A study of environmental exposure from cooking fuel use and role of intervention

Asim Saha; Sanjit Kumar Roy; Anupa Yadav; Ashit Kumar Mukherjee

doi:10.4103/ed.ed_13_18

ORIGINAL ARTICLE

Year : 2018 | Volume : 3 | Issue : 3 | Page : 69-73

A study of environmental exposure from cooking fuel use and role of intervention

Asim Saha¹, Sanjit Kumar Roy², Anupa Yadav², Ashit Kumar Mukherjee²
¹ Department of Occupational Medicine, Regional Occupational Health Centre (Eastern), Salt Lake, Kolkata, India
² Department of Environmental Hygiene, Regional Occupational Health Centre (Eastern), Salt Lake, Kolkata, India

Date of Submission	27-Jul-2018
Date of Acceptance	26-Aug-2018
Date of Web Publication	18-Oct-2018

Correspondence Address:
Dr. Asim Saha
Department of Occupational Medicine, Regional Occupational Health Centre (Eastern), Block - DP, Sector - V, Salt Lake, Kolkata - 700 091
India

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/ed.ed_13_18

Abstract

Background: Combustion of traditional biomass fuels and coal has been found to be associated with exposure to particulates and volatile organic compounds (VOCs) and cause a series of adverse health effects. Characterization-quantification of such exposure achieved so far is not optimum, and establishment of a protective mechanism with proven efficacy is the urgent need.
Methods: The present study was planned to characterize exposure from fuel during cooking in a village of India and understand the effect of using intervention measure. In this study, exposure to different pollutants was examined by personal monitoring in different cooking arrangements with traditional and modified oven.
Results: It is observed that level of the pollutants has lessened by several folds while cooking with modified oven in comparison to unmodified oven. Such change of pollutants levels with the use of modified oven was found to be statistically significant in cases of benzene (P < 0.001), toluene (P < 0.01), and particulates (P < 0.0001).
Conclusions: This study highlights the exposure from indoor air pollution during cooking and promotes use of low-cost protective mechanisms to curb resulting human health adversities. This study also calls for concerted awareness generation activity among the rural population (especially women) regarding adverse health effect of cooking fuels and protective effect of installed mechanisms.

Keywords: Cooking fuel, modified oven, particulates, personal monitoring, volatile organic compounds

How to cite this article:
Saha A, Roy SK, Yadav A, Mukherjee AK. A study of environmental exposure from cooking fuel use and role of intervention. Environ Dis 2018;3:69-73

How to cite this URL:
Saha A, Roy SK, Yadav A, Mukherjee AK. A study of environmental exposure from cooking fuel use and role of intervention. Environ Dis [serial online] 2018 [cited 2023 Jun 3];3:69-73. Available from: http://www.environmentmed.org/text.asp?2018/3/3/69/243629

Introduction

Use of biomass and coal has remained a public health concern and has affected mainly poor women and children.^[1] Combustion of traditional biomass fuels (wood, charcoal, animal dung, and crop wastes) and coal has been found to be associated with respiratory problems,^[2],[3] ocular problems,^[4] and neonatal health abnormalities.^[5] Association of tuberculosis with such fuel use has also been a concern.^[6] The health effects caused by these fuel exposures are due to the presence of incomplete combustion products of biomass fuels, such as suspended particulate matter, carbon monoxide, polyaromatic hydrocarbons, formaldehyde, and volatile organic compounds (VOCs).^[7],[8]

Studies undertaken to characterize such exposures have been few. Significantly higher concentration of dust particles and VOCs (such as benzene, toluene, and xylene) was found in kitchen using biomass fuel.^[9],[10] In developing countries, majority of households are using biomass fuel for cooking purposes resulting in substantial emission of PM₁₀, which ranges 300–3000 μg/m³ during cooking process.^[2],[11] A study carried out in Bangladesh ^[12] for monitoring of indoor air Particulate Matter of size upto 10 μm (PM₁₀) emission due to biomass burning reported concentration of 600 μg/m³. A similar study undertaken in 400 households of China monitored and found that pollutant level exceed China's Indoor Air Quality Standards.^[13] As far as Indian context is concerned, only few studies have evaluated such exposures. A study on quantifying exposures to respiratory particulate matter found concentrations of particulate matter ranging from 500 to 2000 μg/m³ during cooking in biomass using households. Average 24-h exposures ranged from 82 ± 39 mg/m³ for those using clean fuels to 231 ± 109 mg/m³ for those who used biomass fuel for cooking.^[14] Another study in Nepal ^[15] found mean concentration of PM_2.5 for improved cooking stove to be 825.4 μg/m³ and for traditional cooking stove to be 1336 μg/m³. A study made efforts to monitor VOCs emission in rural area of Delhi–NCR. The study results showed that VOCs' concentration ranged from 1.2 to 2.8 ppm during burning of biomass fuel in cooking process.^[16]

It is easily understood that remedy to such exposure and resulting health effects lie in the establishment of effective control measures. Hence, it is also important to evaluate the efficiency of such control devices. Evaluating the efficiency of such devices not only enables us to find a proper useful device for the purpose but also makes the scientific background to popularize such devices for betterment of human health. A study showed that reduction in wood smoke exposure by the use of improved chimney stove resulted in lowering of systolic blood pressure by 3.7 mmHg (95% confidence interval [CI]: 8.1, 0.6) and diastolic blood pressure by 3.0 mmHg (95% CI: 5.7, 0.4).^[17] Another study reported reduction in ST-segment depression (odds ratio 0.26, 95% CI: 0.08, 0.90) on electrocardiogram after stove intervention.^[18] A study effort designed a stove that reduced the emission of total suspended particulate matter emission by 76.1%.^[19] Although these evidences are more tentative and based on fewer studies, finding a suitable and effective intervention in this respect will have enormous effects on the health of millions of poor women and children. A need is felt for more studies to address these issues, clarify beneficial connections, and identify effective approaches to reduce the burden of morbidity. In this backdrop, the present study was planned to characterize the exposure from fuel during cooking in a rural village of India and also to understand the effect of using a model of already available intervention measure.

Materials and Methods

This present study was carried out in a village of Eastern India where exposure to different pollutants was examined in different cooking arrangements by personal monitoring. In the effort to examine the efficacy of intervention measures to reduce the exposure of women and children in village households from cooking smoke (particulate matter, VOCs), we tried to provide a low-cost modified structure of ovens (wood using ovens and coal-animal dung using ovens) to some households of a village. We could find some earlier efforts of modifications by different agencies (not in popular use due mostly to lack of awareness). The modification consisted of a wide-based oven with an “L”-shaped arrangement of pipe for diverting out the smokes. The base of such oven was dug in the mud floor, and only upper part was over the floor level. The smaller hand of “L” was connected with oven just below the floor level, whereas the larger hand was carrying smokes through the roof and discharging in the exterior above. The difference between wood-using ovens and coal-animal dung-using ovens was the provision of a metal mesh in case of coal-animal dung-using ovens to enable the oven to hold the fuels. We made some awareness improvisations and installed the modified low-cost structure, and we expected that exposure will be reduced considerably using this structure. We obtained values of exposure (particulate matter, VOCs) in these households before such modifications of ovens and after such modifications of ovens to examine efficacy.

Personal sampling of particulate matter in cooking areas was done gravimetrically with personal sampling technique. A low-volume personal sampler (SKC Inc., USA) was used for sampling purpose; samples were collected on glass fiber filter paper fitted in a cyclone head and attached near the breathing zone of women subjects during cooking period. Before and after sample collection, filter papers were conditioned in desiccators for 24 h. Sampling was done at a flow rate of 2 l per min for 8 h. Collected samples were carried to laboratory carefully. Personal monitoring of VOCs was also done with a low-volume sampler (SKC Inc., USA) fitted with a charcoal sorbent tubes (size 6 mm × 70 mm), packed with activated charcoal (60–80 mesh) in two compartments (100/50 mg). The sorbent tube holder was connected to a constant flow pump, attached near the breathing zone of women subjects during cooking period, and air was drawn at the rate of 100 ml/min for a period for 3–4 h. The flow rate was calibrated regularly using an airflow calibrator (Ultra Flow, SKC, USA). Collected samples were labeled, sealed, and carried to the laboratory in proper way. Storage of all the samples was done in fridge till analysis in gas chromatography-flame ionization detector (GC-FID).

Gravimetric weight difference was used for the measurement of particulate matter. Filter papers were weighed before and after sampling, and the amount of the sampled particulate matter was measured as the gain in sample mass.^[20] Filter paper which was used for sampling purposes were handled in dust and moisture-free room at 20°C ± 1°C temperature. Particulate matter concentration was assessed using the volume of sampled air drawn and expressed in mg/m³. VOCs (benzene, toluene, ethylbenzene, xylenes, propylbenzene, and mesitylene) were sampled in the charcoal sorbent tubes, collected samples were desorbed in 1 ml carbon disulfide (CS2) for 1–2 h, analysis was done with GC-FID (Auto System XL GC, Perkin Elmer), and capillary column, PE 624 (Perkin Elmer) of length 30 m, i.d. 0.53 mm, was used. The standard chromatographic conditions for analysis was maintained (isothermal at 100°C; injector temperature at 200°C; detector temperature at 180°C).^[21]

Results

In this study, we assessed the exposure of people to VOCs and particulate matter while cooking. Exposure was assessed by personal monitoring with women volunteers (40 healthy women aged 35–45 years participated in this study) during cooking activity. This study gave us an indication of exposure pattern in respect to different fuels. All women participated with unmodified oven while 20 of them participated in experimentation with modified oven also. Ten personal air samples were collected and analyzed for each type of fuel exposure, and mean as well as standard deviation values were calculated in respect to all pollutants. A total of 40 samples in respect to unmodified oven and 20 samples in relation to modified oven were analyzed (grand total of 60 samples). Benzene exposure was highest in use of coal (351.76 ± 197.23 μg/m³), while propylbenzene exposure was highest during use of wood (69.40 ± 74.33 μg/m³). Toluene exposure was again highest in coal use, whereas ethylbenzene exposure was highest in kerosene oil use. Similarly, coal use produced highest m, p-xylene exposure and kerosene produced the highest level of o-xylene exposure. Liquefied petroleum gas (LPG) use showed least harm in case of all the pollutants except mesitylene, which had the highest exposure level (148.79 ± 69.05 μg/m³) during LPG use. Particulate exposure was also highest in coal use (3.23 ± 0.7 mg/m³) followed by wood use (1.96 ± 0.68 mg/m³) and kerosene use (1.07 ± 0.46 mg/m³) [Table 1].

Table 1: Exposure of women to different pollutants from unmodified and modified oven while cooking with different types of fuels

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[Table 1] also shows the exposure of female subjects to different pollutants during cooking with various types of fuels using modified oven. It is observed that the level of the pollutants has lessened by several folds while cooking with modified oven in comparison to unmodified oven. Mean benzene exposure in coal use has lessened from 351.76 to 45.71 μg/m³. Same exposure in wood use has lessened from 302.34 to 41.19 μg/m³. Mean toluene exposure in coal use has lessened from 328.62 to 60.68 μg/m³ and mean toluene exposure in wood use has lessened from 274.98 to 44.23 μg/m³. Mean particulate exposure in coal use has lessened from 3.23 to 0.69 mg/m³ and mean particulate exposure in wood use has lessened from 1.96 to 0.52 mg/m³. Such change of pollutants levels with the use of modified oven was found to be statistically significant in cases of benzene (P < 0.001), toluene (P < 0.01), and particulates (P < 0.0001). The same trend of decreasing values of pollutants was observed (though statistically nonsignificant) regarding exposure to ethylbenzene, m, p-xylene, o-xylene, propylbenzene, and mesitylene in case of both coal and wood use while experiencing with modified oven. Efficacy percentage of modified oven was calculated as ([pollutant concentration of unmodified oven – pollutant concentration of modified oven]/pollutant concentration of unmodified oven) × 100% and shown in [Table 2]. Efficacy levels in relation to prominent pollutants such as benzene, toluene, and particulates were encouraging.

Table 2: Efficacy of modified oven in reducing level of pollutants in relation to coal and wood use

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Discussion

In developing countries, significant number of population is using biomass fuels resulting in substantial emission of pollutants.^[11] Exposure to higher concentration of dust particles and VOCs is the main concern.^[10] Such exposures are thought to be the cause of adverse findings related to human health.^[8] Lessening such exposures through a suitable intervention measure is expected to reduce morbidity burden considerably. However, characterization-quantification of such exposure achieved to date is far from optimum, and establishment of a protective mechanism with proven efficacy is the need of the day. This study has not only highlighted pollution at household level during cooking by quantifying the exposure of benzene, toluene, and particulates, but this study has also made one of the pioneering efforts to measure the exposures of ethylbenzene, m, p-xylene, o-xylene, propylbenzene, and mesitylene during cooking activities. The value of different VOCs and particulates was found to be more than threshold limit values (TLVs) in many occasions. The TLVs of benzene, toluene, ethylbenzene, xylene, and mesitylene are 0.5, 50.0, 100.0, 100.0, and 25.0 ppm, respectively.^[22] The recommended limit for respiratory particulates ^[22] is 3 mg/m³. While calculating the values in ppm units to examine with TLV values, it was found that mean benzene exposure in coal use has lessened from 0.11 to 0.01 ppm and in case of wood use has lessened from 0.09 ppm to 0.01 ppm. The installed device has significantly reduced the emission; the reduced values are well below TLV values. Mean toluene exposure has lessened below TLV values in coal as well as wood use after using the modified oven (value reduced from 0.08 to 0.01 ppm in coal use and from 0.07 to 0.01 ppm in wood use). Calculated efficacy levels in relation to some important pollutants were high. These findings signify the necessity of installation of efficient devices.

The strength of this study lies in the fact that this study assessed real-time population-based exposure from indoor air pollution during cooking with various fuels and promoted the use of low-cost protective mechanisms by scientifically establishing its efficacy. However, the study had some limitation also. Assessment of such exposure and efficacy in different geographical locations with different subjects and also involving seasonal variations could have made the findings of this study more valid and generalizable.

Conclusion

This study assessed the efficacy of an already available protective mechanism to reduce indoor air pollution and found it to be efficient (especially in reducing the exposure levels of benzene, toluene, and particulates) which emphasizes the fact that establishment of such a device can very effectively benefit rural women and children. In the course of this study, it was observed that lack of awareness about the possible benefits of the system and lack of knowledge to establishing and maintaining such system were the principal factors for nonuse of similar devices. This study highlights the exposure from indoor air pollution during cooking and promotes the use of low-cost-protective mechanisms to curb resulting human health adversities. This study also calls for concerted awareness generation activity among the rural population (especially women) regarding adverse health effect of cooking fuels and protective effect of installed mechanisms. Provision of knowledge and facilities for installing such mechanisms in rural households is the key not only in reducing morbidity burden but also in reaching public health benefits to every poor rural household.

Financial support and sponsorship

This study was carried out with the intramural support of the institute.

Conflicts of interest

There are no conflicts of interest.

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