WFTF comprehensive rules (see exert below) already prohibit the use of powders, using your cigarette smoke, throwing leaves/grass/soil etc from being used. Dont shoot the messenger.
In SA, SAFTAA have implemented these changes for league shoots so that our shooters are in-line with the WFTF.
from WFTF Comprehensive rules
Wind reading options
To assist shooters reading the wind the available options are :
Wind indicator (string or similar) attached to the rifle.
No additional equipment, electrontic or other, may be used to assist the shooter in evaluating the wind or other weather conditions.