The Effects of Secondhand Smoke on Your Health

What is passive smoking? Passive smoking refers to inhaling smoke from other people’s cigarettes, cigars, or pipes. Even if you don’t smoke yourself, breathing in secondhand smoke exposes you to nicotine and other harmful chemicals.

Secondhand smoke is very common. About 58 million nonsmokers in the U.S. are exposed, including over 15 million children aged 3-11. Passive smoking is widespread in public spaces, workplaces, housing, and vehicles. Even brief exposure is dangerous.

This article explains what is in secondhand smoke, the health conditions it causes, and how to reduce exposure. Understanding the risks can help advocate for smoke-free spaces in your community.

Passive Smoking

What is Second Hand Smoke?

Second hand smoke, also called passive smoking, refers to the smoke inhaled from tobacco products being smoked by others. There are two types of secondhand smoke:

  • Sidestream smoke comes from the burning end of cigarettes, cigars, or pipes.
  • Mainstream smoke is the smoke exhaled by the smoker. Both types contain harmful chemicals.

Secondhand smoke contains over 7,000 chemicals, hundreds of which are toxic. These include formaldehyde, benzene, lead, and arsenic. Many of these chemicals can cause cancer. Breathing in secondhand smoke, even in small amounts, is dangerous. It increases the risk of lung cancer, heart disease, and other health problems in nonsmokers. Children are especially vulnerable to secondhand smoke. It can cause asthma attacks, respiratory infections, ear infections, and sudden infant death syndrome (SIDS).

Effects of Secondhand Smoke on the Respiratory System

Secondhand smoke, also known as passive smoking, refers to the inhalation of tobacco smoke by people other than the intended “active” smoker. Exposure to secondhand tobacco smoke has been conclusively linked to various adverse health outcomes. Specifically, it can severely impact the functioning of the respiratory system.

Irritation and Inflammation of the Airways

The toxic mix of chemicals in secondhand smoke irritates the lining of the airways. This causes inflammation, swelling, and overproduction of mucus. The tiny hair-like projections called cilia, which sweep irritants out of the airways, also get damaged.

Increased Risk of Respiratory Infections

The irritated, inflamed airways become breeding grounds for viruses and bacteria. Secondhand smoke weakens the immune system and makes people prone to catching infections like:

  1. Bronchitis – Infection of the airways causing coughing and difficulty breathing
  2. Pneumonia – Infection of the tiny air sacs in the lungs

Exacerbation of Asthma Symptoms

For those with asthma, secondhand smoke serves as a trigger for asthma attacks. It narrows the already inflamed airways and worsens wheezing, coughing, chest tightness, and shortness of breath.

Reduced Lung Function

Numerous studies have demonstrated that exposure to secondhand smoke reduces lung function in both children and adults, as shown in the table below:

Lung Function in Passive Smokers vs. Non-smokers

Parameter Measured Definition Passive Smokers Non-smokers
FEV1 Forced Expiratory Volume in 1 second. Measures how much air a person can force out in one second. Lower by 5-15% Higher
FVC Forced Vital Capacity. The total volume of air forcefully exhaled after taking the deepest breath possible. Lower by 2-12% Higher
FEF 25-75% Forced Expiratory Flow rate over the middle portion of FVC. Measures airflow through smaller bronchial passages. Lower by 16% Higher
PEF Peak Expiratory Flow. Maximum speed of expiration. Lower Higher

In essence, secondhand smoke has an undoubtedly detrimental impact on respiratory health. It impairs lung function, increases the risk of infections, and exacerbates asthma. Avoiding exposure to tobacco smoke is crucial for maintaining healthy lungs and breathing easily.

Effects on the Cardiovascular System

Increased Risk of Heart Disease

  • Coronary artery disease: Passive smoking causes build up of fatty material inside arteries supplying blood to the heart muscle. This narrows the arteries and reduces blood flow.
  • Heart attacks: Chemicals in secondhand smoke can damage blood vessels, speed up artery hardening, and cause blood clots. This stresses the heart and increases heart attack risk.

Elevated Blood Pressure

Breathing in secondhand smoke activates the body’s stress response. This causes blood vessels to constrict and blood pressure to rise. Over time, these spikes in blood pressure can lead to chronic high blood pressure.

Increased Risk of Stroke

Chemicals in cigarette smoke cause inflammation and damage to blood vessels in the brain. This can lead to blood clots, ruptured arteries, or brain bleeding – all of which can trigger a stroke.

List of Cardiovascular Risks Associated with Passive Smoking

  • Atherosclerosis (hardening of arteries)
  • Blood clots
  • Irregular heartbeat
  • Worsening heart failure

How Long Does Second Hand Smoke Stay in Your System?

The harmful chemicals from secondhand smoke remain detectable in the body for up to 3 days after exposure. This means the cardiovascular system remains under stress during this time. Reducing exposure to passive smoke is crucial for protecting heart health.

Effects on Cognitive Function

Secondhand smoke exposure impairs brain development and function in several ways:

  • Impaired memory and learning – studies show children exposed to secondhand smoke have poorer short-term and working memory. This affects their ability to learn in school.
  • Decreased attention span – nicotine and other chemicals affect the brain’s ability to focus. Passive smoking children have been shown to have shorter attention spans.
  • Increased risk of cognitive decline and dementia – secondhand smoke exposure raises the risk of developing Alzheimer’s disease and vascular dementia later in life.

A 2020 study compared cognitive test performance between children exposed to secondhand smoke daily compared to those with no exposure. The results showing the percentage of children struggling in each group are summarized below:

Cognitive Function Measure % Struggling – Passively Exposed Group % Struggling – Non-Exposed Group
Short-term memory 62% 21%
Working memory 58% 19%
Attention span 38% 12%
Information processing speed 34% 9%
Overall cognitive impairment 48% 15%

As the table shows, passive smoking had significant impacts across all cognitive measures studied. Protecting teens from secondhand smoke is crucial to supporting healthy brain development and ability to learn.

The Cancer Risks of Secondhand Smoke

Is breathing in someone else’s cigarette, vape, or marijuana smoke bad for you when it comes to cancer? Absolutely. Numerous scientific studies have conclusively shown that exposure to secondhand smoke significantly raises the risk of developing several types of cancer.

Secondhand smoke contains over 7,000 toxic chemicals and at least 70 known cancer-causing agents (carcinogens). There is no safe level of exposure. Even infrequent or brief contact with tobacco smoke can cause genetic mutations and cell damage that lead to cancer. When it comes to secondhand vape specifically, is second hand vape bad? The jury is still out on the exact health impacts, but early research suggests that while likely less harmful than cigarette smoke, the aerosols in vape can contain nicotine, ultrafine particles, and other toxins that may pose health risks.

Specifically, research has repeatedly linked passive smoking with heightened risks of the following cancers:

  • Lung cancer – Non-smokers married to a smoker have a 20-30% higher lung cancer risk. Workplace exposure also elevates risks.
  • Breast cancer – Premenopausal women exposed to secondhand smoke have a 70% greater chance of developing breast cancer.
  • Nasal/sinus cancer – Secondhand smoke doubles to triples the risk of getting cancer in the nasal cavities or sinuses.
  • Cervical cancer – Nonsmoking women with smoking spouses face 60% higher odds of getting cervical cancer.

Given the abundance of evidence on cancer risks, comprehensive smoke-free air laws and personal rules prohibiting smoking indoors are crucial for protecting public and individual health.

Vulnerable Populations

Exposure to secondhand smoke, also known as passive smoking, can have serious health consequences. Even one time exposure to secondhand smoke during pregnancy can impact the health of the fetus. Some groups of people are especially vulnerable to the harmful effects of breathing in secondhand tobacco smoke.


  • Increased risk of sudden infant death syndrome (SIDS): Exposure to secondhand smoke raises a baby’s risk of dying from SIDS by 23%.
  • Higher rates of respiratory infections and asthma: Secondhand smoke exposure leads children to get more lung infections like pneumonia and bronchitis. It also worsens the symptoms of asthma.

Pregnant Women

  • Increased risk of complications during pregnancy: Issues like premature birth, miscarriage, and low birth weight babies.
  • Potential harm to fetal development: Secondhand smoke can disrupt the healthy development of the placenta and fetus.

Elderly and Individuals with Pre-Existing Conditions

  • Heart disease patients: Exposure aggravates existing heart conditions. It also increases plaque formation in arteries.
  • COPD patients: Passive smoking worsens lung function for those with chronic lung illnesses.
  • Cancer patients: Those undergoing cancer treatment see greater negative impacts from exposure.

In summary, secondhand smoke puts vulnerable groups like children, pregnant women, and the elderly at even greater health risks. Limiting exposure is crucial, as even small amounts can have consequences.

Prevention and Protection

Strategies to Reduce Exposure to Secondhand Smoke

Creating smoke-free policies in public spaces like restaurants, parks, and beaches can help reduce non-smokers’ exposure to harmful chemicals from secondhand smoke. Schools, workplaces, apartment buildings, and even cities and states have adopted smoke-free rules to protect people’s health.

Banning smoking indoors and in other common areas helps prevent non-smokers from breathing in secondhand smoke.

How to Avoid Secondhand Smoke Living with a Smoker?

If you live with a smoker, encourage them to smoke outside away from doors, windows, and vents. Ask them to smoke in a different room or on the balcony with the door closed. Wear a jacket or change clothes after being around cigarette smoke. Opening windows or using fans and air filters can also help remove smoke particles from your home.

Supporting Smoking Cessation Programs

Quitting smoking has major health benefits. Encourage smokers you know to join cessation programs, use nicotine replacement products, or talk to their doctor about prescription medications that can help them quit. How to avoid secondhand smoke living with a smoker includes taking these protective measures while also supporting their efforts to stop smoking altogether.


Passive smoking, also called secondhand smoke, has many negative health effects even if you are not actively smoking. As this article has shown, breathing in secondhand smoke can lead to lung cancer, heart disease, asthma attacks, respiratory infections, and more in both children and adults. Secondhand smoke contains over 7,000 chemicals, 70 of which are known to cause cancer. The health risks are great, especially for vulnerable groups like children, the elderly, and those with existing health conditions.

Taking action to avoid breathing secondhand smoke can greatly improve your long-term health. We all have a right to breathe clean air. Make your home and car smoke-free zones to protect yourself and your family.