Is it safer to be higher or lower on a hillside, if there is radiation in the air?

Under the hill: A nuclear catastrophe is not imminent. The world is not going to end from radiation, heat waves, tornadoes, typhoons, lightening, floods, earthquakes, cold wave or any thing else like that. Have a diet rich in fresh vegetables, fruits, whole grains, low fat milk and milk products, nuts, beans, legumes, lentils and small amounts of lean meats. Avoid saturated fats. Exercise at least 150 minutes/week and increase the intensity of exercise gradually. Do not use tobacco, alcohol, weed or street drugs in any form. Practice safe sex.

Does not matter: If the radiation is in the air it either is there because it is falling from above in which case being sheltered is the safest; or it is admixed with the air in which case it does not matter where on the hillside you might be.

Doesn't matter: Can't hide from Gamma Rays and the prevailing winds. Best place would be in a cave inside of the hill.