Smoke is made up of tiny solid, liquid and gas particles. All smoke contains carbon monoxide, carbon dioxide, and particulate matter (soot), and often contains a variety of toxic chemicals.
When something is burned, the combustion process is seldom 100% complete. Smoke comes from the incomplete burning of material that contain carbon. The chemicals and amount of particles that are in smoke is determined by what is being burned, what temperature it is being burned at, and how much oxygen is present.
Wildfire Smoke
Smoke from wildfires contains several hundred chemicals including carbon monoxide, volatile organic compounds (VOCs), carbon dioxide, hydrocarbons and nitrogen oxides. The most prevalent pollutant is particulate matter less than 2.5 micrometers in diameter, which is often called PM2.5. Particulates smaller than 2.5 microns pose a large health risk because they are small enough to enter the gas exchange part of the lungs where they can cause long term damage.
Wildfires can also reintroduce radioactive fallout into the air. There are radioactive particulates that have been slowly falling from the upper atmosphere from nuclear weapons testing. The particles that have made their way to the ground can be kicked up into the air again by the heat and disturbance of a wildfire.
Smoke from Burning Fossil Fuels
Common ways of generating electricity are by burning fossil fuels such as coal and oil in power plants. Oil fired power plants produce smoke containing vanadium and nickel. Coal fired power plants produces smoke that contains arsenic, uranium, mercury, aluminum, chromium, selenium, cobalt, copper, iron, and benzene. These elements in smoke are very bad for human health.
Smoke from Automobiles
Gasoline-burning cars emit toxic air pollutants such as benzene, toluene, xylene formaldehyde, acetaldehyde, 1,3-butadiene, acrolein, cadmium, chromium, and lead. Diesel engines emit unburned hydrocarbons, carbon monoxide, NOx, sulfur oxides, particulate matter, black carbon, and VOCs.
Tobacco Smoke
Tobacco smoke is of particular concern. It consists of thousands of chemicals including nicotine, hydrogen cyanide, formaldehyde, lead, arsenic, ammonia, radioactive elements like uranium, benzene, carbon monoxide, nitrosamines, and polycyclic aromatic hydrocarbons. Most of these chemicals are known to cause cancer and heart and lung disease, making tobacco smoke especially concerning. Even if there isn't a smoker in your house, these carcinogenic pollutants can travel easily through the air and linger on clothing.
Health Effects of Smoke
There is the potential for chronic health effects from exposure to smoke. Long term exposure to ambient air containing fine particles has been associated with increases in cardiovascular disease and mortality in populations living in areas with higher fine particulate air pollution. Frequent exposure to smoke for even brief periods may also cause long-term health effects.
Large particles considered ash usually don't travel far from the source, but small particles, or aerosols, can travel huge distances - even across continents. As these pollutants travel through the air they can become more toxic due to reactions with the sun and other chemicals.
To protect against the harm caused by inhaling particulates from smoke, it's important to use a high quality air purifier that can remove these pollutants.