// tool 04 · air quality in cigarettes
AQI to Cigarettes
A microgram figure is hard to feel. A cigarette count isn't. Enter an AQI or a PM2.5 reading and see how many cigarettes a day the fine-particle dose is roughly equal to, using the widely cited 22 µg/m³ ≈ one cigarette rule of thumb.
24-hour exposure at this level.
// dose analogy for PM2.5 mass only · ~22 µg/m³ over 24h ≈ one cigarette
What the cigarette number really means
Fine particulate matter, PM2.5, is the pollutant that does the most damage to human lungs, and it is exactly what cigarette smoke is loaded with. That shared ingredient is what makes the comparison possible: you can line up the mass of particles you inhale from a day of city air against the mass you would inhale from a cigarette.
The comparison is a dose analogy for particles only. It captures how much PM2.5 reaches your lungs, and nothing else. Tobacco smoke carries nicotine, tar and a long list of chemicals that ambient air does not, so a hazy afternoon is not chemically the same as lighting up. What the number does well is turn "PM2.5 is 88 µg/m³" into something your body understands: four cigarettes.
How it works
The equivalence itself is simple division. Take the PM2.5 concentration in µg/m³ and divide by the per-cigarette figure:
If you give the calculator a US AQI instead of a raw concentration, there is one step first. AQI is not proportional to PM2.5, it is a piecewise scale, so we run the EPA's 2024 breakpoint curve backwards to recover the concentration the AQI came from, then divide. Feeding PM2.5 in directly is the most accurate route.
Note: the 22 µg/m³-per-cigarette figure is an approximation of the PM2.5 dose, not a medical equivalence. It says nothing about nicotine, addiction, or the many non-particle harms of smoking.
Frequently asked questions
How many cigarettes is the air quality where I am?+
Enter your current AQI or PM2.5 reading above. The rule of thumb, published by Berkeley Earth, is that breathing air at about 22 µg/m³ of PM2.5 for 24 hours delivers roughly the same fine-particle dose as smoking one cigarette. So a PM2.5 of 110 µg/m³ is about five cigarettes a day, and an AQI of 150 (roughly 55 µg/m³) is about two and a half.
Is polluted air really the same as smoking cigarettes?+
Only for one specific thing: the mass of fine particles (PM2.5) your lungs take in. Cigarette smoke also contains nicotine, tar and hundreds of other chemicals that outdoor air does not, and smoking delivers its dose in concentrated bursts. The cigarette number is a way to make an abstract microgram figure feel real, not a claim that a smoggy day is chemically identical to smoking.
Where does the 22 µg/m³ per cigarette figure come from?+
From Berkeley Earth physicist Richard Muller's analysis, which compared the PM2.5 dose from cigarettes to ambient air pollution. One cigarette raises a person's 24-hour average PM2.5 intake by roughly the amount you would get from a full day at 22 µg/m³. It is an approximation, but it is the most widely cited one.
Does the calculator use AQI or PM2.5?+
Either. The cigarette equivalence is fundamentally about PM2.5 mass, so if you enter a US AQI value we first convert it back to a PM2.5 concentration using the EPA's 2024 breakpoints, then apply the equivalence. Entering PM2.5 directly skips that step and is the most precise input.
Why does the same AQI give a different cigarette count on other sites?+
Because AQI is not a linear measure of PM2.5, and different tools convert it differently, or use a slightly different µg/m³-per-cigarette figure. We invert the official EPA piecewise curve and use 22 µg/m³ per cigarette. If another calculator assumes, say, a flat conversion or a different constant, its numbers will drift from ours, especially at high AQI.
Sources
Count the cigarettes in your own air.
City averages hide what you actually breathe indoors, while cooking, or on your commute. Partycle reads the real PM2.5 around you, so the number is yours, not a forecast for the whole city.