i40

L T Kozlowski, R J O’Connor.............................................................................................................................

Tobacco Control 2002;11(Suppl I):i40–i50

See end of article forauthors’ affiliations.......................
Correspondence to:
Lynn T Kozlowski, PhD,
Department of
Biobehavioral Health, The
Pennsylvania State
University, 315 East
Henderson Building,
University Park, PA 16802,
USA; ltk1@psu.edu.......................

R

Objective: To review tobacco industry documents on filter ventilation in light of published studies andto explore the role of filter ventilation in the design of cigarettes that deliver higher smoke yields tosmokers than would be expected from standard machine smoked tests (Federal Trade Commission(FTC), International Organization for Standardization (ISO)).
Data sources: Searched from November 1999 to November 2000 internet databases of industry
documents (www.pmdocs.com, www.rjrtdocs.com, www.lorillarddocs.com, www.bw.aalatg.com,
www.cdc.gov/tobacco/industrydocs, www.tobaccodocuments.org, www.tobaccopapers.org, www.
hlth.gov.bc.ca/Guildford, www.cctc.ca/ncth/Guildford, www.cctc.ca/ncth/Guildford2) for documents related to filter ventilation. Documents found dated from 1955 through 1994.
Study selection: Those documents judged to contain the most relevant information or data on filter
ventilation related to cigarette taste and compensatory smoking, while also trying to avoid redundancy
from various documents deriving from the same underlying data.
Data synthesis: Filter ventilation is a crucial design feature creating three main problems for lower tar
cigarettes as measured by official smoking machine testing. Firstly, it misleadingly makes cigarettes
taste lighter and milder, and, therefore, they appear less dangerous to smokers. Secondly, it promotes
compensation mainly by facilitating the taking of larger puffs. Thirdly, for very heavily ventilated cigarettes (that is, > 65% filter air dilution), behavioural blocking of vents with lips or fingers is an additional
contributor to compensatory smoking. These three effects are found in industry research as well as published research.
Conclusions: Filter ventilation is a dangerous, defective technology that should be abandoned in lesshazardous nicotine delivery systems. Health interested groups should test cigarettes in a way thatreflects compensatory smoking. Lower tar (vented filter) cigarettes should be actively countermarketed.

ecently disclosed documents of the tobacco industry givea view of what the industry knew and when they knew it.
This review examines the industry’s secret reports on
cigarette design alongside published scientific literature.
Previous reports1–5 using industry documents6–8 have discussed
in broad terms the design of “elastic” cigarettes that promote“compensation” (the attainment of higher smoke exposuresby human smokers of lower tar cigarettes than by standard
smoking machines). A summary of compensatory behaviours
that can be used per cigarette is shown in the box below. Of
course, smoking more cigarettes per day is another form ofcompensation. This review explores in greater detail how filter
ventilation works to make the modern, compensatable
cigarette. Our review is not exhaustive. While we were searching the web sites, the contents kept increasing. We do notknow when or if they will be complete. We also do not provide
a complete review of the documents we found. The literature
is very large and often highly redundant. A complete review
would require many pages of analysis and be tedious to read.
Instead, we offer an analysis of the most informative
documents.
When health concerns related to smoking were first raised in
the 1950s, cigarette manufacturers responded by introducing
filtered cigarettes and began what came to be called the “Tar
Derby”. Manufacturers competed with one another to reassure
health conscious smokers with new, “healthier” products.9 By
the early 1960s in the USA, some health groups expressed concern that these health claims were not backed by objective scientific data. In 1967, the Federal Trade Commission (FTC) in
the USA began a programme to test cigarettes for tar and nicotine yields in cigarette smoke.10 The test procedure was essentially the same as developed by researchers at a major US cigarette manufacturer11; a machine takes a 35 ml puff of two
seconds duration once a minute until a fixed butt length iswww.tobaccocontrol.com

Ways to increase smoke intake from each cigaretteA. Increase total volume of smoke per taken per cigarette– (1) Take larger puffs– (2) Take more puffs– a. smoke to a shorter butt length– b. puff more frequently
B. Increase concentration of smoke per puff
– (1) Block vents on heavily vented cigarettes (> 65% air
dilution) with lips, fingers, or tape– (2) Increase puff velocity (lowering filter effectiveness)– (3) Remove filtersreached (23 mm or overwrap plus 3 mm).10 The International
Organization for Standardization (ISO) adopted the same
parameters in the 1980s, with slight modification (the fixed
butt length was defined as FTC, with an additional criterion offilter plus 8 mm).12 Standard cigarette testing is now conductedin the USA, UK, Australia, Japan, and other countries.13 14 The
official smoking machine tests for smoke yields (tar, nicotine,and later carbon monoxide) provides the basis for judging
cigarettes lower and lower in smoke yield. In 1992, theEuropean Union legislated a maximum tar yield of 15 mg; thiswas lowered to 12 mg in 1998 and another reduction to 10 mg
is under consideration.14 15 Standard tests have contributed tocompetition for lower tar and nicotine cigarettes.9.............................................................
Abbreviations: BAT, British American Tobacco; FTC, Federal Trade
Commission; HSS, human smoking simulator; ISO, International
Organization for Standardization; PM, Philip Morris Tobacco Company;
PPU, puffing power units; RTD, resistance to draw; SPT, stain patterntechnique; TPM, total particulate matter

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Cigarette filter ventilation is a defective design becauseof misleading taste, bigger puffs, and blocked vents

Cigarette filter ventilationi41

To locate relevant industry documents, the following
databases were searched repeatedly from November 1999 to
10 November 2000: www.pmdocs.com; www.rjrtdocs.com;
www.lorillarddocs.com; www.bw.aalatg.com; www.cdc.gov/
tobacco/industrydocs; www.hlth.gov.bc.ca/Guildford; www.
cctc.ca/ncth/Guildford; www.cctc.ca/ncth/Guildford2; www.
tobaccodocuments.org; www.tobaccopapers.org. Key searchterms included: dilution, air dilution, filter dilution, ventilation, filter ventilation, tip ventilation, vent, vent blocking,occlusion, lip occlusion, insertion depth, puff volume, puff
parameters, resistance-to-draw, draw resistance, flow rate,
smoker–product interaction, smoking behaviour/behaviour,
product development (in conjunction with a particularbrand), focus group, test market, product testing, productevaluation, irritation, harshness, impact, taste, compensation,compensatory smoking, elastic, elasticity, compensatable/
compensatible, Actron, low tar, lowest tar, 1 mg tar, ultra light,
Light, lights, brand switching, switching study, Kozlowski,
FTC, testing, yield, tar yield, nicotine yield, CO yield, TPM,
delivery, smoke delivery, human smoking, simulator studies,human smoking simulator (HSS). When appropriate documents were found, names associated with the project (forexample, authors, supervisors, recipients) were used as searchterms to locate additional relevant documents.
We printed about 250 documents. One notes a preponderance of Philip Morris Tobacco Company (PM) documents. Thismay be because of the ease with which the PM archives could
be searched using keywords; other companies’ sites were lessuser friendly. Table 1 shows a chronology of documents used inthis review. This exhibit indicates the primary way in which
the document relates to one of the three themes of the review:(1) filter ventilation produces a lighter taste (“taste”); (2) filter ventilation causes larger puffs to be taken by smokers(“puff volume”); and (3) high levels of filter ventilation are
subject to blocking with lips or fingers (“vent blocking”).

DATA SYNTHESISFilter ventilation
For over three decades, cigarette filter ventilation has been the
major design feature for reducing the official machinesmoked, standard tar, nicotine, and carbon monoxide (CO)yields of cigarettes.14 16 Ventilated filters are now common on
cigarettes sold in the USA, Canada, and the UK, andmultivariate analyses indicate that ventilation has a major
effect on standard tar, nicotine, and carbon monoxide yields.4
Filter ventilation is not a specialised topic pertinent to only a
few cigarette brands. Lower standard tar cigarettes are nearly
always ventilated filter cigarettes and ventilated filter cigarettes are nearly always lower standard tar cigarettes.
Air dilution is introduced into the mainstream smoke bymeans of tiny vent holes on the filter.17 18 Essentially, smoke isreplaced with air in the standard puff, and this also causes lesssmoke to be produced at the burning coal.19 There are also
some subtler effects.20 The reduced draw on the burning cigarette coal also reduces the temperature of the coal, which canchange the nature of the smoke. The smoke moves throughthe filter at a lower velocity because of ventilation.21 Thereappear to be only two ways to reduce carbon monoxide yields:(1) increase filter ventilation or (2) increase cigarette paper
porosity (air flow through the paper itself). A manual for cigarette makers, “Cigarettes a la carte,” gives a good explanationof the basic principles.22 Using filter ventilation as a sole device
leads to many more puffs on a cigarette, because so little
tobacco is consumed with each puff of a heavily vented cigarette (for example, > 65% dilution). “Cigarettes a la carte”
explains that methods must be employed to increase the static

Table 1 Chronology of selected industry documents involving taste, puff volume,and vent blocking from various manufacturers 1955 to 1994*
Philip Morris
1955
1956
1959
1960
1967
1968
1969
1970
1971
1972
1974
1975
1977

RJ Reynolds

Lorillard

Puff volume 97
Puff volume 78
Puff volume 79
Puff volume 109
Puff volume 76 81
Puff volume 77 82 107

1978
1979
1980
1981
1982

Puff volume 88
Puff volume 103
Puff volume 74

1983
1984

Puff volume 80

1985
1986
1987
1989
1990
1994

BAT/B&W/Imperial

Puff volume 75 Taste 49
Taste 53
Taste 50 55
Taste 54
Puff volume 86 87
Vent blocking 125
Vent blocking 122

Vent blocking 123 124

Puff volume 108
Vent blocking 108
Puff volume 112

Vent blocking 120 121

Puff volume 101
Taste 59
Taste 47
Vent blocking 119

Puff volume 102

Puff volume 84
Vent blocking 130
Vent blocking 131
Puff volume 98

Puff volume 20

Taste 65
Taste 44 45

Puff volume 92
Puff volume 110

Puff volume 93 94
Puff volume 95 96
Puff volume 111

Puff volume 105
Taste 60

*The cites in this table are meant to be illustrative rather than representative of materials on this topic to befound on the internet. We have found that new documents are added frequently. We are not able tosummarise all the documents considered and have left out documents that in large part duplicate information
found in other documents (for example, separate reports of the same study).

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DATA SOURCES AND SEARCH PROCEDURE

i42

Development of ventilation
In 1983, PM conducted an internal seminar on the development of filter ventilation and low delivery cigarettes.23 Thisseminar describes the rapid rise of vented cigarettes in theUSA. PM’s first attempt at a ventilated cigarette occurred withSPUD in the mid 1950s, when three slits were introduced into
the paper before the filter. In 1970, Marlboro 100 was the first
PM product to use mechanical perforation in regular production, shortly followed by Alpine and Marlboro menthol 85s. In
terms of the overall market, only 7% of cigarettes were ventilated in 1975, rising to 20% by 1977. In 1980, ventilated filter
cigarettes represented 50% of the market. Eighteen months
later, 80% of cigarettes sold were ventilated—only 12% of filter
cigarettes were unventilated by 1982. By the time of the seminar, PM had introduced dilution into all filter cigarettes, as
had RJ Reynolds. Lorillard was diluting 94% of its filteredproducts. The American Tobacco Company (then an independent company) was diluting 57% of its filter cigarettes. Brown &Williamson, and Liggett were both using dilution in less thana third of their filter cigarettes. The report does not describe
ventilation trends in other countries, but notes that by 1981,
low tar cigarettes comprised 46% of the Canadian market andnegligible proportions in other countries.
Cigarette filter ventilation provides a straightforward, costeffective way to reduce the standard (as measured by FTC
and/or ISO methods) toxin yields of cigarettes.19 22 It was key
to compliance with the European Union’s regulations on
maximum tar yields.24 (Marlboro and Marlboro Light cigarettes have been found to have twice as much ventilation in
the UK as in the USA4). But, the official smoking test creates
yield numbers that have little relation to actual human smoke
exposures.1 25 26 Indeed, published smoker exposure studies
have seen little difference in biomarkers of exposure amongsmokers of Light, Ultra Light, and lowest tar brands.26 27 Recent
reviews of the disease effects of lower standard tar cigarettes
find little support for actual risk reduction as a result of theuse of such cigarettes.28 29
Numbers from official tar tests have given regulators theimpression that something was being done to reduce the toxicity of cigarettes to human smokers, while at the same timeindustry documents show that cigarettes were being designed
to be “elastic”—yielding more smoke to human smokers thanto smoking machines.1 5 It is excellent public relations forcigarette manufacturers to appear responsive to governmental
and consumer encouragement for less hazardous cigarettes. It
should be a public relations disaster to reveal that the industry was aware of compensatory smoking for decades, knew themachine tests underestimated actual smoke exposure, anddesigned cigarettes to beat the machines.1 2 5
Our review focuses on three main issues with low tar, ventilated cigarettes. Firstly, the effect of vents on the perceptionof “lightness” and “less irritation” is critical because it constitutes compelling (but misleading) sensory evidence that a low
tar cigarette really has lower tar. In other words, because
vented filter cigarettes feel milder, smokers act as if they areless toxic. This combines with the use of descriptors such as
Light or Mild to give a dangerous perception of risk reduction.
The second issue is that increased ventilation facilitates
increased puff volumes, a key means of compensatory smoking. For best selling, vented filter cigarettes in the Ultra Lightand Light range, increased puff volume can achieve compensation so well that behavioural vent blocking is superfluous.
The third issue is behavioural vent blocking, which isimportant when increased puffs will not comfortably provide
ample compensation. For two decades, Kozlowski andcolleagues have investigated the problem of filter vent
blocking with the lips and fingers of smokers.30–34 This research

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has made it clear that blocking as a means of increasing yield
applies mainly to the most heavily ventilated, lowest standard
tar cigarettes.35 36
The persuasive testimony of the senses: Lights do taste
lighter
The “lighter” taste of Lights became apparent to us during ournational survey research on smoker perception of Light andUltra Light cigarettes.37–41 Focus group participants37 told us
repeatedly and clearly that they thought Lights tasted lighterand milder and felt easier on the chest. For example, one participant described the aches in his chest he suffered if forced tosmoke Marlboro “Reds”, rather than his usual Marlboro
Lights, at parties. Such findings have been well known to theindustry for many years.42–47 Because of such dramatic perceptual evidence, smokers are understandably reluctant to accept
scientific findings that Light cigarettes are not less dangerous
than higher standard tar cigarettes. Smokers may believe that,
although others may not experience risk reduction by using
Lights, their perception tells them otherwise.
Filter ventilation tends to make cigarettes taste “lighter”,
thereby supporting the consumer’s perception that lower tar
cigarettes deliver less tar and nicotine as well as diminisheddangers to health. Air diluted smoke tastes, if you will,airier.16 48 The more air added by dilution, the milder and more
air cooled the smoke. This reduces the overall perception of“harshness” and increases the perception of mildness.37–39 49 50
A quote from a Philip Morris memo is telling. In describing
their reasons for ventilating cigarettes, a researcher notes that“ . . .if they [consumers] can see it’s longer burning—can taste
its mildness—and be shown it’s cooler, that this would bringcredibility to our advertising.”49
Mildness and lightness have been important marketingthemes to reassure smokers that cigarettes are less risky.51 The
popular theory of cancer around the turn of the 20th century
held that strong tobaccos caused oral cancers throughirritation.52 Cigarettes were promoted as a safer alternative tocigars because they were milder. Even before the introductionof filter cigarettes, mildness and lightness were important
advertising themes.51 The very first nationally advertised cigarette brand in the USA, RJ Reynolds’s Camel in 1913, was promoted as milder than other cigarettes of the day.51
Nearly 50 years ago in 1956, a confidential memo was written to the most senior executives at PM discussing “newproduct advantages for ventilated cigarettes”.53 These included
decreased carbon monoxide delivery and “subjectively decreased irritation by the smoke”. This theme of decreased irritation is echoed in other documents from the period.54 55 The
memo goes on to note: “Decreased irritation is desirable not
only from the subjective viewpoint but also as a partial elimination of a potential cancer hazard.”53 Of course, recent epidemiological evidence has found increases in certain lungcancers with lower tar cigarettes.56 57
In 1979, PM performed taste tests of ventilated and unventilated versions of regular Marlboro with equal standard tar
ratings. They found that the diluted version was rated as“milder” and better tasting.58 One year later, a British American Tobacco Company (BAT) study revealed that increasing
ventilation from 0 to just 12% significantly reduced “impact”
and irritation of the mouth, nose, and throat.59 A 1989 PM test
market study of a 9 mg tar (33% ventilation) Marlboro Lightin Korea found that the more ventilated cigarette was judged
milder and preferred to a regular Marlboro Light (11 mg tar,
25% ventilation).60 Given that smokers compensate easily forsuch small tar differences as a result of ventilation by increasing puff volume (see next section for an elaboration of thispoint), we expect that smokers were actually ingesting similar
concentrations of tar and nicotine from each version of Marlboro Light even though these lower standard tar cigarettes
tasted milder. The perception of lightness seems to derive, at

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burn rate—the amount of tobacco burned between puffs—todeal with this issue.22

Kozlowski, O’Connor

Cigarette filter ventilation

Bigger puffs are the key to compensation for mostventilated filter cigarettes
Cigarettes vary in how hard the smoker has to puff on them toproduce a given volume of smoke. An industry scientist noted
this is not an issue for smoking machines, which take a 35 ml
puff regardless of the effort involved.74 Other things being
equal, ventilated filter cigarettes have lower resistance to draw
(RTD). This effect was known as early as 1955, and isdiscussed in an internal Philip Morris memo on the effects ofearly ventilation designs.75 A lower filter RTD (and higher
dilution level) facilitates the taking of bigger puffs.76 77 Thismeans that smokers can easily take larger puffs on thecigarette with little added effort. To get an idea of the magnitude of the effect, consider Zacny and colleagues’ study.63 For
an unblocked (that is, fully ventilated—66%) 1 mg standard
tar cigarette the average RTD was 92.5 mm H2O. In contrast,
fully blocking the same cigarette (equivalent to making it
unventilated) doubled the RTD to 184.4 mm H2O.
RTD appears to have been a significant concern to low tar
cigarette designers in the 1970s and 1980s.76 78–80 Independent
research programmes at PM and BAT investigated the effects
of RTD on smoker behaviour, in particular puff profiles. At BATin 1972, Creighton led a number of studies on draw resistance,
ventilation and smoking behaviour.78 79 One found that“subjects took more puffs of very much larger volume from theventilated cigarette, but showed no difference in the way they
inhaled smoke.”79 Studies at PM concluded that there were
optimal dilution/RTD ratios for consumer acceptance.80
The dilution level of a ventilated cigarette determines how
large a puff smokers must take to compensate fully. A 1975 PM
study states that “filter dilution by itself causes a smoker tochange his puffing pattern.”81 Similarly, a 1977 PM study
found that “the dilution level itself influences the smoker’s[puffing] profile to a great extent.”[ 82] Sutton andcolleagues83 reported that the relation between dilution level
and compensating puff volume is curvilinear:
Percentage increase in puff volume = [% dilution/(100 −% dilution)] × 100.
As dilution increases, puff volume to compensate increases
exponentially. We can illustrate this simple model using

recently tested cigarettes from the USA, Canada, and the UK.4
Assuming a 35 ml standard puff, full compensation for the
dilution would be expected on a cigarette with 14% dilution(for example, Craven Full Flavor; Canada) with a small puff
volume increase (∼15%, from 35 ml to 40 ml). A smoker of
40% diluted Dorchester Extra Milds (UK) might need to takea 58 ml puff (a 67% increase) to achieve full compensation. In
contrast, on highly ventilated Carlton 100s (USA) or Benson &Hedges Ultra Lights (UK) (both ∼83% diluted), heroicallylarge 206 ml puffs might be required. The best selling cigarettein the USA, Marlboro Light, is just 23% diluted, and a puff ofonly 45 ml would likely fully compensate. The exact puff volumes needed for compensation are in practice somewhat
smaller than those estimated using this simple model. Higher
velocity, bigger puffs produce greater compensation than dolower velocity puffs of the same size.84
Increased puff volume is a very likely mode of compensation when it can be performed with only a modest amount ofeffort (that is, for a Light cigarette with low to moderate ventilation). For a heavily ventilated cigarette (for example, the
65% diluted, 1 mg tar), increasing to a puff volume within a
comfortable range (for example, about 50–80 ml) alone
generally would not provide adequate compensation. Hence,other forms of compensation become more important in thisclass of cigarettes. Also, the above figures are on a per puff
basis. For compensatory smoking, total puff volume per cigarette (puff volume per puff × number of puffs) is more important than the volume per puff.
The lighter feel of ventilated cigarettes may further
facilitate increased puff volumes because inhibitory oral andrespiratory cues are milder.85 When a smoker increases his puff
volume, he receives more smoke per puff from the cigarette(which compensates for reduced yield), but also receives more
air. The larger puff feels “lighter” to the smoker than if he hadtaken a smaller, more concentrated puff of equivalent yieldfrom an unventilated or less ventilated cigarette.
In 1967, scientists at PM wrote a memo: “A study of theeffect of air hole blockage on gross puff volume in air-diluted
cigarettes.”86 The mean “gross puff volume” for the test
cigarette without filter vent holes was significantly less(38.17 ml) than for the test cigarette with holes (45.48 ml).
The test cigarette was apparently 21% diluted, based onanother memo.87 They noted this as “further evidence thatsmokers adjust puff intake in order to maintain constantsmoke intake.”86 In short, smokers were taking larger puffs on
the ventilated cigarette. A PM study of a Merit-type cigaretteusing a human smoking simulator (HSS—a machine thatrecords smoker’s puff profiles and replicates them) showedthat the recorded human volume of 57.8 ml doubled the FTCtar (9 mg to 18 mg) and nicotine (0.62 mg to 1.3 mg) yields ofthe cigarette.88 Another PM HSS study notes that “standard
puffs of 35 cc volume repeated at one minute intervals are seldom seen among smokers.”77 Still another PM simulator study
noted that under simulated human smoking conditions (exact
parameters not reported) a 55% diluted 2 mg tar test cigarette
showed a tar yield increase of five times; a Now (65% dilution)
showed a six times increase over standard yield (2 mg); a
Carlton 70 (80% diluted) showed a yield increase of 10.5 times
standard yield (1 mg).80 Such findings have been observed
repeatedly, outside63 89–91 and inside77 82 92–105 the industry. In theearly 1980s, PM scientists concluded that “[r]esults from aseries of puff parameter manipulations made on the smoking
machine indicate that puff volume is the critical variable indetermining nicotine delivery to the smoker”.106
Much of the laboratory research on smoking has used cigarette holders to measure puff volume and puff numbers.107 108
This equipment prevents vent blocking with lips and shows
how much compensation is possible without vent blocking.
Two PM studies, for example, show how much puffing asmoker can do on a 1 mg tar cigarette if he cannot block vents.
In a study of college student smokers, one subject was

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least in part, from the level of ventilation present in the cigarette. One might wonder if the issue of behavioural vent
blocking (discussed below) is at odds with the issue of ventinduced lighter taste. After all, if vents were completely
blocked might not the cigarette taste become the same as its
unventilated counterpart? Sweeney and colleagues35 foundthat, indeed, blocked cigarettes were rated as significantly
harsher and hotter than unblocked ones. But most behavioural vent blocking is incomplete, often diminishing ventilation levels by 50% or 25%.61 62 While Zacny and colleagues63
reported that the unblocked 1 mg standard tar cigarette (thatis, fully ventilated) was rated as much less harsh than thesame cigarette fully blocked (that is, unventilated), a 50%
blocked cigarette received intermediate ratings—still lessharsh than a fully blocked cigarette.
Interestingly, consumers can be troubled if a lower tar cigarette has too strong a taste. Consider Brown and Williamson’s(a subsidiary of BAT) Barclay brand. Barclay has ventilation
channels that are subject to reduced ventilation whenever asmoker places the cigarette in the mouth.64 This compensatory
smoking system produces a strong taste, so much so thatmany lowest tar smokers rejected the brand.65 66
Ventilation is a key, but not the only, contributor to perceptions of cigarette harshness. The quality of the tobacco blend,chemical additives (for example, ammonia), cigarette circumference, moisture level, and even tipping paper colour havebeen found to influence a smoker’s perception of the strengthand irritation level of a cigarette.67–73

i43

i44

Vent blocking as an additional mode of compensation
In 1980, Kozlowski and colleagues began exploring the problem of smokers blocking filter vents, usually unwittingly, with
fingers or lips and increasing smoke exposures above standard
yield levels.30 Blocking 50% of filter vents increased standard
tar yields from 4.4 mg to 7.0 mg tar and nicotine from 0.45 mg
to 0.73 mg. Subsequent studies have found evidence of somewww.tobaccocontrol.com

Model of vent blocking
Vent blocking is more likely to occur in:
A. Cigarette designs in which:– (1) blocking increases nicotine and tar yields (generally,
the greater the ventilation level, the greater the effectof blocking on nicotine and tar yields)– (2) other forms of compensation (increased puff number,puff volume, or puff velocity) do not adequately compensate for reduced standard yields (this will be
more likely when ventilation level greater than 65%)
(cf 35)and
B. Smokers who:
– (1) seek nicotine and tar– (2) have had a chance to learn by trial and error theeffects of vent blocking (cf135)

degree of vent blocking in about 50% of vented cigarettes(Light or Ultra Light).32 34 85 112 114 115 Our more recent studies ofhuman smokers blocking vents have indicated that vent
blocking mainly has effects on smoke exposures (as measured
by expired alveolar carbon monoxide (CO)) in the lowest tar
and nicotine cigarettes (1–2 mg standard tar). Behavioural
blocking appears to have negligible effects on exposures inbest selling Light cigarettes (8–14 mg standard tar) and has
little effect on the Ultra Light brands studied (4–6 mg tar).35 36
Before continuing, consider the model of vent blocking
presented in the box below. This model presents vent blocking
as a product of cigarette design and smoker variables.
Industry scientists have challenged in print62 116 117 the assertion that smokers’ blocking filter vents with lips or fingers is a
substantial mode of compensation for low tar cigarettes.
Reading these published industry reports might convince onethat cigarette manufacturers have nothing to hide on thisissue. One might assume from their published reports that
their technical investigations have uncovered little to support
evidence presented in the peer reviewed scientific literaturesince the 1980s. One gets the impression of winning cards
being put on the table by the cigarette industry. These papers,
however, make no mention of the taste and puff volume issues
influenced by filter ventilation as discussed above.
The industry’s counter-arguments to the importance of vent
blocking primarily rest upon two assertions. The first claim isthat vent blocking does not happen very often. This argument
is based on saliva based estimates of mouth insertion depths,
which differ little between ventilated and unventilated
cigarettes. The second claim is that, on those rare occasions
when vent blocking occurs, it increases tar and nicotine yields
little because most blocking occludes at most 50% of vents. At
that level, they assert, the curvilinear effect of blocking on
ventilation level is relatively small.
We have found three main deficiencies in the public industry reports. Firstly, the saliva based measures are seriously
limited, underestimating mouth blocking and ignoring finger
blocking. Secondly, because the large majority of vented cigarettes do not have a high level of dilution, the lack of attention
to degree of ventilation instead of presence versus absence ofventilation obscures significant vent blocking effects in lesspopular, heavily ventilated cigarettes (that is, > 65% ventilated). Thirdly, the effects of vent blocking on tar and nicotine
yields vary from brand to brand depending on the complex ofdesign features—some show small effects, some large effects.
The published industry reviews may have used brands withrelatively small effects.
The industry scientists seem to have ignored the extensive
machine smoking studies by Rickert and colleagues on Canadian cigarettes,118 which have shown significant vent blocking
effects, particularly when more realistic smoking conditions

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observed to take a total puff volume of 1397 ml (number ofpuffs was not reported) from a single Carlton cigarette, while
the machine smoked volume was only 315 ml, over a fourfold
difference.109 Compare this to the total puff volume of 479 ml
taken by the same subject on a Marlboro, which had amachine smoked volume of 329 ml. The mean puff volume
across smokers of the Carlton was 713 ml. In a separate studyof an experimental 2 mg product, a subject was observed totake 100 ml puffs every 15 seconds on a Carlton, for a total
puff volume of 1399 ml on a single cigarette.107 These
individuals were working hard to smoke these cigarettes.
Industry scientists have also been interested in interactions
between ventilation type and puff volume. For example,
researchers at RJ Reynolds Tobacco Company compared laser,
mechanical, and electrostatic perforation types.20 Laser perforations were found to promote compensation with increased
puff volumes. That is, as puff volumes increased, filter air dilution decreased most notably with laser perforations. Other RJ
Reynolds researchers tested yield differences of different
tobacco blends with various perforation styles and equivalent
dilution levels.110 Cigarettes were smoked both according to
FTC procedures and “50/30” procedures (50 ml puff, every 30
seconds). Two rows of “slot” perforations gave the same nicotine (0.11 mg) as did two rows of “hole” perforations under
FTC conditions, but gave more nicotine under the “50/30”
condition: 0.67 mg (a 509% increase) versus 0.53 mg (a 382%
increase). Researchers at Lorillard noted that if a cigarette had
perforations arranged to cause flow turbulence in the filter,then smoke yields could be increased under intense puffing
more than would be expected volumetrically.111
Within the PM research programme, it was well known thatthe machines were not an accurate representation of humansmoking on low tar cigarettes and that filter ventilation
promoted compensatory smoking.109 In 1974, Helmut Wakeham, one of the most senior executives at Philip Morris, gavea presentation to stockholders. He explained, “people smokein such a way that they get much more than predicted bymachine. This is especially true for dilution cigarets.[sic]”109
Leading scientists at BAT knew the special value of filter
ventilation for compensatory smoking. Creighton conductedstudies comparing the effects of two methods of diluting cigarette smoke: paper porosity or filter ventilation. He found thatusing high porosity paper made it much more difficult forsmokers to compensate, because taking larger puffs would
actually reduce delivery.112 He noted that, while it would bepossible to compensate for paper porosity by using low velocity, long duration puffs, most smokers would not be able to do
this comfortably. However, he concluded: “ . . .a cigarette constructed with low paper porosity but with filter tip ventilation
would more readily allow a smoker to take a higher delivery ofsmoke by increasing the velocity of puffing.”112 Creightonsummarised that this would provide BAT with “a marketing
opportunity to offer a LOW to LOW TO MIDDLE delivery
product when smoked by machine, which could be a LOW TO
MIDDLE to MIDDLE delivery product when smoked by thesmoker.”112 BAT research also noted that the effects of puff volume increases were larger in higher dilution cigarettes.113
Filter ventilation is a key contributor to the phenomenon ofcompensation because of its effects of increasing the puff volume taken by smokers. The industry was well aware of suchvolume based compensation and appears to have designed
cigarettes to take advantage of it.

Kozlowski, O’Connor

Cigarette filter ventilation

Detecting vent blocking
In 1980, Kozlowski and others described a “stain pattern”
technique (SPT) for unobtrusively detecting the occurrence ofvent blocking with fingers or lips.30 Basically, this techniqueevaluates the tar stain on the mouth end of the filter, a stain

spreading toward the edge of the filter indicating the presenceof vent blocking. In cases of extreme blocking, one will note afairly uniform tar stain across the filter. Trained raters are able
to produce reliable and valid scores using this technique. The
SPT has been validated30 31 33 115 127 and can reliably detect thepresence or absence of vent blocking (but not degree of blocking, as was initially suggested) in many brands (Craven A
Special Mild, Carlton, Now, Virginia Slims Ultra Light, Virginia
Slims Light, Merit Ultima, Cambridge Ultra Light, Merit, BasicLight, Doral Ultra Light, GPC Ultra Light, Doral Light, Camel
Light). It does not work for Barclay which uses theplastic–vent–channel Actron filter. This filter was judged by a
US court as not able to be assessed by the FTC smoking
machine method because of the ease with which its
ventilation system could be compromised.64
Baker and Lewis62 note that the stain pattern can varybecause of factors such as hole size, hole depth, and number ofholes.128 129 But they present no evidence that this presents asignificant problem for SPT. They also cite work by Shibata(their reference 16), which suggests that the technique might
not work for cigarettes less than 69% ventilated—but,ironically, the Shibata research presented indicates that thepattern technique should work best for more heavily
ventilated cigarettes (the very brands proposed to be mostsubject to vent blocking). The stain pattern studies cited above
demonstrate that the system works for several popular brands.
The industry prefers saliva based measures of insertion depth
as an index of vent blocking.62 116 117 However, these methods
can be impaired by lip dryness and also miss finger blocking
entirely unless the smoker licks his fingers. Proponents admitthat up to 20% of imprints are unscorable.117

Hiding the few heavily vented cigarettes in a “haystack”
of lightly vented ones
The large majority of ventilated cigarettes are not highly
diluted (that is, < 40% dilution). Consider three popular
brands: Marlboro Lights, bestsellers in the USA (22.5%
dilution), Marlboro (10.2% dilution), and Winston (11.7%
dilution).4 Analyses that focus solely on differences between
vented and non-vented cigarettes obscure interesting effects.
Baker and Lewis conclude that insertion depths are the samefor ventilated and non-ventilated cigarettes—without attention to dose–response issues. A BAT Suisse study of cigarette
insertion depths130 notes: “Analysis of individual brands
clearly indicates that highly ventilated cigarettes are inserted deeply
into the smoker’s mouth and consequently the ventilation level isreduced during normal human smoking [emphasis added].” A
1 mg tar, 0.1 mg nicotine, 78% diluted brand had 43% of
insertion depths beyond the vents, while a full flavour brand(16 mg tar, 1.2 mg nicotine, 17% diluted) had only 22% ofscores beyond the vents (both brands had vents at
11–13 mm).130 Further, more fully blocked cigarettes were seenin the lowest yield category than any other category (fig 1).
Baker and Lewis62 also presented results from Canada (theirreference 20) to support the contention that insertion depths
do not differ between ventilated and unventilated products. A
CORESTA abstract131 found on the internet appears to refer tothis work and notes: “Insertion depths were greatest for cigarettes inthe very low delivery category [emphasis added].” Baker and Lewis
omit mention of these findings in their review.
Porter and Dunn116 of Canada’s Imperial Tobacco (a subsidiary of BAT) examined mouth insertion depths on cigarettebutts collected in Montreal, Toronto, and Vancouver. They
reported that the insertion depth difference between ventilated and unventilated cigarettes was negligible. Yet, between
4–10% of butts showed evidence of complete blockage, and
14–20% showed at least partial vent coverage.116 Insertion
depths by yield category were not separately considered. The
same year, Baker and colleagues117 found statistically reliable
differences in insertion depths with increasing ventilation

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are used. In Rickert’s study, puff volume was increased to
48 ml, puff duration was increased to 2.4 seconds, and puff
interval was reduced to 44 seconds. Under these conditions,lowest tar cigarettes (1 2 mg standard tar) showed a 130%(0.22 mg) increase in nicotine yield, while Ultra Light (3–5 mg
standard tar) and Light (6–14 mg standard tar) cigarettes
showed yield nicotine yield increases of 57% (0.31 mg) and
36% (0.41 mg) respectively when 50% of vents were
blocked.118 Tar yields in Lowest Tar cigarettes increased 160%
(2.5 mg), compared to 63% (4.0 mg) and 38% (5.5 mg)
increases in Ultra Lights and Lights. Carbon monoxide yields
in Lights increased by 36% (4.7 mg), while Ultra Light brands
increased 75% (4.9 mg); Lowest Tar brands increased 150%
(2.6 mg).
The industry researchers also have omitted details fromsome cited studies or any mention of other studies that
support the position that vent blocking is a problem. One
notable omission from Baker and Lewis62 is a 1982 BAT studyof vent blocking on a 1 mg tar cigarette smoked under various
puffing conditions.119 Experimenters systematically blocked
the vent area with patches of increasing size. Here, the datasuggest that vent blocking does significantly increase yields,
particularly under more realistic smoking conditions. Under
FTC conditions, the cigarette delivered 1.29 mg total particulate matter (TPM) unblocked, 1.69 mg half blocked, and8.44 mg fully blocked. If conditions were increased to “50/30”(50 ml puff every 30 seconds), the cigarette delivered 4.52 mg
TPM unblocked, 6.51 mg half blocked, and 20.9 mg fully
blocked.
Another BAT study not discussed by Baker and Lewis62 is
one by Creighton examining smoking behaviour on low delivery cigarettes.108 Creighton notes that, even with his small
number of subjects (n = 10): “There were some abuses of thecigarette design. These took place outside the behaviourallaboratory. It was observed that at least one subject learned
that by placing the cigarette further into the mouth, the ventilation holes could be covered up and smoke deliveries
increased. It was also noted that the fingers used to hold thecigarettes could be conveniently placed to cover up some of theventilation holes. One subject was seen to cover the ventilation holes
with clear adhesive tape”[emphasis added].108
We expect that Baker and colleagues were unaware of theinternal Lorillard memo from one scientist to a supervisor in
1977.120 Ihrig wrote to Schulz that he and colleagues had
devised a way to make 1–2 mg standard tar cigarettes actually
deliver around 4–5 mg tar to smokers. The system depended
on human lips covering filter vents that were not being
covered by the official FTC cigarette holder. Ihrig wrote: “Theseexperiments conclusively demonstrate the feasibility of a filter
bypass. Since filters can be designed to deliver more taste (tar)to the smoker than tests indicate, the current tar and nicotine
procedure is vulnerable to abuse . . .”120 It should be noted that
Schulz immediately rejected the idea as unethical.121 Ihrig laterwent on to join Norman in investigating puff volume effects
on compensation.93–95
PM conducted several studies on the effects of vent
blocking, both before and after the first peer reviewed studies
were published.122–126 In 1967, PM scientists noted that“ . . .some of these [ventilation] holes are likely to be occluded
under normal smoking conditions, whereas no occlusion is
likely to occur when the cigarettes are machine smoked foranalysis.”125 A study from 1982 notes that a Merit UL wentfrom 4.5 mg tar at standard conditions to 7 mg with 50% ofvents blocked by fingers.123

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i46

Kozlowski, O’Connor

31

Butts blocked (%)

30
25
20
15

10

10

6

6

5
0

16 mg tar,
1.2 mg NIC,
17% vent

9 mg tar,
0.7 mg NIC,
40% vent

4 mg tar,
0.4 mg NIC,
60% vent

1 mg tar,
0.1 mg NIC,
78% vent

Figure 1 Percentage of butts showing completely blocked vents on
various cigarette types (data from unpublished BAT Suisse study130).
Complete vent blocking was defined as by Baker and Lewis62 as
placing lips 4 mm or more beyond the ventilation zone. This figure
was created from insertion depth data.

levels. Ultra Light cigarette butts were 4.4 times more likely to
be completely blocked (6.5% Ultra Light v 1.5% Light). Standard cigarettes were inserted a mean of 7.8 mm, while Ultra
Lights were inserted 9.5 mm (22% deeper). However, theauthors downplay the differential prevalence of vent blockingby yield.
Ferris of BAT (cited by Baker and Lewis, their reference 17)
videotaped 133 British smokers of ventilated cigarettes.
Analysis of the videotapes showed that smokers’ fingers werein contact with the cigarette for all or part of a puff 12% of thetime, while during 81% of the puffs there was no finger
contact with the cigarette. Ten per cent of the puffs could not
be assessed. Looking at final puffs, 29% had smokers’ fingers
at least partially in contact with the cigarette. Overall, 11% ofparticipants had fingers in contact with the cigarette for atleast one puff. While viewing the videotapes, lip blocking was
not assessed. This is especially puzzling given that if one isfinger blocking a particular puff, one cannot be lip blocking(that is, the two actions are mutually exclusive on a givenpuff). A similar curious omission is noted in Philip Morris
studies of finger blocking.124 125 Philip Morris also appears tohave known early on that vent blocking may be inconsequential in less ventilated products. A 1982 study notes: “Thedecrease in dilution from covering a portion of the perforated
area can result in an increased delivery to the smoker of highly
diluted cigarettes even though the puff parameters decrease. For
cigarettes with lower dilution the increase in tar delivery is minimal[emphases added].”124
Working to derive nicotine from lower tar cigarettes
Smokers select cigarette brands for a variety of biological andpsychosocial reasons.132 A key biological factor is the psychoactive effects of nicotine from cigarettes. A key psychosocial factor is to smoke a brand that conforms to one’s self image.9 Thisself image can include concerns about diseases caused bysmoking, and it is clear that smokers tend to consider lower tar
cigarettes less risky.39 133 134 The industry has been aware thathigh desires to smoke a lower risk cigarette can make asmoker willing to work harder.92–95 For example, scientists at
Lorillard examined puff volumes (at standard FTC 35 ml as
well as 50 ml puffs) on lower tar cigarettes and had an elaborate language to describe the relation between puffing
regimens and yields. Norman and Ihrig93 summarised these
relations using “puffing power functions”. Puffing power units(PPU)—defined as the product of the flow rate and RTD(called “pressure drop” in the document)—served as a measure of the phenomenon. Basically, the increase in PPU

www.tobaccocontrol.com

represented the extra effort needed to obtain additional tar
from the cigarette. An understanding of puffing effort wasthought to be critical for very low yield brands, since thesewere the most likely to be smoked with extra effort to obtain
more smoke.
Standard tar yields can be seen as an indicator of how harda smoker has to work to achieve rewarding doses of nicotine.
Higher tar cigarettes (> 15 mg standard tar in the USA) provide the easiest access to nicotine. Light cigarettes (6–15 mg
standard tar) are still easy to get adequate nicotine from, but
require some additional (larger) puffing per cigarette. Ultra
Light cigarettes (3–5 mg standard tar) will require still more
puffing (that is, more effort). The “Lowest” tar category(1–2 mg standard tar) will require more work that mostsmokers are willing to do,92 and those high nicotine smokers
who fail to learn by trial and error to block vents may switch
back to higher tar cigarettes.132 135 But not all smokers of Lowest tar cigarettes are working to get high yields from thesecigarettes. Some smokers of these cigarettes are simply very
light smokers with low nicotine needs; others work hard byblocking filter vents and taking more and bigger puffs andsmoking more cigarettes per day to get adequate levels of
nicotine from these cigarettes.135
Industry research shows that smokers make trade-offs
between perceived safety and satisfaction from cigarettes.
Highly concerned individuals are more willing to put up withthe work needed to get nicotine and the less satisfying taste
from the Lowest yield cigarettes.45 136 Smokers of Light
cigarettes want a brand that makes them seem less foolish to
be still smoking, but they do not want to work too hard for
nicotine or taste satisfaction.42 137–139

DISCUSSION AND CONCLUSIONS
Filter vents are both an effective design feature for the industry and a tragedy for the smoker seeking a less hazardous
smoke. The industry gets an inexpensive-to-make cigarettethat beats the standard tar tests,1 reassures smokers with alighter taste, and facilitates the taking of bigger, compensating
puffs. Smokers can take false comfort from a lighter taste anda consoling name (such-and-such Ultra Light or Light); andtheir smoking is sustained by satisfaction from bigger puffs on
the majority of low tar cigarettes and from blocking filter ventson the relatively rare “Ultra Ultra” Lights (> 65% air diluted,
1–2 mg standard tar). Cigarettes continue to sell. Smokers
continue to die at an undiminished rate.28 56
Some limitations of reviewing industry documents
We do not know what further documents are due to be postedon the internet. We could find documents one day that had notbeen there the day before, searching on the same keywords.
Many of the websites do not permit searches for words withindocuments: If one of our key words did not appear in the title,
we may have failed to locate some useful papers that wereavailable. If we had the time to read every document on theinternet, we may well have found more information relevant
to ventilation. When researching our comments on Baker andLewis,62 we noted that some industry studies they cited were
nowhere to be found on either the industry or non-industry
websites.
Stop using vents to appear to reduce harm to smokers
If we imagine that manufacturers were motivated to reduce
harm to their customers, then the lower tar (vented filter)
cigarette should be judged a complete failure. Some of the best
evidence of the failure of filter ventilation as a health protecting design feature comes from tobacco industry reports andmemos that have been only recently become available becauseof litigation. Given the triple threat to cigarette smokers(deceptive taste, facilitated puffing, and vent blocking), theventilated filter cigarette may simply be too dangerous to

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35

Cigarette filter ventilation

Health and consumer groups should commission theirown two stage testing of cigarettes
Kozlowski and O’Connor1 proposed a two stage machinesmoking test. The first stage would be a current standard test(with a maximum tar yield of 10 mg and maximum nicotine
yield of 1.0 mg). It was proposed that for every 0.1 mg below a
1.0 mg nicotine standard yield the puff volume would be
increased by 4 ml and the puff frequency decreased by four
seconds. A 0.1 mg standard nicotine cigarette would besmoked with a 76 ml puff every 24 seconds. (These parameters
are best estimates in lieu of further machine studies.) Filter
vents would be 50% blocked for machine smoking unless clear
instructions are given not to block vents and the vents areclearly marked. While in the best of all possible worlds one
would prefer a test involving biomarkers and observation ofhuman smokers linked to specific brands, such assays would
take years to develop and be very expensive to use. A two stage
machine test, despite clear limitations, could be implemented
in the near future. There is no need to wait for the tobacco
industry to agree to “compensating” test standards. Such a
procedure could take years and might get nowhere. Just as
consumer groups (for example, the Consumers Union in theUSA) publish the results of their own tests of products, often
according to their own procedures, they could do tests of cigarettes that might better inform consumers. Any group is free
to say that when cigarettes are tested in fashion X, one gets
results Y; biases should be toward consumer protection rather
than corporate gainsaying.
Cigarettes should be discouraged as a nicotine delivery
systemSmoked tobacco products are much more dangerous to publichealth than are other nicotine delivery systems.141–143 Even if
filter vents were eliminated as a design feature, how would
compensating puff volumes or puff numbers be controlled?
How would fire risks144 or second hand smoking risks145 becontrolled? To fret about designing a “safer” cigarette and toinvest further research into controlling specific toxins incigarettes146 may end up being little more than a make work
programme for toxicologists who will spend years assessing
how many nitrosamines and polyaromatic hydrocarbons
dance in a chromatograph (cf.147). Further research into
“safer” cigarettes would serve as a stalling tactic for theindustry. From the late 1960s to the late 1970s in the USA, theNational Cancer Institute worked in close cooperation withthe tobacco industry in an organisation called the Tobacco
Working Group.148 Among the scientists involved were Gio
Gori, Dietrich Hoffman, Ernst Wynder, Helmut Wakeham(PM), and Alan Rodgman (RJ Reynolds). Programme
direction came from the National Cancer Institute. Mouseback painting studies were used to evaluate the toxicity ofmany strains of tobacco. This project is generally viewed as acomplete failure to identify a “less hazardous cigarette”. Decades of effort have been put into less hazardous cigarettes.

What this paper adds
Filter ventilation is a nearly ubiquitous design feature incigarettes. Smokers increase puff volume, number of puffs,
and number of cigarettes smoked, and block filter vents tocompensate for the smoke yields of lower tar cigarettes asmeasured by standard smoking machine tests.
This paper explains the complex role of filter ventilationin compensatory smoking as seen in industry documents
and published research. Ventilation is found to causelighter taste, promote larger puffs, and, with heavy ventilation, promote behavioural blocking of vents. Filter vents
are judged to be a defective, misleading design feature.
Policy and regulation of cigarettes needs to attend to the
problems of filter ventilation.

Research and development should be directed toward efforts
to find non-burned, non-smoked, nicotine delivery
systems143–147 and to encouraging current smokers to use suchproducts instead of cigarettes.149
Lower tar cigarettes should be aggressively countermarketed
Evidence is beginning to appear that counter marketing Light
cigarettes can be effective.37 133 The most effective countermarketing efforts may be those that acknowledge theconsumer’s sensory evidence that Lights feel less harsh thanregular cigarettes.37 Results of consumer protection focused
cigarette tests (see above) could also aid in countermarketing.
In conclusion, vents reduce machine smoked tar and nicotine yields exquisitely. Yet, smokers of standard lower tar cigarettes do not generally get reduced smoke toxin exposures or
improved prospects for avoiding tobacco caused death anddisability. Research inside and outside the tobacco industry
has shown that filter ventilation is a key design feature for themodern lower tar cigarette. We reviewed three special andpowerful effects of filter vents that contribute to the dangers ofthese cigarettes. Firstly, and possibly most noteworthy,
ventilated filter cigarettes taste lighter and milder than theirunvented counterparts. This lighter taste provides concrete
and ill founded reassurance to the Light smoker. Secondly, filter ventilation facilitates compensatory smoking by promoting the taking of bigger puffs. Thirdly, vent blocking appears to
be a substantial problem on 1 mg tar, heavily ventilated cigarettes, in addition to promoting still larger puffs. Filter ventilation is an ingenious device for an industry that acts toappease regulators and satisfy consumers. It directly reduces
standard toxin yields, while at the same time it carries tohuman beings a false sense of security through the milder
taste and continued risk through bigger puff volumes andbehavioural vent blocking on the most heavily vented brands.
Filter vents should be recognised as a deceptive and defective
design feature and their use banned. Governments shouldtake ventilation into account in regulatory structures, particular yield maximums. Health interested groups should test
cigarettes in a way that reflects compensatory smoking. Lower
tar (vented filter) cigarettes should be discouraged as a harm
reduction product and actively counter-marketed.

ACKNOWLEDGEMENTS
Thanks go to Andrew Strasser for his comments on earlier drafts ofthis manuscript.
.....................

Authors’ affiliations
L T Kozlowski, R J O’Connor, Department of Biobehavioral Health, The
Pennsylvania State University, Pennsylvania, USA

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countenance. Arguably the most important design feature in
the modern low tar cigarette not only fails to significantly
reduce smokers’ exposure to toxins, but also misleadingly
reduces their health concerns. Filter ventilation, an explicitly
defective and deceptive design feature, should be banned as ameans of reducing machine smoked yields.
Increased filter ventilation levels can be expected in thosecountries that are lowering the maximum allowable standard
tar and nicotine yields.24 Countries considering such maximums also ought to regulate which design changes are
permissible to achieve these yields. Prohibiting filter ventilation would require manufacturers to achieve those reductions
by other means. The supposedly novel designs of Eclipse andAccord140 are ventilated. Governments considering regulationof novel devices should also disallow ventilation as an acceptable design feature on these products.

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