And next time you stop to smell the roses, they could be less fragrant.A group of scientists now say pollution is tainting the molecular build-up that causes a flower to smell so sweet.

• 下次你驻足闻玫瑰花味时，它可能没那么香了，科学家们说是因为污染破坏了使花朵闻起来香甜的分子结构。