Experimental set up to measure the attenuation of airflow by nets in a wind tunnel. A: a fan is placed in a tube with a diameter of 100 mm to direct the airflow. The air flows through a second pipe in which a thermo-anemometer is placed to record the airflow. The airspeed (9, 14, 18, 24, 29, and 36 cm sec-1) is measured at 6 different voltage settings. After recording airspeed in the absence of nets, the airspeed was measured after the airflow was attenuated by nets. B: Findings from wind tunnel experiments. The remaining airflow behind eleven bed nets at six different air speeds (9, 14, 18, 24, 29, and 36 cm sec-1) was measured. The blue bars indicate the mean attenuation in airflow; the error bars indicate the range at the different airspeeds and the red line the average remaining airflow for all 11 bed nets (36%). (Sources of the bed nets: 1, 5, 6 - Philippines; 2 – Thailand; 3, 8 - The Gambia; 4, 7, 10 – Tanzania; 9, 11- Europe).