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Haze Cigarette Equivalent

Enter the PM2.5 reading and the hours you spend outdoors to see roughly how many cigarettes that air equals. This is a rough comparison, not a medical measure.

µg/m³

The 24-hour average PM2.5 in µg/m³ from an air quality site or monitor. It is not the same as the API number.

h

Time spent in that air. Indoors with the windows closed and a purifier on, the exposure is much lower.

Source: Berkeley Earth – Air Pollution and Cigarette Equivalence ↗

This result is an estimate only. Check with your bank or the relevant authority before making decisions.

Live air quality

This is a satellite and model estimate for the chosen city, not a station reading. It can differ from the DOE's official API. The AQI is worked out from the latest hour's PM2.5, not a 24-hour average.

Check the DOE's official API ↗ · Air quality data by Open-Meteo.com(CC BY 4.0)

How it is calculated

  • Cigarettes per day = PM2.5 (µg/m³) ÷ 22
  • Cigarette equivalent for your time = cigarettes per day × hours ÷ 24
  • Hours for one cigarette = 24 ÷ cigarettes per day
  • Hours for a pack = hours for one cigarette × 20

The 22 µg/m³ figure is the Berkeley Earth rule of thumb. To check the API category, use the haze API checker. To plan clean air at home, see the air purifier size calculator.

Worked example

PM2.5 of 100 µg/m³ for 8 hours outdoors:

  • Cigarettes per day: 100 ÷ 22 = 4.5
  • For 8 hours: 4.5 × 8 ÷ 24 = 1.5 cigarettes
  • One cigarette takes 24 ÷ 4.5 = 5.3 hours, and a pack takes 106 hours

Why your number may differ

This is a rough comparison from one rule of thumb. PM2.5 changes through the day, and the number you enter should be an average for the time you are outside. A fitted N95-type mask or being indoors lowers what you breathe in. Haze and tobacco smoke are different, so the health effects are not the same. This is not medical advice; ask your doctor if you have a breathing or heart condition.

Frequently asked questions

How does PM2.5 convert to cigarettes?

Berkeley Earth estimated that breathing 22 µg/m³ of PM2.5 for 24 hours is about the same as smoking one cigarette. Cigarettes = PM2.5 ÷ 22 × hours ÷ 24.

Is this exact?

No. It is a rule of thumb for making air pollution easier to picture. Tobacco smoke and haze are different mixtures, and the effect depends on age, health and how much you breathe.

Is the API the same as PM2.5?

No. The API is an index that takes the worst of several pollutants. Use the PM2.5 reading in µg/m³ for this calculator, and the haze API checker for the API category.

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