Effects of CO Level on Pain, Sensory Function, and Subjective Health

NCT07571941 | Not Yet Recruiting

• 1 other identifier: 2026/3-6
• Study Type: observational
• Target: 70
• Locations: 0 countries
• Sites: N/A

Brief Summary

Carbon monoxide (CO) is a colorless and odorless gas that can enter the human body through environmental exposure and especially tobacco use. CO binds to hemoglobin with a much higher affinity than oxygen, thereby reducing oxygen transport to tissues. This condition may lead to various physiological and psychological effects, particularly on the nervous system. In the literature, CO exposure has mainly been investigated in the context of acute poisoning cases and smoking-related effects. However, studies evaluating the effects of low-level and chronic CO exposure-more commonly encountered in the general population-on pain perception, sensory functions, and psychological status are limited. Tobacco smoke is an important source of CO, and exhaled CO levels have been shown to be significantly higher in smokers and associated with various neurocognitive changes. Evidence suggests that CO exposure may influence anxiety, depression, attention, and cognitive functions. In addition, some studies indicate that CO may affect brain regions involved in pain perception and emotional regulation. However, there is insufficient research examining the relationship between low-level carbon monoxide exposure and pain threshold, sensory functions, anxiety, depression, and subjective health complaints within the same study framework. This study aims to evaluate the relationship between exhaled carbon monoxide (CO) levels and pain threshold, sensory functions, anxiety, depression, and subjective health complaints in healthy adults. By examining the multidimensional effects of low-level CO exposure, the study seeks to fill an important gap in the literature and provide a more comprehensive understanding of this issue.

Conditions

Carbon Monoxide, Pain Perception, Sensory Thresholds, Anxiety, Depression, Tobacco Smoking

Keywords

CO exposure; exhaled carbon monoxide; pain threshold; sensory function; smoking and CO; healthy adults

Outcome Measures

Primary Outcomes (1)

• Exhaled Carbon Monoxide (CO) Level

  Exhaled carbon monoxide levels will be measured using a Bedfont Smokerlyzer-piCO+ device. Participants will be instructed to take a deep breath, hold their breath for 15 seconds, and then exhale slowly and completely into the device mouthpiece. The measured CO values will be classified as follows: 0-6 ppm: non-smoker 7-10 ppm: light exposure 11-15 ppm: regular smoker 16-25 ppm: heavy smoker 25 ppm: very heavy smoker

  June 2026- July 2026

Secondary Outcomes (6)

• Pain Threshold Measurement

  June 2026- July 2026

• Beck Anxiety Inventory (BAI)

  June 2026- July 2026

• Beck Depression Inventory (BDI)

  June 2026- July 2026

• Semmes-Weinstein Monofilament Test

  June 2026- July 2026

• Subjective Health Complaints Inventory

  June 2026-July 2026

Study Arms (1)

Healthy Adults - CO Exposure

This cohort includes healthy adult participants. No intervention is applied. Participants will be assessed for exhaled carbon monoxide (CO) levels, pain threshold, sensory functions, anxiety, depression, and subjective health complaints. The study aims to investigate the association between low-level CO exposure and physiological and psychological outcomes.

Eligibility Criteria

• Age: 18 Years - 65 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

This study will include healthy adult participants aged 18-65 years with a history of regular smoking for at least the past 6 months. Participants will be free of respiratory, cardiovascular, neurological, and psychiatric diseases, and will not have any acute infection or recent surgery affecting respiratory muscles.

You may qualify if:

• Being between the ages of 18 and 65
• Having a regular smoking history for the past 6 months
• No history of respiratory, cardiovascular, or neurological/psychiatric diseases
• No recent surgery or trauma that could affect respiratory muscles
• Not having an acute infection (especially upper or lower respiratory tract infection)

You may not qualify if:

• Having chronic respiratory diseases such as COPD or asthma
• Having a history of cardiovascular disease
• Having a diagnosed neurological or psychiatric disorder
• Having a history of surgery or trauma affecting respiratory muscles within the last 3 months
• Being pregnant or having a suspicion of pregnancy

Sponsors & Collaborators

• Izmir Democracy University: lead

MeSH Terms

Conditions

Anxiety Disorders; Depression; Tobacco Smoking; Smoking

Condition Hierarchy (Ancestors)

Mental Disorders; Behavioral Symptoms; Behavior; Tobacco Use

Central Study Contacts

Betül Taşpınar, Professor

CONTACT

+90 506 680 44 26

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Professor

Study Record Dates

• First Submitted: April 30, 2026
• First Posted: May 7, 2026
• Study Start (Estimated): June 1, 2026
• Primary Completion (Estimated): July 1, 2026
• Study Completion (Estimated): September 1, 2026
• Last Updated: May 7, 2026

Record last verified: 2026-04

Data Sharing

• IPD Sharing: Will not share