissions of between 0,9% and 6,7% in Sao Paulo [97, 103-105]. In the elderly, a 5,4% increase in the number of deaths was linked to a 10 g.m-3 increase in PM10 [105]. Industrial emissions in Cubatão have been found to seriously affect the lung function of children, with respiratory airflow rates correlated with PM10 concentrations obtained for the preceding month [106].

Bourotte *et al.* [56] investigated the relationships between peak expiratory flow (PEF) measurements and soluble ions in fine and coarse aerosols, and found a negative correlation between PEF and the coarse fraction ions Cl- , Na+, Mg2+ and NH4+, as well as between PEF and fine fraction Mg2+. The findings suggested that increased levels of coarse particles could be of especial concern for asthmatic individuals.

In these heavily polluted regions, atmospheric particles contain components known to be carcinogenic and mutagenic, including ketones, aldehydes, quinolines, carboxylic acids, polycyclic aromatic compounds (PAHs), and nitro-PAHs. These substances have been associated with exhaust emissions from road vehicles in southeast Brazil [69, 107-109]. Benzo[a]pyrene equivalent values suggest that the cancer risk is greater for the São Paulo city aerosol than elsewhere in the State, although concentrations may not exceed World Health Organization guidelines [65].

Biomass burning emissions in rural regions also have a recognized influence on human health, as well as environmental impacts including modification of nutrient cycling [10, 11, 47], and effects on climate including alterations of the radiative properties of the lower atmosphere, cloud formation and precipitation [110, 111]. For these reasons, as well as due to the need to meet certification requirements of importing countries, there has been increased pressure for mechanization of harvesting, since the mechanized process does not necessarily require prior burning of the crop. Nonetheless, until recently burning has continued to be employed in mechanized areas (using simpler machinery) because it can improve economic efficiency by around 30-40% [50, 112].

A clear relationship between particulate air pollution and the occurrence of respiratory illness in sugar cane burning regions of the State has been reported [45, 113-116]. Particulate material from sugar cane burning was demonstrated to have the greatest detrimental effect on the respiratory systems of the most sensitive population groups. Cançado *et al.* [45] measured black carbon and trace elements in fine and coarse aerosol fractions, and related the concentrations to daily records of hospital admissions for respiratory illness of children (<13 years old) and the elderly (>64 years), in the town of Piracicaba. Increases of 10,2 g.m-3 (PM2.5) and 42,9 g.m-3 (PM10) were associated with increases in hospital admissions of 21,4% (children) and 31,03% (elderly people).

Carcinogenic and mutagenic compounds are emitted during biomass burning [109]. Concentrations of PAHs in a rural sugar cane burning region during the harvest period were in the range 0,5-8,6 ng.m-3 [38]. The mutagenic activity of PM10 was much higher during the harvest season, when the PM10 concentration was 67 g.m-3, and the mutagenic potency was 13,45 revertants m-3. During the summer (non-burning period), the PM10 concentration was 20,9 g.m-3, and the mutagenic potency was 1,30 revertants m-3 [117].
