What key factor affecting mortality is significant in the design of protection products?

The significant key factor affecting mortality in the design of protection products is the individual's smoking status. This is due to the clear and well-documented evidence that smoking considerably increases the risk of various health conditions, leading to higher mortality rates. In the context of protection products, such as life insurance, providers assess the risk profiles of applicants to determine appropriate premiums and coverage amounts. Smokers typically face higher premiums, reflecting their increased health risks compared to non-smokers.

While factors like age, gender, and occupational hazards also impact mortality rates, the smoking status is particularly critical because it has a direct and substantial influence on health outcomes. This factor is also often used in underwriting processes, making it essential for the design and pricing of life insurance products.