For each sampling period , two samplers were situated adjacent to the outdoor smoking area , with a third sampler located away from the smoking area as a background sampler in the expected upwind direction .
Photo tip : choose a vantage point upwind from the blowing smoke .
摄影提示:在烟雾吹来的逆风处选择一个有利位置。
If the centerboard is not weighted , like the fiberglass centerboards of many small sailboats , then sailors must keep the boat upright by positioning their own weight on the upwind side of the boat .