Outdoor Wind Tunnel Test

During risk assessment and EU approval of active substances, air transport and deposition of plant protection products (PPP) needs to be considered. Outdoor wind tunnel testing can be conducted to generate necessary data on volatilisation and deposition of PPP to non-target areas.

In the past, we have collaborated with RLP AgroScience GmbH, Neustadt, Germany, to conduct such studies. Recently, we have established the infrastructure in our own testing facility and we carry out such studies also under GLP.

Wind tunnel test system

Outdoor wind tunnel trials are semi-field experiments excluding environmental parameters like natural rainfall or changing wind speed and wind direction as a basic requirement to investigate volatilization and subsequent deposition under controlled but realistic outdoor conditions. A fan unit at one end of the wind tunnel produces a constant wind speed over the target and non-target areas. The target area behind the wind engine has a width of 4 m and a length of 25 m resulting in a target area of 100 m². On the non-target area, i.e., behind the treated area, sampling points were located at defined downwind distances of up to 20 m from the target area to assess the short range transport of PPP. Since the wind tunnel test system at Fraunhofer IME is 70 m long, it is possible to investigate the volatilization and deposition for downwind distances > 20 m and, hence, cover additionally the long range transport of PPP.

The wind tunnel test set up is suitable to carry out GLP studies according to Publication 1 and 2 (see below) but also for multi-purpose experimental “Higher Tier” investigations of non-target exposition of PPP via air (e.g. spray drift, vapour drift).

In addition, a laboratory volatisation chamber is available at Fraunhofer IME facilitating extensive pretesting under controlled laboratory conditions.