Stopping smoking has numerous health benefits. Within a year of quitting, lung capacity can improve by 10% as coughing lessens and breathing becomes easier. Those who quit by age 30 add 10 years to their life expectancy. Quitting smoking also reduces stress levels, improves senses of taste and smell, and lowers the risk of many cancers and heart or lung diseases. Secondhand smoke increases risks of lung cancer, heart disease, and respiratory illnesses for non-smokers as well. Smoking during pregnancy can cause complications like premature birth and low birthweight for the baby.