Oilseed rape is insect-pollinated and has fairly heavy, sticky pollen. You are very unlikely to be affected by the pollen unless you deliberately wade through fields of the stuff, and even then it's more likely to stick to your knickers than get up your nose. The plants are usually grown as a monoculture in blocks of many acres. They will have been treated with all manner of chemicals. The flowers attract pollen beetles, and, if you have a garden next to a field of the stuff, your garden flowers will be ravaged by said beetles once the crop has gone to seed in early summer leaving the beetles feeling a bit peckish. It's horrible stuff, though, admittedly, the oil therefrom is a bit healthier than dripping and lard. I love chips done in dripping and lard, and I hate pollen beetles. And monocultures.