Abstract
Context:
Pollution-related health hazards are very common among people living and/or working in industrial areas, particularly near industries and metro cities. These air pollutants contribute to allergens, increase inflammation, and affect lung function.
Aim:
The present study aimed to examine the effect of yoga training on lung functions and inflammation in terms of soluble interleukin-2 receptor (sIL-2R) in people working and living in a polluted area.
Settings and Design:
This is a randomized controlled interventional pilot study.
Methods and Materials:
Forty-eight male volunteers from the industrial area, aged 20–50 years, were randomly assigned to the experimental group and the control group. Each group comprises 24 study participants. Lung function and sIL-2R were studied at the baseline and post-yoga intervention period of 16 weeks.
Statistical Analysis Used:
Study data were analyzed using descriptive methods, a one-tailed t-test, a paired t-test, and an independent t-test.
Result:
Study results showed directional and significant improvements in forced vital capacity, forced expiratory volume in the first second, and peak expiratory flow rate compared to the control group participants. The results pertaining to sIL-2R showed a directional and significant decrease in the experimental group compared to the control group.
Conclusion:
The present study showed that yoga helps to promote better health, improve lung function and reduce inflammation among people residing in polluted environments.
Keywords: Air pollutants, inflammation, lung function, sIL-2R, yoga
INTRODUCTION
Industrial areas and metro cities of developing and developed countries are highly polluted zones. Exposure to these pollutants is harmful and may cause serious diseases like asthma, allergies,[1,2] cardiovascular diseases,[3] neurological diseases,[4] etc., The pollution affects the development of the fetus in pregnant women;[5] in kids, it causes poor concentration, ADHD,[6] etc., It also increases hospital admissions due to respiratory illnesses.[7]
The common air pollutants emitted by these industries are CO, sulfur oxides, lead particles, particulate matter (PM10 and PM2.5), various gases such as ground-level ozone (O3), nitrogen oxides (NO2 or NOx), volatile organic compounds, ultrafine carbon black, etc., The pollutants’ concentration and types may vary depending upon the type of industries in that area. People living and working in such a polluted environment are at high risk of developing the pulmonary disease as they are exposed to ambient air pollution for more than 10 h in a day or the whole day compared to people living in areas distant from the industries.[1] Apart from this, the people living in these areas are usually from low socioeconomic status[8,9] and are less educated,[10,11] have less health awareness,[12] stressful life[13] and also unaware of primary health care for working and/or living in such a polluted areas make things worse for their health conditions. Yet, there are certain preventive ways to reduce the harmful effects of pollutants. In such circumstances, along with primary health education,[14] a small complementary/alternative therapy such as yoga may help to improve the health status of the people living near industrial areas or other polluted zones.[15]
Yoga practices are found to be a useful tool in cleansing the respiratory tract,[16,17] helping to lower inflammation[18] and thereby improving overall health.[19] It was also observed that yoga practices help reduce prooxidants[20] and balance the levels of anti and pro-inflammatory cytokines, thereby improving immune response.[18,21]
The main aim of this study was to assess the effect of yoga practices on the measures of lung function and inflammation in terms of pro-inflammatory cytokine marker soluble interleukin-2 receptor (sIL-2R) among the residents in the polluted industrial zone, as well as to compare the results with the non-yoga-practitioners in the same period and environmental conditions.
Objectives
To examine whether yoga training significantly improves the lung function of people living/working in the industrial area.
To examine whether yoga training reduces the pro-inflammatory cytokine sIL-2R among people living/working in the industrial area.
METHODS
Forty-eight male participants, living and working in the industry, were recruited for the study. Only healthy male participants of age 20–50 were selected by the medical doctor after taking a brief medical history. Individuals already doing exercise/gym, swimming/yoga/aerobics/sports, etc., individuals addicted to smoking, alcohol, or any other drug addictions, and those who went through major surgery, having cardiovascular disorders, diabetes, physical disabilities, autoimmune diseases, immune-compromised diseases, cancer, schizophrenia, etc., were excluded from the study.
The study was approved by the Institutional Ethics Committee of the institute, and the trial was registered with the Clinical Trial Registry, India (the registration number is provided in the cover letter). Participants were screened from the Nangargaon industrial area, Pune, Maharashtra. Written informed consent was obtained from all the study volunteers.
The present trial is a randomized, controlled, two-arm, interventional pilot study. A total of 110 volunteers were present for the primary screening out of 135 volunteers. Eighty participants were eligible for the study. Forty-eight individuals took part in the pre-testing, having been randomly assigned to two groups, an experimental group and a control group [Figure 1]. The experimental group underwent a 16-week yoga intervention [Table 1] six times a week for an hour in the evening. At the same time, the control group was waitlisted for the said period. The yoga intervention for the experimental group was provided by an experienced senior yoga teacher.
Figure 1.
Study design
Table 1.
Yoga intervention protocol
| Daily yoga practice for 16 weeks (six days a week) | |
|---|---|
|
| |
| Name | Duration |
| Shanti path (prayer) | 2 min |
| Shavāsana (corpse pose) | 2-5 min |
| Pavanamuktasan (gas-releasing pose) | 5 s initially, adding 5 s per week until 45 s |
| Viparita karani (inverted pose) | 5 s initially, adding 5 s per week until 45 s |
| Matsyāsana (fish pose) | 5 s initially, adding 5 s per week until 45 s |
| Ardh-halāsana (half plow pose) | 5 s initially, adding 5 s per week until 45 s |
| Setubandhāsana (bridge pose) | 5 s initially, adding 5 s per week until 45 s |
| Naukāsana (boat pose) | 5 s initially, adding 5 s per week until 45 s |
| Bhujangāsana (cobra pose) | 5 s initially, adding 5 s per week until 45 s |
| Shalabhāsana (full locust pose) | 5 s initially, adding 5 s per week until 45 s |
| Dhanurāsana (bow pose) | 5 s initially, adding 5 s per week until 45 s |
| Ardhamatsyendrāsana (twisted pose) | 5 s initially, adding 5 s per week until 45 s |
| Gomukhāsana (cow face pose) | 5 s initially, adding 5 s per week until 45 s |
| Paschimotānāsana (seated forward bending pose) | 5 s initially, adding 5 s per week until 45 s |
| Ushtrāsana (camel pose) | 5 s initially, adding 5 s per week until 45 s |
| Vrikshāsana (tree pose) | 5 s initially, adding 5 s per week until 45 s |
| Tadāsana (mountain pose) | 5 s initially, adding 5 s per week until 45 s |
| Kapālabhāti (nādi cleansing practice) | Three rounds of 80 strokes initially, progressively up to three rounds of 120 strokes. |
| Ujjayi Prānāyāma (victorious breath) | 10 rounds |
| Bhramari Prānāyāma (humming bee breath) | 10 rounds |
| Anuloma-Viloma Prānāyāma (nādi cleansing practice) | 10 rounds |
| Om Chanting | 5-8 min |
| Shavāsana (corpse pose) | 5-8 min |
| Shāntipath (prayer) | 2 min |
Relaxation with Shavasana/Makarasana of 30–45 s after each asana practice
All the study participants were instructed to follow their earlier regular routine. Yoga was administered only to the experimental group. The study participants were not instructed in any way regarding their diet or other activities.
All the study variables were assessed twice at the beginning of the study, before the yoga intervention, and at the end of the study, after the yoga intervention, that is, at T0 and T1 time points.
The Pulmonary Function Test (PFT) was conducted with a spirometry instrument (UNI-EM spiromin, Universal Medical Instruments, Delhi, India) according to standard operating procedures. Participants’ age was ascertained using their ID card. The height and weight of all participants were taken at the time of the test. To perform PFT, each participant was provided with a fresh, one-time-use mouthpiece for blowing air into the handheld spirometer. Participants were instructed about the steps and procedures and were also shown the demonstration of all the tests before conducting the actual test on them.
A 5 ml sample of venous blood was withdrawn by a trained phlebotomist at T0 and T1 time points. The blood samples were kept under refrigeration during transportation to the laboratory and processed within 30 min of withdrawal. After 10 min of centrifugation, the blood serum was separated. sIL-2R was measured at T0 and T1 on an ELISA plate reader (Bio-Rad 680, Bio-Rad PW 40, USA) using Diaclone (France) enzyme immunoassay kit where the sensitivity limit was 32.5 pg/ml. The intra-assay coefficient of variation for sIL-2R was 4.5%.
Data analysis
The data analysis was performed in R software using descriptive methods, paired t-tests, independent sample t-tests, ANCOVA, and one-tailed t-tests to find the directionality. The results have been presented in the form of mean value ± SD.
RESULTS
The anthropometric variables of the study volunteers are shown in Table 2, while the within-group comparison is given in Table 3, and between the group, the comparison is presented in Table 4.
Table 2.
Anthropometric parameters
| Parameters | Experimental group | Control group | ||
|---|---|---|---|---|
|
| ||||
| Pre (T0) | Post (T1) | Pre (T0) | Post (T1) | |
| Age (years) | 40.73 (±6.80) | 35.00 (±11.08) | ||
| Height (cm) | 165.14 (±5.46) | 165.80 (±5.47) | ||
| Weight (Kg) | 62.64 (±9.85) | 62.18 (±9.18) | 58.47 (±13.17) | 60.27 (±12.65) |
| BMI (Kg/m2) | 23.04 (±3.89) | 22.85 (±3.59) | 21.21 (±4.50) | 21.89 (±4.42) |
Table 3.
Within-group results of study variable at baseline (T0) and post-yoga intervention (T1)
| Measures | Experimental group | Control group | ||||
|---|---|---|---|---|---|---|
|
|
|
|||||
| Pre (T0) | Post | P | Pre | Post | P | |
| FVC (L/s) | 1.76 (±0.44) | 2.27 (±0.46) | 0.0000017 | 2.13 (±0.65) | 1.79 (±0.65) | 0.050 |
| FEV1 (L/s) | 1.40 (±0.46) | 1.92 (±0.41) | 0.00000001 | 1.76 (±0.48) | 1.51 (±0.56) | 0.170 |
| PEFR (L/s) | 4.91 (±2.01) | 6.24 (±2.12) | 0.00131 | 5.59 (±1.73) | 4.31 (±1.71) | 0.046 |
| sIL-2R (pg/ml) | 3052.67 (±370.93) | 2868.76 (±364.82) | 0.00000015 | 3039.57 (±196.46) | 3118.17 (±118.31) | 0.104 |
FVC=forced vital capacity, FEV1=forced expiratory volume in the first second, PEFR=peak expiratory flow rate, sIL-2R=soluble interleukin-2 receptor
Table 4.
Values of study variable at baseline (T0) and post-yoga intervention (T1)
| Measures | T0 (Pretest) | T1 (Posttest) | ||||
|---|---|---|---|---|---|---|
|
|
|
|||||
| Experimental group | Control group | P | Experimental group | Control group | P | |
| FVC (L/s) | 1.76 (±0.44) | 2.13 (±0.65) | 0.043 | 2.27 (±0.46) | 1.79 (±0.65) | 0.013 |
| FEV1 (L/s) | 1.40 (±0.46) | 1.76 (±0.48) | 0.0318 | 1.92 (±0.41) | 1.51 (±0.56) | 0.016 |
| PEFR (L/s) | 4.91 (±2.01) | 5.59 (±1.73) | 0.296 | 6.24 (±2.12) | 4.31 (±1.71) | 0.006 |
| sIL-2R (pg/ml) | 3052.67 (±370.93) | 3039.57 (±196.46) | 0.901 | 2868.76 (±364.82) | 3118.17 (±118.31) | 0.015 |
FVC=forced vital capacity, FEV1=forced expiratory volume in the first second, PEFR=peak expiratory flow rate, sIL-2R=soluble interleukin-2 receptor
While looking at the anthropometric parameters [Table 2], in the experimental group, the average body weight and BMI of the study participants showed a trend of reduction and maintenance when compared with baseline readings, whereas the control group showed an increase in the average body weight and BMI of the study participants, at the end of the study.
As shown in Table 3, at the end of the yoga intervention (T1), the experimental group showed a significant increase in the values of forced vital capacity (FVC; t (21) = −5.549, P = 0.0000017), forced expiratory volume in the first second (FEV1; t (21) = −7.90, P = 0.00000001) and peak expiratory flow rate (PEFR) (t (21) = −3.704, P = 0.00131). However, there was a significant decrease in the levels of sIL-2R (t (21) = 6.622, P < 0.00000015) at the end of the yoga intervention.
In contrast, the control group showed a significant decrease in the values of FVC (t (14) = 2.140, P = 0.050) and PEFR (t (14) = 2.189, P = 0.046) from T0 to T1. The FEV1 (t (14) = 1.445, P = 0.170) and sIL-2R (t (14) = −1.74, P = 0.104) values did not differ significantly from the baseline, but sIL-2R values showed an increasing trend from T0 to T1.
The between-group results at the baseline, as shown in Table 4, revealed that there is no significant difference in the baseline parameters of the study groups pertaining to PEFR and sIL-2R, but there was a significant difference in the FVC (P = 0.043), and FEV1 (P = 0.0318) mean values.
The between group results at the end of the study showed that the yoga group had significantly improved the pulmonary function by means of a significant increase in the levels of FVC (t (35) = 2.62, P = 0.013), FEV1 (t (35) = 2.54, P = 0.016) and PEFR (t (32) = 2.92, P = 0.006) when compared with the control group. Pertaining to the levels of sIL-2R, there was a significant reduction (t (35) = −2.548, P = 0.015) in the yoga group compared to the control group.
When the data were further subjected to one-tailed t-test analysis in the experimental group, it was found that the parameters of the lung functions were improved significantly. FVC (P = 0.00000083), FEV1 (P = 0.000000005), and PEFR (P = 0.00132) increased significantly at the end of the study. The values of sIL-2R (P = 0.000000074) were decreased significantly at the T1 time point. Combining the results of two-tailed and one-tailed t-tests proves directionality. These results show that the changes in the post-test results in the experimental group are due to yoga intervention.
DISCUSSION
In the experimental group, within-group comparison showed marked improvement in FVC, FEV1, and PEFR. Previous studies support these findings.[22,23] The wait-listed control group showed a significant reduction in FVC, FEV1, and PEFR. These results are also in line with the previous studies where no treatment has been offered to the study individuals exposed to air pollutants.[24,25] Both groups were working in the same industry for 9–10 h a day and were not taking precautionary measures advised by the authorities. The control group showed significant elevation in sIL-2R values at T1. On the contrary, the experimental group showed a significant reduction in sIL-2R values, which is in line with previous studies where pro-inflammatory cytokines have reduced post-yoga intervention.[18,26,27]
In the between-group comparison of the post-intervention results, it was observed that the FVC, FEV1, and PEFR values were improved in the experimental group. The experimental group’s findings are consistent with earlier research studies.[28,29,30] When comparing the control group results of the previous studies, we observed no significant change in the FVC, FEV1, and PEFR values unlike that of the control group of the current study. In fact, there was a significant reduction in the selected lung function parameters of the control group participants. This might be because the study participants were working in the polluted area for 9–10 h and residing in close proximity to their workplace.[24,25,31] Also, they were not given any treatment regimen, unlike that of the experimental group participants. The results in the experimental group indicate significant improvement in the lung function of experimental group participants post-yoga intervention and significantly decreased lung function in control group participants, who were waitlisted and asked to perform their regular activities as usual for the study period. The lack of precautionary measures contributed to the deteriorated lung function in the control group.
Furthermore, previous studies also proved that stress affects lung function, and the present study involved the confounding element of financial and work-load related stress.[32,33] In the experimental group, selected kriyas in the yoga module have improved lung capacity due to their cleansing properties, thus improving the PFT. Similarly, Pranayama and meditation have taken care of stress and calmed down a person. The overall effect of this yoga module resulted in improvement in the PFT of the experimental group, which was not seen in the control group as they continued to work in polluted areas and were not taking any precautionary measures. When these results of the present study were compared with the previous studies,[23,34,35,36] it was seen that the previous studies support the results obtained in the experimental group of the current study.
The predictive values of FVC (3.813 l) and FEV1 (3.181 l)[37] for selected male participants are far more than the observed values in the experimental, as well as in the control group, indicating that the lungs are definitely affected due to industrial pollutants inhaled by them. After yoga practices, the FVC, FEV1, and PEFR have improved by 22.53%, 27.08%, and 21.69%, respectively, showing significant improvement in lung capacity, while in the case of the control group, it has deteriorated by 15.96%, 14.2%, and 22.9% respectively. This explains that the yoga practices have improved the lung capacity in the experimental group, unlike the results from the control group, where actually the deterioration was seen in lung function.
There are no direct studies on the effect of ambient air pollution on levels of sIL-2R levels. Past studies showed that exposure to ambient air pollution results in the activation of pulmonary T-cells[38] and thereby might cause an elevation in the sIL-2R levels.[39] Similarly, there is no direct evidence found concerning ambient air pollution sIL-2R and yoga intervention. Still, there are studies that have shown that short-term yoga intervention helps to reduce pro-inflammation;[18,26,27,40] thereby, these studies support the reduction in the level of sIL-2R in experimental group post-study intervention. In the previous studies, it was observed that there was an increase in inflammatory cytokines due to exposure to the pollutants.[3,41] Hence, these studies support the elevation in sIL-2R values in the control group at T1. The marked benefits in the experimental group, relating to the study parameters, indicate the efficacy of yoga practices in safeguarding oneself from the harmful effects of air pollution. It is also seen that there is an inverse correlation between FEV1 values and sIL-2R.[39] All these studies support the findings of the current study. There are no studies on yogic intervention for preventing the adverse effects of ambient air pollution in relation to sIL-2R. The normal level of sIL-2R is 2500 pg/ml.[42] However, in the experimental group of the present study, it was observed that sIL-2R levels decreased at the end of the intervention (T1) but not reached normal levels. Yet, there was an improvement in lung function in the experimental group participants. In the control group, participants’ sIL-2R levels were elevated with a fall in lung function at the end of the study period (T1). The results of the present study indicate that sIL-2R levels are directly proportional to exposure to ambient air pollution, and there is an inverse relation between sIL-2R and lung functions.
The asanas selected in the present module included forward bending, lateral bending, and twisting asanas, thus expanding the chest in all directions. These asanas also give strength and flexibility to the bones and muscles of the respiratory system. Generally, individuals, while sitting, bend a little forward, which compresses the chest. This automatically develops a habit of shallow breathing. On the contrary, yoga practitioners develop a habit of erect sitting that results in slow and deep breathing, which is considered to be a healthy pattern of breathing.
The slow and deep breathing pattern adopted during pranayama improves the tone of the smooth muscles of the bronchi. It also helps to improve vagal tone, which plays a vital role in increasing ciliary action; thereby, regular practice of pranayama helps the cleansing mechanism of the respiratory tract. The participants of the current study were working and living in a polluted area that had a deleterious air content like particulate matter-10 (PM10), particulate matter-2.5 (PM2.5), nitrogen oxides, O3, CO, CO2, etc., that affects lung function. This air remains in the form of residual and reserved expiratory air if the individual is a shallow breather, as the exchange of air does not happen fully. If individual practices Kapalabhati, the toxins in the alveolar air are expelled with a forceful exhalation. Past research studies have also shown that Kapalabhati Kriya will help a person to change the breathing pattern from shallow breathing to slow and deep breathing.[43,44] Bhramari pranayama enhances the production of nasal nitric oxide that causes vasodilation of alveoli, thereby reducing pulmonary hypertension and facilitates easy breathing. Nitric oxide also has antimicrobial properties and minimizes upper respiratory tract infections. Kriyas and pranayamas help regular cleansing of the upper respiratory tract by expelling pollutants, allergens, irritants, etc., This reduces the accumulation of foreign particles in the alveolar passage, possibly resulting in lowering the production of sIL-2R and other pro-inflammatory cytokines.
FVC is the measure of overall air in the lungs, so improvement in FVC is definitely indicative of improved lung capacity, while FEV1 is a good indicator of the range of obstructive lung disease in any given individual.[45,46] Improvement in the FEV1 values indicates that the obstructive factors have reduced. Overall, improvement in FVC, FEV1, and PEFR indicates the improved efficiency of the lungs.
Kriya yoga, pranayama, and meditation have caused a positive parasympathetic shift that helps to maintain the homeostasis and normal functioning of all the organs, keeping one healthy, which might have helped to induce a sense of well-being in the participants.[47,48,49]
In the present study, the effect of selected yoga practices on people working and living near industrial areas has been studied. Both outdoor and indoor pollutants have many hazardous effects on human health, leading to an increase in morbidity and mortality.[36] The different yogic practices performed by the experimental group helped them to cleanse and relax the respiratory tract, at the same time improving lung function. On the contrary, the control group showed a fall in the said parameters of lung function and an increase in the levels of sIL-2R. This shows that the control group did not have any fallback mechanism to sustain or save themselves from the harmful effects of exposure to ambient air pollution. Thus, the results plausibly indicate the efficacy of yoga practices in combating the hazardous effects of ambient air pollution.
The present study agrees with past research studies and supports the efficacy of yoga practices in promoting health. The study revealed that ambient air pollution has adverse effects on the population working and residing in the polluted area. Regular yoga practice minimizes a load of pollutants (foreign particles) and microorganisms, thereby reducing the chances of upper respiratory tract infections. Decreased sIL-2R values confirm the reduction in inflammation, thus improving immunity. It also improves the efficacy of the lungs and can be used as a preventive tool for people living and working in polluted areas.
Limitations of the study
Although many other biomarkers are available to understand the effects of pollution, other parameters have not been studied due to limited financial resources. As this was a pilot study, we could register a limited number of participants. The study was also limited to the residents of Nangargaon Industrial Estate in Lonavla.
CONCLUSION
The results of this study may be helpful for industrial workers to follow the health security measures as per the need of that industry and also to add a yoga module daily to keep themselves free from lung disease and thus help reduce the morbidity and mortality due to industrial hazards and contribute to the national economy in the process.
The current study has suggested that even a short-term yoga practice can be beneficial in improving pulmonary functions. This emphasizes the need for yoga for people spending more hours in polluted areas, like traffic police, industrial workers, and people living in metro cities.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published, and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Kaivalyadhama SMYM Samiti (Kaivalyadhama Yoga Institute), K.R.T. Arts, B.H. Commerce & A.M. Science College.
Conflicts of interest
There are no conflicts of interest.
Acknowledgement
The authors are thankful to the Lonavala Industrial Co-operative Estate Ltd and all participants for their cooperation. The authors would like to express their sincere gratitude to Shri O.P. Tiwari (Chairman) and Shri Subodh Tiwari for their continued support and encouragement. The authors are grateful to Dr. R.S. Bhogal and the staff of the Scientific Research Dept., Kaivalyadhama, and Dr. Q.H. Ansari (Sr. Consultant Pulmonologist, Apollo Hospitals) for his technical help. They also thank Dr. Pravin Nalawade and K.R.T. Arts, B.H. Commerce & A.M. Science College.
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