Pollen represents a critical stage in the life cycle of plants, as viable pollen is crucial for efficient sexual plant reproduction. However, pollen may also be a vector for transgene escape from genetically modified crops. To investigate the possible contribution pollen viability may play in determining transgene escape, the project described in this report had two objectives: to review the available literature on pollen viability and the effect of environmental factors on it, and to analyze the viability of pollen of various species in the environment.