Charcoal filters in cigarettes: safer or just a marketing gimmick?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Eligible subjects will be: 1. Male and female smokers who are at least 21 years of age and self-report smoking at least 5 cigarettes per day for at least the past 6 months. 2. Smokers of primarily non-menthol cigarettes of brands other than Natural American Spirit. 3. Not currently undergoing smoking cessation treatment or trying to quit. 4. Able to communicate fluently in English (speaking, writing, and reading). 5. Capable of giving written informed consent, which includes compliance with the requirements and restrictions listed in the combined consent and HIPAA form. Exclusion Criteria: * Subjects who self-report and/or present with the following criteria will not be eligible to participate in the study: Smoking Behavior 1. Use of menthol or Natural American Spirit cigarettes as preferred/regular brand (defined as using \>20% of the time). 2. Enrollment or plans to enroll in a smoking cessation program in the next month. 3. Provide an initial Carbon Monoxide (CO) reading \< 5 parts per million (ppm). Alcohol/Drugs 1. History of substance abuse (other than nicotine) in the past 12 months and/or currently receiving medical treatment for substance abuse. 2. Current alcohol consumption that exceeds 25 standard drinks/week. Medical 1. Women who are pregnant, planning a pregnancy, and/or lactating. 2. Any impairment including, but not limited to, visual, physical, and/or neurological impairments preventing the completion of procedures included within this protocol. Notable impairments will be evaluated by the PI and eligibility will be determined on a case-by-case basis. 3. Color blindness. 4. Serious or unstable disease within the past 12 months (e.g. heart disease, cancer). Applicable conditions will be evaluated by the Principal Investigator and eligibility will be determined on a case-by-case basis. Psychiatric As determined by self-report: 1. Lifetime history or current diagnosis of psychosis, bipolar disorder, and/or schizophrenia. 2. Current diagnosis of major depression. Subjects with a history of major depression, in remission for 6 months or longer, are considered eligible. Other Additionally, participants may be deemed ineligible for any of the following general reasons at any point throughout the study, as well as during the initial telephone screen, at the discretion of the PI: * Significant non-compliance with protocol and/or study design. * Past, current, anticipated, or pending enrollment in another research program over the study period that could potentially impact study data. * Any medical condition, illness, disorder, adverse event (AE), or concomitant medication that could compromise participant safety or significantly impact study performance.