Cigarette Tar Testing Conditions: Standards, Parameters, and Laboratory Procedures

Cigarette tar testing conditions define the standardized laboratory parameters under which total particulate matter, water, and nicotine in mainstream smoke are captured and quantified to calculate tar yield per cigarette. These conditions, governed by ISO 4387, ISO 3308, ISO 3402 and their Chinese national equivalents such as GB/T 19609, cover every stage of the determination, from sample conditioning to machine smoking and chromatographic analysis. This article explains the complete technical framework applied by accredited third-party laboratories and tobacco manufacturers to obtain reproducible, internationally comparable tar results.

Technical Overview

In cigarette smoke chemistry, "tar" is the regulated term for nicotine-free dry particulate matter (NFDPM). It is obtained by smoking cigarettes on a routine analytical smoking machine under strictly specified conditions, collecting the particulate phase of mainstream smoke on a glass-fiber Cambridge filter pad, and then subtracting the water and nicotine contained in that condensate from the total particulate matter (TPM). Because tar yield has no meaning unless smoke generation is fully standardized, the entire determination is controlled by a family of international and national standards.

The core method is defined by ISO 4387, "Cigarettes — Determination of total and nicotine-free dry particulate matter using a routine analytical smoking machine," which corresponds to the Chinese national standard GB/T 19609. Supporting standards complete the framework: ISO 3308 defines the smoking machine and standard smoking conditions, ISO 8243 covers cigarette sampling, ISO 3402 specifies the conditioning atmosphere, ISO 10315 covers nicotine determination by gas chromatography, ISO 10362-1 and ISO 10362-2 cover water determination, and ISO 8454 (corresponding to GB/T 23355) covers carbon monoxide in the vapor phase.

Results are expressed in milligrams per cigarette, normally rounded to 0.1 mg. Machine-measured tar yields are used worldwide for regulatory compliance and mandatory pack labeling; many jurisdictions, including the European Union and China, enforce a maximum tar ceiling of 10 mg per cigarette for products placed on the market.

Testing Samples

Filter Cigarettes

Finished filter-tipped cigarettes are the most frequently tested sample type, covering king-size, standard, slim and super-slim formats. Samples may be drawn from retail packaging for compliance verification or from production lines for in-process quality control. Filter ventilation, tipping paper length and rod circumference are recorded because they directly influence smoke delivery.

Plain (Non-Filter) Cigarettes

Plain cigarettes are tested under the same analytical framework, with an adjusted butt length specification. Although less common in many markets, they remain relevant for export certification, legacy brand evaluation and research programs.

Sampling and Pre-Test Screening

Sampling is performed according to ISO 8243 to ensure statistical representativeness of the lot. Before smoking, individual cigarettes are marked and measured for mass, length, circumference and draw resistance; outliers falling outside the limits set by the sampling plan are excluded so that physical variability does not bias the smoke chemistry results.

Testing Items

A standard machine-smoking determination under ISO 4387 / GB/T 19609 yields the following reported items:

• Total particulate matter (TPM), mg per cigarette, determined gravimetrically on the Cambridge filter pad.
• Water in the smoke condensate, mg per cigarette, determined by gas chromatography (ISO 10362-1) or Karl Fischer titration (ISO 10362-2).
• Nicotine in the smoke condensate, mg per cigarette, determined by gas chromatography with flame ionization detection (ISO 10315).
• Tar, i.e., nicotine-free dry particulate matter (NFDPM), mg per cigarette, obtained by calculation: Tar = TPM − water − nicotine.
• Carbon monoxide in the vapor phase, mg per cigarette, measured by non-dispersive infrared analysis (ISO 8454 / GB/T 23355), which is commonly reported together with tar and nicotine for labeling.
• Average puff count per cigarette, reported to one decimal place.

Testing Methods

Conditioning Atmosphere

Prior to smoking, cigarettes and Cambridge filter pads are conditioned in the standard atmosphere specified by ISO 3402: a temperature of 22 °C ± 2 °C, a relative humidity of 60 % ± 5 %, and an atmospheric pressure between 96 kPa and 103 kPa. Cigarettes are conditioned for a minimum of 48 hours so that moisture equilibrium is reached; the smoking room itself is maintained at the same atmosphere to prevent drift during the run.

Standard ISO Smoking Conditions

Each cigarette is mounted in the smoking machine and smoked to a prescribed butt length under the following baseline parameters defined in ISO 3308:

• Puff volume: 35 mL per puff, verified with a calibrated volume-measuring device.
• Puff duration: 2.0 seconds.
• Puff frequency: one puff every 60 seconds.
• Puff profile: bell-shaped flow-time curve.
• Filter ventilation: not blocked or occluded in any way.
• Butt length: the tipping-paper (overwrap) length plus 20 mm for filter cigarettes, subject to the maximum specified by the standard (35 mm), and 23 mm for plain cigarettes.
• Sample size: a minimum of 20 cigarettes per determination, with at least 5 cigarettes per smoking port on multi-channel machines.

Smoking is terminated at the specified butt length, and the butt is extinguished without further puffs. Cigarettes that do not burn uniformly or whose pressure-drop behavior falls outside machine acceptance limits are rejected and replaced.

Gravimetric and Chromatographic Determination

Each pre-conditioned, pre-weighed 44 mm glass-fiber Cambridge filter pad captures the particulate phase of mainstream smoke from its assigned cigarettes. After smoking, the pad is re-weighed on an analytical balance to determine TPM by mass gain. The pad is then extracted with a measured volume of propan-2-ol containing internal standards. Nicotine in the extract is quantified by gas chromatography with flame ionization detection per ISO 10315, and water is quantified by gas chromatography per ISO 10362-1 or, alternatively, by Karl Fischer titration per ISO 10362-2. The vapor phase passing through the pad is collected in a gas bag for carbon monoxide measurement by non-dispersive infrared spectroscopy per ISO 8454.

Intense Smoking Regimens

For exposure-oriented characterization, laboratories may apply alternative intense regimens. The internationally recognized intense regimen uses a 55 mL puff volume, a 2.0 second puff duration, a 30 second puff interval and 100 % blocking of filter ventilation holes. An intermediate regimen (45 mL puff volume, 30 second interval, 50 % ventilation blocking) is also used in some jurisdictions. Intense data are intended for research and product comparison rather than pack labeling, and they consistently produce higher deliveries than the ISO baseline.

Calibration and Quality Control

Quality assurance measures include verification of puff volume, puff duration and puff frequency against ISO 3308 tolerances, leak testing of the smoke path, use of pad blanks, replicate determinations, and regular testing of certified monitor test pieces conforming to ISO 16055 to confirm machine performance. Precision is judged against the repeatability (r) and reproducibility (R) limits published in ISO 4387, which were established through interlaboratory studies conducted in accordance with ISO 5725.

Applications

Cigarette tar testing under standardized conditions supports a wide range of industrial and regulatory purposes:

• Regulatory compliance and verification of statutory tar ceilings in markets that limit machine-measured yields.
• Mandatory labeling of tar, nicotine and carbon monoxide values on cigarette packs.
• Manufacturing quality control and statistical trending of smoke deliveries across production batches.
• Product research and development, including evaluation of blend composition, filter design, ventilation levels and paper permeability on delivery.
• Benchmarking of new or redesigned products against reference products and historical data.
• Scientific research into smoke chemistry and comparative product characterization under both ISO and intense regimens.

FAQ

What exactly is "tar" in cigarette testing?

Tar is the nicotine-free dry particulate matter (NFDPM) in mainstream smoke. It is calculated by subtracting the water and nicotine content of the smoke condensate from the total particulate matter collected on a Cambridge filter pad, and it is reported in milligrams per cigarette.

What are the standard ISO smoking conditions for tar testing?

The standard conditions are a 35 mL puff volume, a 2.0 second puff duration, one puff every 60 seconds, a bell-shaped puff profile, unblocked filter ventilation, and smoking to a prescribed butt length. Samples must first be conditioned for at least 48 hours at 22 °C ± 2 °C and 60 % ± 5 % relative humidity per ISO 3402.

How is tar different from TPM?

TPM (total particulate matter) is everything retained by the filter pad, including water and nicotine. Tar is TPM corrected for these two components, which is why water and nicotine determinations are always performed alongside the gravimetric TPM measurement.

Why do intense smoking regimens give higher tar values?

Intense regimens use a larger puff volume (55 mL), a shorter puff interval (30 seconds) and complete blocking of filter ventilation. Together these parameters draw more smoke from each cigarette, so tar, nicotine and carbon monoxide deliveries are substantially higher than under the ISO baseline.

How many cigarettes are required for one determination?

ISO 4387 requires a minimum of 20 cigarettes per determination, distributed so that each smoking port handles at least 5 cigarettes, ensuring the filter pad collects a measurable and representative mass of condensate while avoiding pad overload.

Which standards apply in China?

The Chinese national standard GB/T 19609 is technically equivalent to ISO 4387 and governs tar determination, while GB/T 23355 corresponds to ISO 8454 for carbon monoxide. Testing is carried out either by accredited third-party laboratories or by in-house facilities using equipment and procedures aligned with the ISO framework.