95% Confidence Interval (CI) is a range of values (upper and lower) that you can be 95% certain contains the true mean of the population.

The relative risk is a comparison of the risk of getting lung cancer for those exposed to diesel exhaust compared to those who have never been exposed to diesel exhaust – for example, if the relative risk is 1.5, it means that for the cumulative diesel exhaust exposure entered into the calculator, the risk associated with that exposure is 1.5 times higher than the background risk of lung cancer for those who have not been occupationally exposed to diesel exhaust.