Answer:
1. Arsenic, benzene, formaldehyde, lead, and mercury are just a few of the more than 70 cancer-causing chemicals in cigarette smoke.
2.They work, for instance, to keep the airways clear of mucus and dirt, allowing us to breathe easily and without irritation. They also help propel sperm.
3.Spirometry measures how much air you can breathe in and out. It also measures how fast you can empty the air out of your lungs. Spirometry helps diagnose breathing problems such as asthma and COPD.
4.
Tar causes cancer of the lungs, mouth and throat.