Dutt, Gogia, and Gupta: A study on pulmonary function tests in smokers and after cessation of smoking (Quitters)


According to the reports published by World Health Organization (WHO) tobacco smoking killed 100 million people worldwide in the 20th century and that it could kill one billion people around the world in the 21st century also.1 In India smoking is a common habit prevalent in both urban and rural areas irrespective of mode of smoking. Tobacco has remained as one of the most important predisposing factors responsible for so many respiratory and cardiovascular diseases. Smoking leads to rapid decline in pulmonary function tests (PFTs). Smoking is the single most significant risk factor contributing to the development of COPD.2 Chronic Obstructive Pulmonary Diseases (COPD) recognized as one of the most important causes of morbidity and mortality in chronic tobacco smokers. Smoking affect small airways are less than 2mm in diameter andleads to decline in Forced vital capacity (FVC) and Forced Expiratory Volume in the First Second (FEV1) the two most important lung function test parameters.2 On an average, cigarette smokers have a high annual rate of decline in FEV1 of about 50 ml, which is nearly double the average value of 30 ml annually present in non-smokers.3 Smokers who quit smoking reduce their risk of developing and dying from tobacco-related diseases and progression to COPD.2 Approximately 70 percent of smokers say that they want to quit, and over 50 percent of Smokers report that they tried to quit in the past year. Quitting smoking early may help reduce the effects of smoking on decline of lung functionsand may reduce the morbidity and mortality associated with Smoking. Being unexpensive, non-invasive and reproducible and cause minimum discomfort to the subjects, pulmonary function testing is a routine test for assessing Pulmonary functions. Spirometric values vary according to age, height, sex, and body size. Thus, cigarette smoking has extensive effects on respiratory function, which can be detected with pulmonary function test. The aim of the study was to compare the pulmonary function among smokers and non-smokers and Quitters.

Material and Methods

A cross-sectional study was conducted in the department of Physiology of Tertiary level health care institute in Greater Noida from June 2019 to November 2019. A total of 250 male subjects were included in the study including 100 smokers, 100 Nonsmokers and 50 quitters who visited or working in the institution. A pretested semi-structured questionnaire was used to gather information regarding smoking habits, occupation, medical history etc. The individuals were enrolled in the study as per the following inclusion & exclusion criteria.

Inclusion criteria

  1. Non-smoker: According to definition non-smoker is a person who does not smoke tobacco.

  2. Smoker: They are persons who are engaged in the inhalation and exhalation of fumes of burning tobacco from cigarette. Every smoker must have been smoking at least one cigarette a day for one year.

  3. Quitter: Former smoker who has not smoked at least for last six months

  4. Age 18-60 years.

Exclusion criteria

  1. Those suffering from respiratory or cardio-vascular diseases like bronchial asthma, pulmonary tuberculosis, Pleurisy, chronic obstructive airway disease.

  2. The person who have history of cough with sputum, haemoptysis or are ill.

  3. The person with occupational history of working in mills and factories or other places where lungs are affected by dust or fumes.

  4. Those with a history of hospitalization with chronic ailment.

Spirometric manoeuvre RMS Helios 401 Spirometer was used for evaluating the respiratory functions. The subjects were asked to sit comfortably on a chair. The complete procedure was explained and the subjects were instructed to breathe in fully by deep inspiration with their nostrils closed, to seal their lips around the sterile mouthpiece of the spirometer and to forcefully expire air out. The three consecutive readings were recorded and best of the three was used for the study.

Following activities were avoided prior to test, according to American thoracic society (ATS) guidelines.

  1. Smoking with in 1 hour of testing.

  2. Consuming alcohol within 4 hours of testing.

  3. Performing vigorous exercise within 30 mins of testing

  4. Wearing clothing that substantially restricts full chest and abdominal expansion.

  5. Eating a large meal within 2 hours of testing.

The ethical clearance was obtained from the institutional ethical committee and data was collected& the results were analysed with epi info 7 software using appropriate statistical methods.


Table 1

Age and sex distribution

Physical characteristic

Nonsmoker male (Mean±SD)

Smokers male (Mean±SD)

Quitters (Mean±SD)


36± 8.12



Height (in centimetres)

159.64± 0.51







All the subjects included in the study were of almost the same age & physical characteristics.

Table 2

Comparison in FVC and FEV1 between smokers and nonsmokers

Pulmonary Functions

Smokers N= 100

Non-smokers N= 100





significant ˂.05




Highly significant ˂.001

There was significant decline in FVC and FEV1 in Smokers in comparison to nonsmokers.

Table 3

Comparison in FVC and FEV1 between smokers and quitters


Smokers N=100

Quitters N=50
















The FVC and FEV1 parameters of pulmonary function showed significant difference between Smokers and Quitters. They were significantly high in case of Quitters.

Table 4

Comparison of FVC and FEV1 in Non-smokers and Quitters (males)

Pulmonary Function

Quitters N=50

Non-smokers N=100









Not significant






Not significant

There was no significant difference in FVC and FEV1 between Nonsmokers and Quitters.


The results in the study show that there was significant decrease in pulmonary function(FVC and FEV1) in Smokers as compared to Nonsmokers. It is consistent with the findings, Bano et al.3 and similar studies.4, 5, 6

FVC and FEV1 did not show any significant difference between quitter and Nonsmokers. Brchfiel et al.7 published similar findings rate of decline of FEV1 after 2years of smoking cessation was similar to Nonsmokers.

Further FVC and FEV1 were significantly lower in smokers as compared to quitters. It shows the benefits of cessation of smoking as has been found in other studies like Aldo Pezzuto et al8 who reported significant increase in FEV1 after3 months of cessation of cigarette smoking. Similarly, Peter Lee et al.9 also showed significant decline in smokers as compared to Quitters. Finding in our study is consistent with these previous studies.

It has been shown in many studies that performing pulmonary tests helps in quitting smoking especially in persons with advancing age and these tests show obstruction.10


Smoking leads to decline in FVC and FEV1. Cessation of smoking leads to improvement in lung functions and it may be not much different FVC and FEV1 in Nonsmokers. Quitting smoking may help in improvement of Pulmonary function and may reduce the sharper decline in FVC and FEV1 in Smokers and thus may help abetting the complications of morbidity and mortality associated with smoking. Showing Lung Function tests result to smokers helps in smoking cessation.

Source of Funding


Conflict of Interest

None declared.



WHO report: Tobacco could kill one billion by 2100Science Daily20082471


Global initiative for chronic Obstructive Lung Disease. Global strategy for the diagnosis, management and prevention of chronic obstructive Pulmonary diseasehttps://goldcopd.org/wp-content/uploads/2017/11/GOLD-2018-v6.0-FINAL-revised-20-Nov_WMS.pdf


R Bano AM Mahagaonkar NB Kulkarni N Ahmad S Nighute Study of pulmonary function tests among smokers and non-smokers in a rural areaPravara Med Rev200941116


MM Patel JA Sisodia NT Shah A comparative study of spirometry in healthy smokers and healthy non smokersInt J Res Med201436870


S Nighute A Awari Study of pulmonary function test in smoker and non-smoker in rural area of GujaratJ Clin Diagn Res2011511513


R Dhand SK Malik PK Sharma Long term effects of tobacco smoking: Results of spirometric study in 300 old menIndian J Chest Dis Allied Sci198527449


CM Brchfiel Effects of smoking and smoking cessation on longitudinal decline in Pulmonary FunctionAm J Respir Crit Care Med19951516177885


A Pezzuto M Stellato G Catania C Mazzara S Tonini M Caricato Short-term benefits of smoking cessation along with Glycopirronium on lung function and respiratory symptoms in mild COPD patients: a retrospective studyJ Breath Res201812404600710.1088/1752-7163/aad0a8


PN Lee JS Fry Systematic review of the evidence relating FEV1decline to giving up smokingBMC Med201088410.1186/1741-7015-8-84


B Salepci B Caglayan A Fidan ET Parmaksiz N Kiral SS Comert The Effect of Pulmonary Function Testing on the Success of Smoking CessationRespir Care2016618107380


© This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

  • Article highlights
  • Article tables
  • Article images

Article History

Received : 06-03-2021

Accepted : 09-03-2021

Available online : 06-07-2021

View Article

PDF File   Full Text Article

Copyright permission

Get article permission for commercial use


PDF File   XML File   ePub File

Digital Object Identifier (DOI)

Article DOI


Article Metrics

Article Access statistics

Viewed: 288

PDF Downloaded: 111

Wiki in hindi