Breathing in other people's smoke is potentially harmful to your health. Secondhand smoke contains thousands of chemical, many of which may cause cancer, according to the Office of the Surgeon General. People with asthma or heart conditions, as well as children, the elderly and pregnant women, may be especially vulnerable to the negative effects of secondhand smoke. Signs of secondhand smoke can include physical as well as mental conditions.
Heart Disease
Heart disease claims the lives of some 46,000 nonsmokers who live with smokers each year, according to the American Cancer Society or ACS. People who are exposed to secondhand smoke at home or on the job increase their risk of heart disease by as much as 30 percent, notes the Centers for Disease Control and Prevention.
Breathing secondhand smoke can instantly cause injury to the cardiovascular system and increase the chances of suffering heart attack.
Cancer
An estimate 3,400 lung cancer deaths in nonsmokers is blamed on secondhand smoke annually, reports the ACS. Nonsmokers who are regularly exposed to secondhand smoke increase their risk of lung cancer by approximately 25 percent, notes the CDC.
Research continues into whether there's a connection between secondhand smoke and breast cancer. While animal studies have pointed to a possible link, human studies have drawn mixed conclusions, according to the ACS.
Respiratory Conditions
Signs of secondhand smoke may include breathing difficulties, chest pain and coughing. Between 50,000 and 300,000 cases of bronchitis, pneumonia and other lung infections in children under age 2 are attributed to secondhand smoke every year, according to the ACS.
Breathing secondhand smoke increases the frequency and intensity of asthma attacks in approximately 200,000 to 1 million children annually who have the condition.
Mental Health Problems
British researchers have found that secondhand smoke may be associated with mental health problems. A study published in August 2010 in the online edition of the "Archives of General Psychiatry" determined that extended exposure to secondhand smoke could lead to depression and other psychological conditions. The study collected and analyzed data on some 5,500 nonsmokers and 2,600 smokers who had no previous psychiatric problems. The research was led by Mark Hamer from the Department of Epidemiology and Public Health at University College London.
Nicotine Dependence
A Canadian study published in December 2008 in the journal "Addictive Behaviors" found secondhand smoke exposure at home and in motor vehicles may be linked with nicotine dependence symptoms in children who have never smoked. The research was led by Dr. Jennifer O'Loughlin of the Université de Montréal's Department of Social and Preventive Medicine and a researcher at the Centre Hospitalier de l'Université de Montréal.
