Indian Journal of Allergy, Asthma and Immunology

: 2019  |  Volume : 33  |  Issue : 2  |  Page : 79--85

A study to compare pulmonary function in apparently healthy females exposed to biomass fuel combustion versus clean fuel combustion in Allahabad District

Tariq Mahmood, Ashish Kumar Jain, Arvind Kumar Verma, Pundarik Dwivedi 
 Department of Pulmonary Medicine, MLN Medical College, Prayagraj, Uttar Pradesh, India

Correspondence Address:
Dr. Tariq Mahmood
Department of Pulmonary Medicine, L-6, MLN Medical College Campus, Lowther Road, Prayagraj, Uttar Pradesh


BACKGROUND: Life in a typical Indian household revolves around the cooking area, and Indian women spend much of their time there. Cooking stoves in biomass fuel users are nothing more than a pit, a chulha, or three pieces of brick. Cooking under these conditions entails high levels of exposure to cooking smoke. AIMS AND OBJECTIVES: (1) To compare the pulmonary function parameters of biomass fuel users with clean fuel users. (2) To evaluate the pulmonary function test (PFT) among individuals exposed to biomass fuel combustion. MATERIALS AND METHODS: Three hundred and fourteen nonsmoking women without any history of any major chronic illness in the past were selected for this study. The study group comprised of 68 women exposed to biomass fuel combustion, 105 women exposed to clean fuel combustion, and 141 women exposed to mixed fuel (earlier using biomass fuel but now gradually shifting to clean fuel). All women were evaluated for PFTs MIR spirolab III. OBSERVATION AND RESULTS: The lung function parameters were significantly lower in the women exposed to biomass fuel in comparison to the clean fuel users and mixed fuel users forced expiratory volume 1 (FEV1) (P < 0.05); FEV1/forced vital capacity (FVC) (P < 0.05); FVC (P < 0.05); peak expiratory flow rate (PEFR) (P < 0.05); the lung function parameters were also significantly reduced in group of mixed fuel users in comparison to the group of clean fuel users FEV1 (P < 0.05); FEV1/FVC (P < 0.05); FVC (P < 0.05); PEFR (P < 0.05). The evaluation of PFTs suggested the increased risk to the obstructive type of pulmonary disease in biomass users. CONCLUSION: The reduction in the pulmonary function in the biomass-exposed women could be due to high exposure to biomass pollutants with inadequate ventilation in cooking area.

How to cite this article:
Mahmood T, Jain AK, Verma AK, Dwivedi P. A study to compare pulmonary function in apparently healthy females exposed to biomass fuel combustion versus clean fuel combustion in Allahabad District.Indian J Allergy Asthma Immunol 2019;33:79-85

How to cite this URL:
Mahmood T, Jain AK, Verma AK, Dwivedi P. A study to compare pulmonary function in apparently healthy females exposed to biomass fuel combustion versus clean fuel combustion in Allahabad District. Indian J Allergy Asthma Immunol [serial online] 2019 [cited 2020 May 31 ];33:79-85
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Full Text


Air pollution has been commonly perceived as an urban problem associated with motor vehicles and industries. However, in developing countries, air pollution tends to be highest indoors where biomass fuels are burned by many households for cooking and space heating.[1],[2]

There are wide variations between rural and urban households regarding the specific type of biomass fuel used. In rural India, 62% of households use firewood and 14% cook with dung cakes while 13% use straw, shrubs, grass, and agricultural crop residues. In urban India, 22% use firewood, 8% use kerosene, and the rest uses cleaner fuels like liquefied petroleum gas (LPG) or natural gas.[3] Seventy-five percent of rural households reported firewood as their primary cooking fuel as compared to only 22% of urban households.[4]

LPG is commonly used as an indicator of a clean fuel using household. The use of LPG (or other gaseous fuels), which is known to result in the lowest pollution levels within households, remains a nonfeasible proposition for bulk of India's population as a result of prices, limited supply, and access.[5]

Biofuel combustion is associated with the release of increased amounts of pollutants such as sulfur dioxide, nitrogen dioxide, carbon monoxide, total suspended particles, and polyaromatic hydrocarbons.[6],[7] The emission factors for these pollutants from biofuels far exceed those from other commercial fuels such as LPG and kerosene. The emission factor for total suspended particles is about 20 times higher for biofuels then for LPG. The concentration of indoor pollutants is significantly higher in kitchens using biofuels compared to those using other fuels.[8]

Respiratory diseases occurring in adults primarily in rural women exposed to biomass combustion are interstitial lung disease, chronic obstructive pulmonary disease (COPD), tuberculosis, and lung cancer.[9] Studies both in India and other countries have confirmed a decline in lung function parameters [10],[11],[12],[13],[14],[15],[16],[17],[18] and high morbidity and mortality in biomass fuel users.[19],[20]

 Materials and Methods

Institutional ethics committee permission was procured prior to the start of the study. This is an observational cross-sectional study comparing the pulmonary function of apparently healthy females, exposed to biomass fuel smoke (chulha) versus those exposed to clean fuel combustion in Allahabad district conducted over period from August 2017 to July 2018. Total 314 women between 30 and 60 years accompanying the patient attending pulmonary medicine outpatient department, Swarooprani Nehru Hospital, Allahabad on Tuesday and Saturday were randomly selected for study. All women between 30 and 60 years were enrolled in this study as per inclusion and exclusion criteria.

Inclusion criteria

Females between 30 and 60 years of ageFemales having 10 years or more than 10 years of exposure to chulha smoke (using biomass fuel wood, cowdung or farm produce) or LPG smoke.

Exclusion criteria

Females having <10 years of exposure to chulha smokeFemales with respiratory problems and on treatmentAny prolonged medicationsAny chronic or morbid illnessSmokersPregnancy.

Study protocol

After obtaining written informed consent, individuals qualifying inclusion criteria were assessed as follows:

Recording of demographic dataIndividuals were subjected to a set of questions for determining the history of previous exposure to biofuels or LPG.


Individuals were investigated for the following parameters:

Forced expiratory volume 1 (FEV1)Forced vital capacity (FVC)FEV1/FVC ratioPeak expiratory flow rate (PEFR).

Pulmonary function tests (PFTs) were performed using computerized spirometer, Medical international research (MIR) spirolab III. Initially, the individuals were made to sit comfortably and breathe in and out normally to familiarize themselves with the equipment. The individuals were then asked to inhale to their maximum capacity and then forcefully blow out into the sensor (nose clipped) as hard as and for as long as possible. This procedure was repeated, and the best of three readings were considered for analysis. The parameters measured were FVC, FEV1, PEFR.

Statistical analysis

Statistical analysis was done with SPSS (Lucknow, Uttarpradesh, India), Excel-2013. T-test was used for calculating P value and linear regression for means were used to see relationship between biomass fuel users, clean fuel users and mixed fuel users. P< 0.05 was considered as statistically significant.

 Results and Observation

Of 404 women initially recruited, 68 women were using biomass fuel, 105 were using clean fuel, and 141 women used mixed fuel (earlier used biomass fuel, but now gradually transforming to clean fuel, may be due to increasing availability of clean fuel in rural society). Data from remaining 90 women were not included because:

36 women refused pulmonary function testing17 women were <30 years of age22 women were more than 60 years of age7 women were known case of posttubercular obstructive airway disease2 women had recent myocardial infarction within 1 month6 women were unable to perform pulmonary function testing.

A total of 314 women were included in the study during the period from August 2017 to July 2018 as per inclusion and exclusion criteria. Women were classified on the basis of cooking fuel in to three groups biomass fuel users, clean fuel users and mixed fuel users (earlier used biomass fuel, but now gradually transforming to clean fuel, may be due to increasing availability of clean fuel in rural society).

The overall mean age in biomass fuel users was 41.41 years, mean age in clean fuel users was 36.80 years, and in mixed fuel, users was 40.08 years. The women in the three groups were similar with respect to age [Table 1].{Table 1}

Maximum number of women in all type of fuel users was in 30–40 years age group [Table 1].

Of 314 women selected for the study, 153 (48.72%) were rural dwellers and 161 (51.27%) were urban dwellers. Among the 153 rural dwellers, majority were mixed fuel users 87 (56.86%), biomass fuel users were 55 (35.94%), and 11 (7.18%) were clean fuel users. Among 161 urban dwellers, majority were clean fuel users 94 (58.38%), mixed fuel users were 54 (33.54%), and only biomass fuel users were 13 (8.07%).

From [Figure 1] and [Table 2], it can be inferred that in urban areas, predominant fuel used for cooking is clean fuel, and in rural areas, predominant fuel used for cooking is mixed fuel (earlier used biomass fuel, but now gradually transforming to clean fuel, may be due to increasing availability of clean fuel in rural society).{Figure 1}{Table 2}

Among the biomass fuel users [Figure 2] and [Table 3], women having 10–15 years of exposure were 29 (43%), 17 (25%) women had 16–20 years of exposure, 5 (7%) had 21–25 years of exposure, 10 (15%) had 26 years of exposure, and the remaining 7 (10%) had >30 years of exposure.{Figure 2}{Table 3}

Among the clean fuel users [Table 3], most of the women 60 (57%) have exposure of 10–15 years of clean fuel smoke, 20 (19%) women have exposure of 16–20 years, 12 (11%) have exposure of 21–25 years, 7 (7%) have exposure of 26–30 years, and the rest 6 (6%) have exposure to >30 years [Figure 3].{Figure 3}

Among the mixed fuel users [Table 3], most of the women 37 (26%) have exposure of 16–20 years, followed by 36 (26%) women who had exposure of 10–15 years, 27 (19%) have exposure to 21–25 years, and 22 (16%) have exposure to 26–30 years [Table 4].{Table 4}

From [Table 4], it can be inferred that most of the biomass fuel users resides in kuchcha house 39 (57.35%) while most of the clean fuel users 92 (87.61%) resides in pakka house.

[Figure 4] and [Table 5] represents the mean weight (kg), mean height (cm), and mean body mass index (BMI) (kg/m 2) among the biomass fuel users and clean fuel users [Figure 5]. After analyzing the data, there was no statistical difference (P > 0.05) between the mean weight, mean height, and mean BMI among the biomass fuel users, clean fuel users, and mixed fuel users.{Figure 4}{Table 5}{Figure 5}

The percentage of predicted value of FEV1, FVC, and PEFR were significantly lower in women using biomass fuels compared with women using clean fuels [Table 6].{Table 6}

The percentage of predicted value of FEV1, FVC, and PEFR were significantly lower in women using biomass fuels compared with women using mixed fuels [Table 7].{Table 7}

The percentage of predicted value of FEV1, FVC, and PEFR were significantly lower in women using clean fuel user compared with women using mixed fuels [Table 8].{Table 8}


In the present study, we aimed to see the effect of biomass fuel and clean fuel smoke on various respiratory parameters. In our study, rural women were more exposed to biomass fuel smoke as kuchcha houses are not provided with proper ventilation (no chimney or vent). Majority of the urban women resided in pakka houses with proper ventilation; so, the exposure to fuel smoke is less.

In this study, most of the rural women cooked in closed kitchens and were more exposed to biomass fuel smoke as compared to women who cooked in open kitchen and were less exposed. A study conducted in Porur, Chennai reported that cooks using an open outdoor kitchen had less exposure to fuel smoke than cooks using an enclosed kitchen as emissions are dispersed outdoor.[21]

In a study conducted in Nigeria on relationship between household air pollution from biomass smoke exposure and pulmonary dysfunction in rural women and children, the percentage-predicted values of pulmonary function parameters (FEV169.78 ± 16.58; FVC 78.63 ± 10.99; PEFR 58.47 ± 23.21) and FEV1/FVC ratio (74 ± 13) were significantly reduced in the biomass exposed rural women. The women included in Nigeria study were from age group 20–60 years but the quantum of exposure in years was not considered in the study.[22] In our study, the percentage predicted values (FEV175.48 ± 20.86; FVC 81.95 ± 22.04; PEFR 63.52 ± 21.51) and FEV1/FVC ratio (78.92 ± 10.83) were significantly reduced in biomass smoke exposed women. The female individuals included in our study were of age 30–60 years. The mean duration of exposure in our study was 19.95 ± 9.57 years.

In a study conducted in Karnataka, it was observed that the lung function parameters (FEV1, FVC, FEV1/FVC %, PEFR) were significantly lesser in the study group exposed to biomass fuel. The mean duration of cooking years being 12 ± 5.2 years.[23]

Another study conducted in biomass-exposed rural women of Tamil Nadu found that COPD prevalence was higher in biomass fuel users than the clean fuel users. It was further stated that COPD prevalence was much higher in women who spent more than 2 h/day in cooking and have been involved in cooking for more than 15 years.[24]

One study observed that PEFR was reduced in biomass fuel users as compared to clean fuel users.[15] In a study by Saha et al., FEV1, FEV1/FVC%, FEF 25%–75%, and PEFR values were significantly lower in females using biomass fuels than the females using LPG.[11] A Turkish study observed that mean values of PFT parameters: FEV1, FVC, and FEF 25%–75% were decreased statistically among the biomass-affected group.[25] A recent meta-analysis has shown that biomass fuel exposure is associated with a significant risk for chronic bronchitis and COPD,[26] and the strength of association is similar to that of cigarette smoking.[27] There is strong evidence linking inhalation of biomass fuel smoke and chronic bronchitis in women aged above 30 years with a relative risk of 3.2 (95% confidence interval 2.3–4.8).[19]

Studies both in India and other countries have confirmed that exposure to biomass fuels has a significant association to decline in objective lung function parameters.[10],[12],[13],[14] Population-based studies have demonstrated a clear link between exposure to smoke from biomass fuels and COPD in India,[10],[28] Colombia,[29] China,[30] Spain,[31] and Mexico.[12] Comparative analysis has demonstrated that biomass and cigarette smoke activate pathogenic processes, such as inflammation and protease expression, that are linked to the development of COPD. Biomass is found to activate mechanisms in the lung that are central to the development of COPD.[12]

Although women exposed to biofuel smoke had functional impairment compared with clean fuel users and mixed fuel users, the degree of impairment was not sufficiently large to manifest in a significant increase in symptoms. It is also possible that respiratory symptoms were not correctly reported whereas pulmonary functions (an objective parameter) could be assessed.

In our study, we found that among the biomass fuel users, majority of women were using wood+dung cake 55 (80.88%), followed by wood alone 7 (10.29%), only 5 (10.29%) women were using dung cake, only 1 (1.47%) were using wood+coal, and none of them was using coal alone.

The present study showed a significant relationship between biomass fuel combustion and decrease in lung function. This could be due to exposure to high concentration of respiratory irritants emitted during biomass fuel combustion and poor ventilation. Thus, decline in lung function in biomass fuel-exposed women can be avoided by improving adequate household ventilation, by improvement in stoves and change of the fuel type for cooking and heating.

Limitations of the study

There is a fact that practically, all women had previous exposure to biomass fuels, most of them in their childhood. This means that current clean fuel exposure could not be contrasted to “never biomass exposure,” but instead to “no recent exposure”Quantum of exposure in terms of hours/day were not taken into accountIn many developing countries, smoking by men indoors is also common, and the interactions between tobacco smoke and biomass fuel exposures may add to the health problems, but this has not been studied.


The healthy nonsmoking women using biomass fuel for cooking had sub clinical respiratory impairment, identified by PFTs, which are sensitive and simple tests to identify early respiratory impairments. Indoor pollutants liberated from incomplete biomass fuel combustion may be risk factor for pulmonary diseases like COPD.

Biomass fuel is having detrimental effect on health of human beings. Biomass fuels are used inside homes without proper ventilation. Hence, use of more advanced stoves with chimneys/vent and usage of fuels that do not produce such fumes (such as LPG) is recommended to avoid exposure of women who are practicing cooking on biomass stoves. Women in developing countries who cook over a wood stove for years and inhale the smoke can experience the same clinical characteristics, diminished quality of life and increased mortality rates as tobacco smokers. There is a need to expand the limited amount of knowledge and to create effective intervention programs with an objective to provide a better quality of life to individuals exposed to biomass smoke pollutants. Further research is recommended as very little research has been done on chronic effects of biomass smoke.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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