Author: Daniel Martins Figueiredo (d.m.figueiredo@uu.nl)
Last update: 05/02/2026
To estimate the airborne pesticide concentrations at a national scale, it is crucial to assess both the initial spray drift (i.e. pesticide that moves outside the area of application) and subsequent volatilization of active substances (AS) following application. The proportion of AS entering the atmosphere depends on factors such as application method, meteorological conditions, and crop canopy characteristics.
First, each agricultural field (polygon) is assigned an AS mass based on crop type and pesticide application data. Second, each individual field is paired to the closest meteorological station. Next, pesticide dispersion in the air is modeled using a short-range Gaussian plume approach, similar to Lebeau et al. (2011). Volatilization from soil and plants follows the same equations as the PEARL model (Van den Berg et al. 2016). The dispersion model incorporates real-world meteorological data, including wind speed, humidity, and atmospheric stability, to simulate the spread of pesticides in the air.
For each country, different simulations were made to test usability of the modelling framework, computational efficiency, and uncertainty in model output. Moreover, this approach shows that to produce air concentration maps there are different ways the model can be ran, and depending on the setting the output can become different:
For the Netherlands, simulations were made multiple times to account for variability within periods when farmers could have applied a pesticide. The output is an average value at 10meters downwind from each field and then all values were averaged in a 1kmx1km grid resolution. Here, meteorological conditions were set (based on expert input) for: No rain fall during spraying; temperatures above 5 and below 28 degrees Celsius; Relative humidity above 40%; Wind speed below 5 meters per second.
For Czech Republic, given the smaller number of agricultural plots per km2, air concentrations were estimated at 50meters distance around the centroid of each field for the 8 most predominant wind directions and assuming a low droplet size class of 30 μm. The output is an average value from all fields for each 2.5kmx2.5km grid resolution.
For Denmark, air concentrations were estimated similarly as for Czech Republic. The output is an average value from all fields for each 1kmx1km grid resolution.
Important to note that only downward spraying was included in this simulation.
References:
- Figueiredo, D. M., Duyzer, J., Huss, A., Krop, E. J., Gerritsen-Ebben, M., Gooijer, Y., Vermeulen, R. C., 2021. Spatio-temporal variation of outdoor and indoor pesticide air concentrations in homes near agricultural fields. Atmospheric Environment, 262, 118612. https://doi.org/10.1016/j.atmosenv.2021.118612.
- Lebeau, F., Verstraete, A., Stainier, C., Destain, M. 2011. RTDrift: A real time model for estimating spray drift from ground applications. Computers and Electronics in Agriculture, 77(2), 161-174. https://doi.org/10.1016/j.compag.2011.04.00
- van den Berg, F., Tiktak, A., Boesten, J.J.T.I., van der Linden, A.M.A. 2016. PEARL model for pesticide behaviour and emissions in soil-plant systems; Description of processes. The Statutory Research Tasks Unit for Nature & the Environment (WOT Natuur & Milieu). WOt-technical report 61. https://edepot.wur.nl/377664.
Summary for General Public
Background
Pesticides are widely used in agriculture, and small amounts can enter the air during and after spraying. People living or working near fields may therefore be exposed through breathing the surrounding air. However, measuring pesticides everywhere is not feasible, so scientists use models to estimate where concentrations could occur.
How it works
This tool shows where pesticide concentrations in outdoor air may be higher or lower, based on scientific calculations, and helps to better understand potential inhalation exposure in agricultural areas. The tool combines information on crop types, pesticide use, weather conditions, and wind patterns to estimate how pesticides may spread in the air after being applied. These estimates are shown on maps as average concentrations over grid areas rather than exact locations.
What it offers
- A visual overview of where airborne pesticide concentrations could be higher
- A tool to raise awareness about environmental exposure pathways
- A way to explore large-scale patterns, rather than individual events
Limitations / Disclaimer
- The values shown are calculated estimates, not measurements
- The maps do not show real-time or constant air pollution
- Seeing a location on the map does not mean that concentration always occurs there
- Important: The tool does not assess health risk or safety levels
Summary for Policy makers
Background
Understanding potential human exposure to pesticides beyond food intake is increasingly important for environmental health policy. Inhalation exposure from agricultural use is difficult to monitor systematically, yet relevant for land-use planning, occupational health, and population-level assessments.
How it works
This tool supports evidence-based policy by identifying areas where airborne pesticide concentrations may be higher, helping to prioritize monitoring, guide preventive measures, and inform discussions on agricultural and environmental policy. Using agricultural activity data, pesticide application assumptions, and real meteorological conditions, the tool models how pesticides may enter and disperse in ambient air. Results are presented as national-scale maps showing average estimated concentrations across grid cells, allowing comparison of spatial patterns within countries.
What it offers
- A screening-level overview of potential airborne pesticide exposure
- Support for prioritizing regions for monitoring or further assessment
- Evidence to inform preventive, zoning, or mitigation strategies
- A transparent basis for cross-sector dialogue between agriculture, health, and environment
- Inputs for impact assessments and long-term policy evaluation
Limitations / Disclaimer
- Outputs are not measurements and cannot be used to enforce compliance
- Maps do not indicate health risk or regulatory exceedances
- Differences between countries reflect both real conditions and modelling choices
- Results should be interpreted as supporting evidence, not stand-alone conclusions
Description for Scientists
Background
Assessment of pesticide exposure via inhalation requires a realistic representation of spray drift and post-application volatilization under agricultural conditions. Due to limited monitoring data at national scales, modelling approaches are essential to generate harmonized exposure inputs.
How it works
This tool provides spatially explicit, model-based estimates of airborne pesticide concentrations to support inhalation exposure assessment, methodological comparison, and exploratory epidemiological analyses. Active substance application is assigned at field level based on crop and pesticide use data. Each field is linked to nearby meteorological stations, and atmospheric dispersion is simulated using short-range Gaussian plume modelling. Volatilization from soil and crops follows PEARL-based formulations. Country-specific implementations reflect differences in land use density, grid resolution, meteorological sampling, and scenario design.
What it offers
- National-scale air concentration estimates for selected pesticides
- Harmonized spatial outputs suitable for screening-level inhalation exposure assessment
- Inputs for linkage with health, environmental, or modelling studies
- Insight into uncertainty and sensitivity related to modelling choices