Modelling exposure of workers, residents and bystanders to vapour of plant protection products after application to crops F. van den Berg a, ⁎, C.M.J. Jacobs a , M.C. Butler Ellis b , P. Spanoghe c , K. Doan Ngoc c , G. Fragkoulis d a Alterra Wageningen UR, Wageningen, Netherlands b Silsoe Spray Application Unit, Silsoe, UK c Laboratory of Crop Protection Chemistry, Ghent University, Belgium d Istituto di Chimica Agraria ed Ambientale, Università Cattolica del Sacro Cuore, Piacenza, Italy HIGHLIGHTS • A pesticide volatilisation model has been coupled to a dispersion model. • The combined PEARL-OPS model has been tested against experimental data. • A first conservative tier to assess vapour exposure has been developed. • The sensitivity of the PEARL-OPS model to relevant input parameters is shown. • Proposals are presented for higher tier options for vapour exposure assess- ments. GRAPHICAL ABSTRACT abstract article info Article history: Received 1 July 2016 Received in revised form 25 August 2016 Accepted 26 August 2016 Available online xxxx Agricultural use of plant protection products can result in exposure of bystanders, residents, operators and workers. Within the European Union (EU) FP7 project BROWSE, a tool based on a set of models and scenarios has been developed, aiming to assess the risk of exposure of humans to these products. In the present version of the tool only a first conservative tier is available for outdoor vapour exposure assessment. In the vapour exposure evaluation, the target concentrations in air at 10 m distance from the edge of a treated field are calculated for specific scenarios for each EU regulatory zone. These scenarios have been selected to rep- resent reasonable worst case volatilisation conditions. The exposure assessment is based on a series of weekly ap- plications in a five year period to cover a wide range of meteorological conditions. The volatilisation from the crop is calculated using the PEARL model and this PEARL output provides the emission strength used as input for the short term version of the atmospheric transport model OPS. The combined PEARL-OPS model is tested against measurements from a field experiment. First results of this test show that the mean concentration level was predicted fairly well. However, sometimes the differences between observations and simulations were found to be substantial. Improvements are suggested for the vapour exposure scenarios as well as for further model development. In the current version of the BROWSE tool a simplified procedure is used to assess single and multiple applications. The actual period of application and the time of application during the day are fixed, and the growth stage of the crop cannot be taken into account. Moreover, competing processes such as penetration of the substance into the plant tissue are not considered. The effect of these factors on the target exposure concentrations is discussed. © 2016 Elsevier B.V. All rights reserved. Keywords: Pesticide volatilisation Vapour exposure OPS Modelling Scenario development PEARL Science of the Total Environment 573 (2016) 1010–1020 ⁎ Corresponding author. E-mail address: erik.vandenberg@wur.nl (F. van den Berg). http://dx.doi.org/10.1016/j.scitotenv.2016.08.180 0048-9697/© 2016 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv