scholarly journals Significant reduction in abundance of peridomestic mosquitoes (Culicidae) and Culicoides midges (Ceratopogonidae): an additional benefit of a novel attract-and-kill intervention applied against Leishmania infantum transmission, in São Paulo Brazil

2020 ◽  
Author(s):  
Mikel A. González ◽  
Erin Dilger ◽  
María M. Ronderos ◽  
Gustavo R. Spinelli ◽  
Orin Courtenay ◽  
...  
Keyword(s):  
Sao Paulo ◽  
Sand Fly ◽  
Randomised Control Trial ◽  
São Paulo ◽  
Mosquito Abundance ◽  
Household Level ◽  
Sleeping Sites ◽  
Abundance And Distribution ◽  
And Control ◽  
The Impact

Abstract Background Following the long-term (42-month) evaluation of residual insecticide (co-located with sand fly pheromone) and insecticide-impregnated dog-collars in a randomised control trial (RCT) against leishmaniasis, we assessed the impact of these interventions on the peridomestic abundance and distribution of mosquitoes (Culicidae) and midges (Ceratopogonidae) in Western São Paulo, Brazil. Both of these Dipteran groups are vectors of diseases of medical and veterinary relevance to humans and domestic animals in Brazil. Methods The interventions in the 3-arm RCT: pheromone + insecticide (PI) (chicken roosts sprayed with microencapsulated lambda-cyhalothrin), dog-collars (DC) (dogs fitted with deltamethrin-impregnated collars), and control (C) (unexposed to pyrethroids) were extended by 12 months. During that time adult mosquitoes and midges were sampled at three household locations (inside human dwellings, dog sleeping sites, chicken roosts). Results We collected 3,145 culicids (9 genera mostly Culex spp.) distributed relatively uniformly across all 3 arms; 43.5% inside houses, 36.2% at chicken roosts and 20.3% at dog sleeping sites. We collected 11,464 Culicoides (at least 15 species) found mostly at chicken roosting sites (84.7%) compared with dog sleeping sites (12.2%) or houses (3.1%). Mosquitoes and Culicoides were predominant during the hot and rainy reason. Increased daytime temperature was significantly associated with increased mosquito abundance (z = 1.97; P = 0.049) but marginally associated with Culicoides abundance (z = 1.71; P = 0.087). There was no significant association with average rainfall for either group. Household-level mosquito and midge numbers were both significantly reduced by the PI intervention 56% (Incidence Rate Ratio, IRR = 0.54 [95% C.I. 0.30, 0.97], P ≤ 0.05] and 53% (IRR = 0.47 [0.26, 0.85], P ≤ 0.05), respectively. The abundance of both Dipteran groups at dog sleeping sites was largely unaffected by the PI and DC interventions. The PI intervention significantly reduced abundance of mosquitoes inside houses (41%) and at chicken roosting sites (48%) and reduced midge abundance by 51% in chicken roosting sites. Conclusions Sprayed insecticide at chicken roosting sites reduced the abundance of mosquitoes and midges at the peridomestic level while dog collars had no effect on numbers for any group.

scholarly journals Significant reduction in abundance of peridomestic mosquitoes (Culicidae) and Culicoides midges (Ceratopogonidae) after chemical intervention in western São Paulo, Brazil

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Mikel A. González ◽  
Erin Dilger ◽  
María M. Ronderos ◽  
Gustavo R. Spinelli ◽  
Orin Courtenay ◽  
...  
Keyword(s):  
Sao Paulo ◽  
Sand Fly ◽  
Randomised Control Trial ◽  
São Paulo ◽  
Biting Midges ◽  
Mosquito Abundance ◽  
Household Level ◽  
Control Intervention ◽  
Sleeping Sites ◽  
The Impact

Abstract Background We assessed the impact of two sand fly insecticide interventions (insecticide spraying and insecticide-impregnated dog collars) on the peridomestic abundance and distribution of mosquitoes (Culicidae) and biting midges (Ceratopogonidae) in western São Paulo (Brazil) in a long-term (42-month) evaluation. Both of these dipteran groups are vectors of diseases of medical and veterinary relevance to humans and domestic animals in Brazil. Methods The interventions in the 3-arm stratified randomised control trial were: pheromone + insecticide (PI) (chicken roosts were sprayed with microencapsulated lambda-cyhalothrin; pheromone lure has no effect on the Diptera pests studied here); dog-collars (DC) (dogs fitted with deltamethrin-impregnated collars); and control (C) (unexposed to pyrethroids) were extended by 12 months. During that time, adult mosquitoes and midges were sampled along 280 households at three household locations (inside human dwellings, dog sleeping sites and chicken roosts). Results We collected 3145 culicids (9 genera, 87.6% Culex spp.) distributed relatively uniformly across all 3 arms: 41.9% at chicken roosts; 37.7% inside houses; and 20.3% at dog sleeping sites. We collected 11,464 Culicoides (15 species) found mostly at chicken roosting sites (84.7%) compared with dog sleeping sites (12.9%) or houses (2.4%). Mosquitoes and Culicoides were most abundant during the hot and rainy season. Increased daytime temperature was marginally associated with increased mosquito abundance (Z = 1.97, P = 0.049) and Culicoides abundance (Z = 1.71, P = 0.087). There was no significant association with daily average rainfall for either group. Household-level mosquito and midge numbers were both significantly reduced by the PI intervention 56% [incidence rate ratio, IRR = 0.54 (95% CI: 0.30–0.97), P ≤ 0.05] and 53% [IRR = 0.47 (95% CI: 0.26–0.85), P ≤ 0.05], respectively, compared to the control intervention. The abundance of both dipteran groups at dog sleeping sites was largely unaffected by the PI and DC interventions. The PI intervention significantly reduced abundance of mosquitoes inside houses (41%) and at chicken roosting sites (48%) and reduced midge abundance by 51% in chicken roosting sites. Conclusions Sprayed insecticide at chicken roosting sites reduced the abundance of mosquitoes and midges at the peridomestic level while dog collars had no effect on numbers for any group.

scholarly journals Significant reduction in abundance of peridomestic mosquitoes (Culicidae) and Culicoides midges (Ceratopogonidae) after chemical intervention in western São Paulo, Brazil

2020 ◽  
Author(s):  
Mikel A. González ◽  
Erin Dilger ◽  
María M. Ronderos ◽  
Gustavo R. Spinelli ◽  
Orin Courtenay ◽  
...  
Keyword(s):  
Sao Paulo ◽  
Sand Fly ◽  
Randomised Control Trial ◽  
São Paulo ◽  
Biting Midges ◽  
Mosquito Abundance ◽  
Household Level ◽  
Control Intervention ◽  
Sleeping Sites ◽  
The Impact

Abstract Background: We assessed the impact of two sand fly insecticide interventions (insecticide spraying and insecticide-impregnated dog collars) on the peridomestic abundance and distribution of mosquitoes (Culicidae) and biting midges (Ceratopogonidae) in Western São Paulo (Brazil) in a long-term (42-month) evaluation. Both of these Dipteran groups are vectors of diseases of medical and veterinary relevance to humans and domestic animals in Brazil. Methods: The interventions in the 3-arm stratified randomised control trial were: pheromone + insecticide (PI) (chicken roosts were sprayed with microencapsulated lambda-cyhalothrin; pheromone lure has no effect on the Diptera pests studied here), dog-collars (DC) (dogs fitted with deltamethrin-impregnated collars), and control (C) (unexposed to pyrethroids) were extended by 12 months. During that time, adult mosquitoes and midges were sampled along 280 households at three household locations (inside human dwellings, dog sleeping sites, and chicken roosts).Results: We collected 3,145 culicids (9 genera, 87.6% Culex spp.) distributed relatively uniformly across all 3 arms; 41.9% at chicken roosts, 37.7% inside houses, and 20.3% at dog sleeping sites. We collected 11,464 Culicoides (15 species) found mostly at chicken roosting sites (84.7%) compared with dog sleeping sites (12.9%) or houses (2.4%). Mosquitoes and Culicoides were most abundant during the hot and rainy season. Increased daytime temperature was marginally associated with increased mosquito abundance (z = 1.97; P = 0.049) and Culicoides abundance (z = 1.71; P = 0.087). There was no significant association with daily average rainfall for either group. Household-level mosquito and midge numbers were both significantly reduced by the PI intervention 56% [Incidence Rate Ratio, IRR = 0.54 (95% C.I. 0.30, 0.97), P ≤ 0.05] and 53% [IRR = 0.47 (0.26, 0.85), P ≤ 0.05], respectively, compared to the control intervention. The abundance of both Dipteran groups at dog sleeping sites was largely unaffected by the PI and DC interventions. The PI intervention significantly reduced abundance of mosquitoes inside houses (41%) and at chicken roosting sites (48%) and reduced midge abundance by 51% in chicken roosting sites.Conclusions: Sprayed insecticide at chicken roosting sites reduced the abundance of mosquitoes and midges at the peridomestic level while dog collars had no effect on numbers for any group.

scholarly journals Significant reduction in abundance of peridomestic mosquitoes (Culicidae) and Culicoides midges (Ceratopogonidae) after chemical intervention in western São Paulo, Brazil

2020 ◽  
Author(s):  
Mikel A. González ◽  
Erin Dilger ◽  
María M. Ronderos ◽  
Gustavo R. Spinelli ◽  
Orin Courtenay ◽  
...  
Keyword(s):  
Sao Paulo ◽  
Sand Fly ◽  
Randomised Control Trial ◽  
São Paulo ◽  
Biting Midges ◽  
Mosquito Abundance ◽  
Household Level ◽  
Control Intervention ◽  
Sleeping Sites ◽  
The Impact

Abstract Background: We assessed the impact of two sand fly insecticide interventions (insecticide spraying and insecticide-impregnated dog collars) on the peridomestic abundance and distribution of mosquitoes (Culicidae) and biting midges (Ceratopogonidae) in western São Paulo (Brazil) in a long-term (42-month) evaluation. Both of these dipteran groups are vectors of diseases of medical and veterinary relevance to humans and domestic animals in Brazil.Methods: The interventions in the 3-arm stratified randomised control trial were: pheromone + insecticide (PI) (chicken roosts were sprayed with microencapsulated lambda-cyhalothrin; pheromone lure has no effect on the Diptera pests studied here); dog-collars (DC) (dogs fitted with deltamethrin-impregnated collars); and control (C) (unexposed to pyrethroids) were extended by 12 months. During that time, adult mosquitoes and midges were sampled along 280 households at three household locations (inside human dwellings, dog sleeping sites and chicken roosts).Results: We collected 3145 culicids (9 genera, 87.6% Culex spp.) distributed relatively uniformly across all 3 arms: 41.9% at chicken roosts; 37.7% inside houses; and 20.3% at dog sleeping sites. We collected 11,464 Culicoides (15 species) found mostly at chicken roosting sites (84.7%) compared with dog sleeping sites (12.9%) or houses (2.4%). Mosquitoes and Culicoides were most abundant during the hot and rainy season. Increased daytime temperature was marginally associated with increased mosquito abundance (Z = 1.97, P = 0.049) and Culicoides abundance (Z = 1.71, P = 0.087). There was no significant association with daily average rainfall for either group. Household-level mosquito and midge numbers were both significantly reduced by the PI intervention 56% [incidence rate ratio, IRR = 0.54 (95% CI: 0.30–0.97), P ≤ 0.05] and 53% [IRR = 0.47 (95% CI: 0.26–0.85), P ≤ 0.05], respectively, compared to the control intervention. The abundance of both dipteran groups at dog sleeping sites was largely unaffected by the PI and DC interventions. The PI intervention significantly reduced abundance of mosquitoes inside houses (41%) and at chicken roosting sites (48%) and reduced midge abundance by 51% in chicken roosting sites.Conclusions: Sprayed insecticide at chicken roosting sites reduced the abundance of mosquitoes and midges at the peridomestic level while dog collars had no effect on numbers for any group.

scholarly journals Significant reduction in abundance of peridomestic mosquitoes (Culicidae) and Culicoides midges (Ceratopogonidae) after insecticide intervention in western São Paulo, Brazil

2020 ◽  
Author(s):  
Mikel A. González ◽  
Erin Dilger ◽  
María M. Ronderos ◽  
Gustavo R. Spinelli ◽  
Orin Courtenay ◽  
...  
Keyword(s):  
Sand Fly ◽  
Randomised Control Trial ◽  
Biting Midges ◽  
Study Objective ◽  
Mosquito Abundance ◽  
Household Level ◽  
Veterinary Importance ◽  
Sleeping Sites ◽  
Abundance And Distribution ◽  
The Impact

Abstract Background: We assessed the impact of two long-term interventions (insecticide spraying and insecticide-impregnated dog collars), previously directed against sand flies, on the abundance and distribution of mosquitoes (Culicidae) and biting midges (Ceratopogonidae). Both groups are of medical and veterinary importance in Brazil. Our objective was to determine the effect of the sand fly interventions on other biting Diptera.Methods: This study retained the original stratified randomised control trial design but was extended for 12 months. We included the 2 original intervention arms: chicken roosts sprayed with microencapsulated lambda-cyhalothrin and dogs fitted with deltamethrin-impregnated collars and a control arm with no insecticide. Adult mosquitoes and midges were sampled in 280 households at three locations (inside human dwellings, dog sleeping sites, chicken roosts). To maintain the integrity of the study objective we placed sand fly pheromone in the sprayed-insecticide arm. The sand fly pheromone has no effect on the behaviour of culicids or Culicoides.Results: We collected 3,145 culicids (9 genera, 87.6% Culex spp.) distributed relatively uniformly across all 3 arms; 41.9% at chicken roosts, 37.7% inside houses, and 20.3% at dog sleeping sites. We collected 11,464 Culicoides (15 species) found mostly at chicken roosting sites (84.7%) compared with dog sleeping sites (12.9%) or houses (2.4%). Mosquitoes and Culicoides were most abundant during the hot and rainy season. Increased daytime temperature was marginally associated with increased mosquito abundance (z=1.97; P=0.049) and Culicoides abundance (z=1.71; P=0.087). There was no significant association with daily average rainfall for either group. Household-level mosquito and midge numbers were both significantly reduced by the sprayed insecticide intervention 56% [Incidence Rate Ratio, IRR=0.54 (95% C.I. 0.30, 0.97), P≤0.05] and 53% [IRR=0.47 (0.26, 0.85), P≤0.05], respectively, compared to the control. The abundance of both Dipteran groups at dog sleeping sites was unaffected by either intervention. The sprayed insecticide significantly reduced abundance of mosquitoes inside houses (41%), at chicken roosting sites (48%) and reduced midge abundance by 51% in chicken roosting sites.Conclusions: Insecticide sprayed at chicken roosting sites reduced the abundance of mosquitoes and midges at the peridomestic level. Dog collars had no effect on numbers of any group.

scholarly journals Impact of nonpharmaceutical governmental strategies for prevention and control of COVID-19 in São Paulo State, Brazil.

2020 ◽  
Author(s):  
Cristiane Ravagnani Fortaleza ◽  
Thomas Nogueira Vilches ◽  
Gabriel Berg de Almeida ◽  
Claudia Pio Ferreira ◽  
Rejane Maria Tommasini Grotto ◽  
...  
Keyword(s):  
Interrupted Time Series ◽  
Sao Paulo ◽  
Reproductive Number ◽  
São Paulo ◽  
Social Distancing ◽  
Paulo State ◽  
São Paulo State ◽  
Time Series Analyses ◽  
And Control ◽  
The Impact

Interrupted time series analyses (ITSA) were performed to measure the impact of social distancing policies (instituted 22/03/2020) and subsequent mandatory masking in the community (instituted 04/05/2020) on the incidence and effective reproductive number (Rt) of COVID-19 in São Paulo State, Brazil. Overall, the impact of social distancing both on incidence and Rt was greater than the incremental effect of mandatory masking. Those findings may reflect either a small impact of face masking or the loosening of social distancing after mandatory use of masks.

THE IMPACT OF DIFFERENT URBAN LAND USE TYPES ON AIR POLLUTION IN THE MEGACITY OF SÃO PAULO

2020 ◽  
Vol 7 (1) ◽  
pp. 91
Author(s):  
Júlio Barboza Chiquetto ◽  
Maria Elisa Siqueira Silva ◽  
Rita Yuri Ynoue ◽  
Flávia Noronha Dutra Ribieiro ◽  
Débora Souza Alvim ◽  
...  
Keyword(s):  
Land Use ◽  
Air Pollution ◽  
Urban Land ◽  
Sao Paulo ◽  
Urban Land Use ◽  
São Paulo ◽  
Land Use Types ◽  
The Impact

A poluição do ar é influenciada por fatores naturais e antropogênicos. Quatro pontos de monitoramento (veicular, comercial, residencial e background urbano (BGU))da poluição do ar em São Paulo foram avaliados durante 16 anos, revelando diferenças significativas devidoao uso do solo em todas as escalas temporais. Na escala diurna, as concentrações de poluentes primários são duas vezes mais altas nos pontos veicular e residencial do que no ponto BGU, onde a concentração de ozonio (O3) é 50% mais alta. Na escala sazonal, as concentrações de monóxido de carbono(CO) variaram em 80% devido ao uso do solo, e 55% pela sazonalidade.As variações sazonais ede uso do solo exercem impactos similares nas concentrações de O3 e monóxido de nitrogênio (NO). Para o material particulado grosso (MP10) e o dióxido de nitrogênio(NO2), as variações sazonais são mais intensas do que as por uso do solo. Na série temporal de 16 anos, o ponto BGU apresentou correlações mais fortes e significativas entre a média mensal de ondas longas (ROL) e o O3 (0,48) e o MP10 (0,37), comparadas ao ponto veicular (0,33 e 0,22, respectivamente). Estes resultados confirmam que o uso do solo urbano tem um papel significativo na concentração de poluentes em todas as escalas de análise, embora a sua influência se torne menos pronunciada em escalas maiores, conforme a qualidade do ar transita de um sistema antropogênico para um sistema natural. Isto poderá auxiliar decisões sobre políticas públicas em megacidades envolvendo a modificação do uso do solo.

scholarly journals Modelling the impact of delaying vaccination against SARS-CoV-2 assuming unlimited vaccine supply

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Marcos Amaku ◽  
Dimas Tadeu Covas ◽  
Francisco Antonio Bezerra Coutinho ◽  
Raymundo Soares Azevedo ◽  
Eduardo Massad
Keyword(s):  
Mathematical Model ◽  
Vaccination Campaign ◽  
Vaccination Rate ◽  
Sao Paulo ◽  
The State ◽  
São Paulo ◽  
Health Authorities ◽  
The World ◽  
The Moment ◽  
The Impact

Abstract Background At the moment we have more than 177 million cases and 3.8 million deaths (as of June 2021) around the world and vaccination represents the only hope to control the pandemic. Imperfections in planning vaccine acquisition and difficulties in implementing distribution among the population, however, have hampered the control of the virus so far. Methods We propose a new mathematical model to estimate the impact of vaccination delay against the 2019 coronavirus disease (COVID-19) on the number of cases and deaths due to the disease in Brazil. We apply the model to Brazil as a whole and to the State of Sao Paulo, the most affected by COVID-19 in Brazil. We simulated the model for the populations of the State of Sao Paulo and Brazil as a whole, varying the scenarios related to vaccine efficacy and compliance from the populations. Results The model projects that, in the absence of vaccination, almost 170 thousand deaths and more than 350 thousand deaths will occur by the end of 2021 for Sao Paulo and Brazil, respectively. If in contrast, Sao Paulo and Brazil had enough vaccine supply and so started a vaccination campaign in January with the maximum vaccination rate, compliance and efficacy, they could have averted more than 112 thousand deaths and 127 thousand deaths, respectively. In addition, for each month of delay the number of deaths increases monotonically in a logarithmic fashion, for both the State of Sao Paulo and Brazil as a whole. Conclusions Our model shows that the current delay in the vaccination schedules that is observed in many countries has serious consequences in terms of mortality by the disease and should serve as an alert to health authorities to speed the process up such that the highest number of people to be immunized is reached in the shortest period of time.

scholarly journals The Impact of COVID-19 on Urban Agriculture in São Paulo, Brazil

2021 ◽  
Vol 13 (11) ◽  
pp. 6185
Author(s):  
André Ruoppolo Biazoti ◽  
Angélica Campos Nakamura ◽  
Gustavo Nagib ◽  
Vitória Oliveira Pereira de Souza Leão ◽  
Giulia Giacchè ◽  
...  
Keyword(s):  
Urban Agriculture ◽  
Technical Assistance ◽  
Community Gardens ◽  
Sao Paulo ◽  
Food Chains ◽  
São Paulo ◽  
Sales Channels ◽  
Paulo State ◽  
The Impact ◽  
The City

During the initial months of the COVID-19 pandemic, farmers worldwide were greatly affected by disruptions in the food chain. In 2020, São Paulo city experienced most of the effects of the pandemic in Brazil, with 15,587 deaths through December 2020. Here, we describe the impacts of COVID-19 on urban agriculture (UA) in São Paulo from April to August 2020. We analyzed two governmental surveys of 2100 farmers from São Paulo state and 148 from São Paulo city and two qualitative surveys of volunteers from ten community gardens and seven urban farmers. Our data showed that 50% of the farmers were impacted by the pandemic with drops in sales, especially those that depended on intermediaries. Some farmers in the city adapted to novel sales channels, but 22% claimed that obtaining inputs became difficult. No municipal support was provided to UA in São Paulo, and pre-existing issues were exacerbated. Work on community gardens decreased, but no garden permanently closed. Post COVID-19, UA will have the challenge of maintaining local food chains established during the pandemic. Due to the increase in the price of inputs and the lack of technical assistance, governmental efforts should be implemented to support UA.

scholarly journals Relationship between preterm birth and air pollution in Santos, Sao Paulo, Brazil

2020 ◽  
Vol 30 (Supplement_5) ◽  
Author(s):  
M E L Brandao ◽  
B A L F Braga ◽  
M L C Martins ◽  
P L A A Pereira
Keyword(s):  
Air Pollution ◽  
Preterm Birth ◽  
Air Pollutants ◽  
First Trimester ◽  
Sao Paulo ◽  
São Paulo ◽  
Air Humidity ◽  
Relative Air Humidity ◽  
The Impact ◽  
Fourth Quartile

Abstract Santos is a seaboard Brazilian city recognized by its port activity where the road and rail infrastructure along with the large transportation operation, displays an important factor to contribute with all kinds of toxic and air pollutants. Recent studies have suggested associations between air pollution and various birth outcomes. Pollutant gases such as NOx, O3 and particulate matter PM2,5, PM10 have been cited as factors involved in such outcomes. The present study aims to assess the relationship between atmospheric pollutants and perinatal outcomes in the city of Santos from Jan. 2012 to Dec. 2015. Cross-sectional study that analyzed 10.319 singleton births in an area set with 2 km radius of the monitoring stations. Birth weight and information on mother and pregnancy were obtained at the Brazilian “Born Alive National Information System”. Daily records of air pollutants (PM10, PM2.5, NO2 and O3), temperature and relative air humidity, for the study period, were obtained from São Paulo State Environmental Agency (CETESB). Associations between preterm birth and air pollutants mean levels at each gestational trimester were investigated using multiple logistic regression model controlled by the variables: infant sex, type of delivery, maternal education. prenatal care, and number of previous live births, temperature and relative air humidity. NO2 e PM2,5 was not associated with preterm birth. O3 was significantly associated in the first trimester in the fourth quartile (OR = 1,47 CI 95% 1,05; 2,07). PM10 was significantly associated in the first trimester for the fourth quartile (OR = 1,28 CI 95% 1,00; 1,64), second trimester for the second quartile (OR = 1,37 CI 95% 1,07; 1,77). Conclusions the results shows evidence that maternal exposure to air pollution especially during the first trimester of pregnancy may contribute to preterm birth. Further actions are needed towards controlling air pollution are strongly recommended for promoting early-life health. Key messages This is the first research of this kind that was made in Santos. It brings important evidence of the impact in the life of the population, especially those whose is not even born yet. It can be used as a resource to guide public policies in health, especially the guidelines that dictate the concentration of air pollutants and air quality.

scholarly journals Impact of vehicular emissions on the formation of fine particles in the Sao Paulo Metropolitan Area: a numerical study with the WRF-Chem model

2016 ◽  
Vol 16 (2) ◽  
pp. 777-797 ◽  
Author(s):  
A Vara-Vela ◽  
M. F. Andrade ◽  
P. Kumar ◽  
R. Y. Ynoue ◽  
A. G. Muñoz
Keyword(s):  
Size Distribution ◽  
Metropolitan Area ◽  
Atmospheric Aerosols ◽  
Fine Particles ◽  
Sao Paulo ◽  
Vehicular Emissions ◽  
São Paulo ◽  
Mass Size Distribution ◽  
Mass Size ◽  
The Impact

Abstract. The objective of this work is to evaluate the impact of vehicular emissions on the formation of fine particles (PM2.5;  ≤  2.5 µm in diameter) in the Sao Paulo Metropolitan Area (SPMA) in Brazil, where ethanol is used intensively as a fuel in road vehicles. The Weather Research and Forecasting with Chemistry (WRF-Chem) model, which simulates feedbacks between meteorological variables and chemical species, is used as a photochemical modelling tool to describe the physico-chemical processes leading to the evolution of number and mass size distribution of particles through gas-to-particle conversion. A vehicular emission model based on statistical information of vehicular activity is applied to simulate vehicular emissions over the studied area. The simulation has been performed for a 1-month period (7 August–6 September 2012) to cover the availability of experimental data from the NUANCE-SPS (Narrowing the Uncertainties on Aerosol and Climate Changes in Sao Paulo State) project that aims to characterize emissions of atmospheric aerosols in the SPMA. The availability of experimental measurements of atmospheric aerosols and the application of the WRF-Chem model made it possible to represent some of the most important properties of fine particles in the SPMA such as the mass size distribution and chemical composition, besides allowing us to evaluate its formation potential through the gas-to-particle conversion processes. Results show that the emission of primary gases, mostly from vehicles, led to a production of secondary particles between 20 and 30 % in relation to the total mass concentration of PM2.5 in the downtown SPMA. Each of PM2.5 and primary natural aerosol (dust and sea salt) contributed with 40–50 % of the total PM10 (i.e. those  ≤  10 µm in diameter) concentration. Over 40 % of the formation of fine particles, by mass, was due to the emission of hydrocarbons, mainly aromatics. Furthermore, an increase in the number of small particles impaired the ultraviolet radiation and induced a decrease in ozone formation. The ground-level O3 concentration decreased by about 2 % when the aerosol-radiation feedback is taken into account.

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