A recent Harvard study estimated that fossil fuel emissions caused 8 million deaths in 2018. That means pollution from burning fossil fuels was responsible for almost 20% of all deaths that year. It is difficult to estimate the total worldwide health burden of air pollution, but many scholars agree that between 5 to 9 million people die from air pollution each year.
Those numbers are striking, but emissions are not the only air quality threat with a significant impact on public health. The World Health Organization (WHO) estimates the total number of tobacco-related deaths to be around 7 million each year — about the same number as the deaths caused by air pollution.
These numbers may make it seem like air pollution and smoking are equally dangerous, but that is not exactly true. Air pollution — and tobacco use, for that matter — is not distributed equally around the world. In most places, outdoor air quality rarely gets bad enough to mimic the effects of a smoking habit.
For example, in the United States, tobacco smoke is responsible for almost half a million deaths every year, but air pollution is only responsible for about 60,000. This is likely because air pollution in the U.S. is typically too low to cause as many health issues as cigarette smoke.
Read on for more on how air pollution and tobacco smoke differ, how they are alike, and why that comparison may not be as helpful as it seems.
What is the difference between air pollution and tobacco smoke?
Air pollution is a broad term that describes anything that can decrease air quality, either indoors or outdoors. It includes sources such as vehicle exhaust, wildfires and, yes, tobacco smoke. While smoke from cigarettes can contain many of the same chemicals as the smog you would find polluting the air of a busy city, it also has additional pollutants that lead to added potential health effects.
Key Components of Air Pollution
Thanks to the Clean Air Act, the Environmental Protection Agency (EPA) established a set of air quality standards to help the general public understand and lower their exposure to outdoor air pollution. These standards are known as the National Ambient Air Quality Standards (NAAQS), and they outline most of the main components of outdoor air pollution.
Particulate matter: Tiny airborne particles, called particulate matter (PM), are a significant air quality concern. Often too small to be seen by the naked eye, PM can be made of a wide range of solids and liquids, including metals, organic compounds, biological material, carbon, sulfates, nitrates, and other minerals.
The two main categories of PM are PM10 and PM2.5. PM10 consists of coarse particles smaller than 10 microns, and PM2.5 are fine particles smaller than 2.5 microns. PM2.5 particles are small enough to penetrate deep into the lungs when inhaled, making them arguably the most dangerous type of pollution. Some may even enter the blood, where they can spread to other areas of the body.
Volatile organic compounds: This group of carbon-containing gaseous pollutants, sometimes referred to as simply hydrocarbons, includes a wide variety of different chemicals. Volatile organic compounds (VOCs) can be naturally occurring or human-made. Common outdoor sources of VOCs include oil and gas industry emissions and vehicle exhaust. Indoors, VOCs can come from manufactured furniture, textiles, cleaning products, paints and even building materials.
Ozone: Ozone naturally occurs in the stratosphere, but it can also be created at the ground level by reactions between different types of air pollution, such as organic compounds and nitrogen oxides. Once created, ozone can react with other substances in the air to form even more air pollution. The products of ozone and other atmospheric chemicals are called secondary organic aerosols.
Nitrogen oxides: Nitrogen oxides, such as nitrogen dioxide (NO2), are highly reactive gases formed by the burning of fossil fuels. Key sources of NO2 pollution include emissions from cars, buses, trucks, off-road equipment and power plants. NO2 can also react with other airborne chemicals to create both PM and ozone.
Carbon monoxide: Like NO2, carbon monoxide (CO) is a product of combustion, meaning it is released when something is burned. Common sources of CO include vehicle emissions, gas stoves and other activities that burn fossil fuels. CO gas is both colorless and odorless, and it can be harmful when inhaled.
Sulfur oxides: Sulfur dioxide (SO2) is the most concerning member of the sulfur oxide family. It is created through the burning of fossil fuels, especially by power plants and other industrial facilities. Ships, trains and other vehicles can also emit SO2 if they burn coal or other fuel with a high sulfur content.
Key Components of Tobacco Smoke
Cigarette smoke is made up of a complex mixture of over 7,000 chemical compounds, many of which are also found in other sources of air pollution. Smoke is a product of combustion, and it contains gaseous chemicals, liquid aerosols, and particulate matter (including PM2.5).
Hundreds of the chemicals in cigarette smoke are toxic, and over 70 can cause cancer. A few of the most harmful components of tobacco smoke include:
- 1,3-butadiene: A known carcinogen and the most significant cancer risk in cigarette smoke.
- Acrolein and acetaldehyde: Chemicals with the greatest potential to irritate the respiratory tract.
- Cyanide, arsenic, and cresols: Chemicals with the most significant potential to harm cardiovascular health.
Other harmful chemicals found in cigarette smoke include carbon monoxide, formaldehyde, benzene, hydrogen cyanide, nitrous oxides and polycyclic aromatic hydrocarbons (PAHs). The wide range of pollutants present in cigarette smoke can lead to multiple, varied effects on human health, such as cancer, lung disease, heart disease, stroke, and reduced fertility.
The effects of breathing in cigarette smoke are not only felt by smokers. There is no safe level of smoke exposure, and secondhand and even thirdhand smoke may be a threat to health. (Secondhand smoke includes the smoke that comes from the end of a burning cigarette and the smoke exhaled by the smoker. Thirdhand smoke is the residue of secondhand smoke that accumulates on indoor surfaces over time.)
When does air pollution get worse than smoking?
When comparing the effects of cigarette smoke and other types of air pollution, there are two main things to consider: the types of pollutants present in the air and their concentrations. For one source of pollution to be worse, it should contain a more harmful mixture of pollutants, stronger concentrations of harmful pollutants, or both.
The Berkeley Earth organization has created a formula to help people look at air pollution in a unique way. It lets you compare the air pollution in a given city to the level of pollutants you would be exposed to from a cigarette. For example, they calculate that, on an average day, people in the U.S. breathe in about as much air pollution as you would get from smoking just under half a cigarette.
Berkeley researchers decided on this conversion rate by comparing the total death burden of cigarettes to the total death burden of exposure to PM2.5 pollution. According to their calculations, inhaling 22 micrograms of PM2.5 per cubic meter for 24 hours gives you the same pollution exposure as smoking one cigarette.
If you go to the EPA Air Quality Index (AQI) website, you can plug in these numbers to get an AQI value of 72, a moderate or yellow level. The EPA classifies air quality at this level as acceptable but not without health risks, especially for those sensitive to air pollution.
The Centers for Disease Control and Prevention (CDC) estimates that people who smoke usually smoke an average of 14 cigarettes each day. Using Berkeley Health’s formula, we can translate this to around 308 micrograms of PM2.5 per cubic meter, which gives us an AQI value of 358.
This means that for air pollution to be as harmful as smoking 14 cigarettes a day, the AQI in a region must be above 358.
This number is practically off the EPA’s air quality chart — any number over 150 is considered unhealthy — and it indicates an air quality health warning of emergency conditions. Everyone is likely to be affected by air pollution at this level.
So, how often does air quality reach AQI ratings of 358 or above? It depends on where you live. In most places, this level of air pollution would usually be associated with a major air quality event, such as a wildfire. Some cities, such as Kolkata, India, are more likely to experience days where the AQI nears or exceeds 300.
Looking forward: Air Pollution and Smoking
Comparing air pollution to smoking can be an interesting way to wrap your head around the potential harm caused by exposure to poor air quality. However, it is important to remember that breathing in polluted air and smoking are not the same thing. The idea that they are can lead people to underestimate the danger that cigarette smoke poses to human health.
Smoking causes more disability and premature deaths than air pollution, all of which are completely avoidable. Additionally, medical problems caused by smoking tend to arise at a younger age than health issues from exposure to air pollution.
Air pollution is still a major public health issue, though, especially in the developing world. While levels of air pollution in rich countries have fallen over the past couple of decades, most countries’ populations are still consistently exposed to levels of air pollution that exceed the guidelines set by the World Health Organization (WHO).
Tobacco also has a more significant negative impact on the public health of poorer countries. Over 80% of the 1.3 billion tobacco users in the world live in low- and middle-income countries. Those numbers will be difficult to overcome, as tobacco use remains more resistant to change than outdoor air pollution.
While some media outlets and researchers may refer to air pollution as “the new smoking,” the “old smoking” has not gone anywhere. No matter how poor the air quality is in a given region, smoking is always harmful to the smoker and everyone exposed to second- and thirdhand smoke. Air pollution is a serious concern, but so is tobacco use, and both should be considered when working to improve public health.