European Journal of Cardiovascular Medicine

Indoor air pollution(IAP) can be defined as the dust, dirt, or gases in the air inside buildings such as our home or work place that could be harmful to breathe in[1]In the last decade, indoor air quality is acquiring more attention for improving the wellbeing, comfort and health of the building occupants.[2]Location of air intakes, types of filtrations, refrigeration and heating system may reduce the quality of indoor air and increase volatile organic chemicals(VOC),formaldehyde, asbestos, freon, Chlorofluorocarbons (CFC) and radon.[3] Inmates of the home like women and children are at greater risk as most of the time they are enclosed within the home without adequate ventilation.[4] The sources of IAP include combustion of solid fuels indoor, refrigerators, heating and cooling system, perfumes and air fresheners, insecticide, pesticides, paint, tobacco smoking, dust and mites,emission from construction and furniture and improper maintenance of ventilation system. There is variation in sources of IAP in different part of world and various socioeconomic levels.[5]

The main indoor air pollutants are fine particles, carbon monoxide, polycyclic aromatic hydrocarbons, nitrogen oxides, sulphur oxides, arsenic and fluorine, volatile and semi-volatile organic compounds,aldehydes, pesticides, asbestos, lead and biological pollutants.[1]

The main symptoms of IAP are irritation of eye and throat, nasal congestion, recent memory loss, feeling of exhaustion, headache, anorexia,nausea, lack ofconcentration, wheezing with cough, chest tightness, etc. [1,6] Household air pollution exposure leads tonon-communicable diseases including stroke, ischemic heart disease, chronic obstructive pulmonary disease (COPD), chronic bronchitis, bronchial asthma, tuberculosis, cataract, low birth weight, lung cancer.[6]

Approximately 3.2million deaths per year in 2022 were attributed to IAP out which 2,37,000 deaths were children under 5years of age, 32% ischemic heart disease, 23%stroke,21% lower respiratory tract infection, 19% chronic obstructive pulmonary disease and 6% lung cancer.[7]

A community based cross-sectional study was performed in rural villages-Bollikunta, Panthini and urban areas- Rangampet of Warangal district of Telangana state. With the help of Auxiliary Nurse Midwives (ANM) and Accredited Social Health Activists (ASHA) all the houses in villages were enlisted. 16 households from each rural village were selected. 18 households of urban areas were selected by simple random sampling technique, lottery method. A total of 49 households with 186 members were visited and was interviewed about risk factors and respiratory system was assessed. Those who did not give consent, houses which were locked, uncooperative respondents, children below 12 years, severe dyspnoea, tuberculosis, recent abdominal and thoracic surgery, recent eye surgery and recent episode of heart attack and stroke were excluded from the study. Those who were on any bronchodilators for 4 hours prior to the procedure were also excluded. With portable spirometry Lung Function was evaluated. In each household Air Quality Index was also monitored using Multi-Functional Air quality detector.

Households were recruited from June 2022 to December 2022, for a duration of 7 months.Data was collected by administering a pretested and semi structured questionnaire and interview. The questionnaire consists of a) socio-demographic factors- age, sex, education, occupation, socioeconomic status classified using modified B.G.Prasad scale, type of family; b) causes of IAP- overcrowding, ventilation, type of fuel for cooking, use of incense stick for pooja, air fresheners, mosquito repellent or coils, cigarette smoking inside the house, cushioned furniture or mats filled with dust, cleanliness of house, presence of moulds or damp roof or walls, chimneys present; c)Effects of IAP- mucous membrane irritation, headache, nausea, palpitation, fever in past 15days, acute respiratory infection in past 3 months;  d) Air quality index  and e)examination of respiratory and cardiovascular system along with lung function test.

The air quality of each household was monitored using calibrated multi-functional air quality detector. After closing all the windows and doors to prevent movement of air, in the center of room the detector was used to monitor for different parameters of Air Quality like particulate matter 2.5 (PM2.5), particulate matter 10 (PM10) and carbon dioxide (CO₂).

Respiratory systemand cardiovascular system were examined clinically. Lung Function was assessed using personnel computer-based spirometry which is portable. The respondents Id, name, age, gender, weight in kilograms, height in centimetre and previous history of smoking was entered in the initial setup. The respondent were made to sit comfortably and after trail involving maximum inspiration and expiration, three measurements of lung function was recorded but highest was selected for analysis. The parameters measured are Forced Vital capacity (FVC), volume exhaled after 1 second (FEV1) and ratio of FEV1 to FVC. Both FEV1 and FVC above 80% andFEV1/FVC ratio of greater than 0.70 of the predicted value were considered normal spirometry findings^[8].

All the collected data was entered in MS Excel and exported to SPSS version 20.0. for analysis. Descriptive statistics like frequency and percentages was used to express socio-demography, air quality index and causes of IAP. Inferential statistic like Chi-square and Pearson correlation test was done to find relation between variables. A P-value of <0.05 was considered statistically significant.

ETHICAL CONSIDERATION:

Ethical clearance obatained from Institutional Ethical Committee and data was collected after obtaining informed consent in vernacular language. Confidentiality and privacy was maintained throughout the study.

A total of 186 study participants were surveyed, out of which 18 households of urban area consisting of 42 individuals and 32 household of rural area consisting of 144 individuals were surveyed. Of the 49 households surveyed, 102 (54.8%) individuals dwelled in pucca house and 84 (45.16%) in kutcha house. Regarding number of rooms 72 (38.7%) individuals lived in <2 rooms and 114 (61.29%) individuals lived in ≥2 rooms. The mean age of study population was 39.68 (±15.12) years, minimum and maximum age as 18 and 88, respectively.[Table 1]

Major contributory factors of IAP in our survey were from overcrowding (65.1%), use of incense stick (58.6%) and also use of mosquito repellents or coils (64%) which also shows strong association. Fuel used by majority of the households was liquified petroleum gas followed by biomass like wood, 63.9% and 33.4%, respectively.[Table 2 a3]

Air quality index in the surveyed house showed PM2.5 and PM10 to be predominantly present, 47.8% and 40.9%, respectively in unhealthy manner. Carbon Dioxide levels were almost equally distributed in healthy and moderate levels, 40.3% and 42.5%, respectively.[Figure 1]

IAP was present in 62.5% households and absent in (37.1%) households. FEV1, FVC and FEV1/FVC ratio were normal in 147 (79%) and absent in 39 (21%) respondents. Association between FVC and FEV1 in presence of IAP is shown in figure 2 and 3. There is also positive correlation between mucous membrane irritation, headache and acute respiratory infection in past 3 months with presence of IAP.[Table 4]

Figure 2: Box plot showing association of Forced vital capacity (FVC) in Prescence of indoor air pollution

Figure 3: Box plot showing association of Forced Expiratory volume in 1 second (FEV1) in Prescence of indoor air pollution.

There are many evidence showing increase of IAP in India and its associated health effects. Further research is required to investigate the measure of exposure levels of indoor pollutants and to further improve the evidence for their association with outcomes including Tuberculosis, cataract, asthma, COPD, cardiovascular health, pregnancies and malignancies. More public education on indoor air pollutants and their health consequences is needed. Through proper awareness about causes of indoor pollution and measures of interventions vulnerable population can be protected. Especially women should be made aware of proper housing, type of fuel,use of various products that contribute to IAP like incense stick, mosquito coils and repellents, air fresheners, etc.Building designers, who may also play a vital role in controlling IAP, can stress the importance of ventilation and housing. Constructing windows above cooking stove and institution of windows and doors for cross ventilation can improve ventilation. The Policy makerscan emphasize on providing cleaner fuels,ban on productswith harmful emissions. An excellent illustration is the one designed by the Ministry of New and Renewable Energy's National Biomass Cookstoves Initiative under a Special Project on Cookstoves during 2009-2010, with the primary goal of increasing the availability of clean and efficient energy for the country's energy-deficient and poorer sections.^[18]Current studies focus should be on improved (high-efficiency and low emissions) stoves and fuels, which provide more affordable options for the poor majority in developing countries.Thus, an hour of need has come where policy makers, politicians, researchers and public health experts can collaborate to ensure in commitment to increase awareness and reduce IAP and its sufferings.

LIMITATIONS OF STUDY:
The current study has some limitations. The study was done in a selected geographical area of a state. Air quality index was monitored for relatively short duration and instruments like PCE-RCM 05, PCE-HFX 10 and PCE-RCM would give more accurate results. Portable spirometry demonstrates airflow limitations as it is effort dependent and requires motivated respondents. Even though contributory factors for IAPwas identified causality cannot be established as it is a cross sectional study.More studies need to be done to assess the exposure levels of pollutants in households andits outcomes on health.

Effects of IAP and its predictors were assessed in 49 households in Warangal districts. 86% households had at least one cause for IAP. Though majority were literate and came from higher socioeconomic class in study population, many of them were not aware about IAP and its perceived effects. In contrast to study done by Priyadarshini et al, which showed 88.8% women were aware of IAP. ^[9] Overcrowding was present in 65.1% of the households, though cross ventilation was practiced in 55.4% households. Type of housing has strong association with presence of IAP, which is similar to study done by Khalequzzamanet al. ^[10]58.6% of respondents also used incense stick for religious rituals predominantly by Hindus for poojas. Burning of incense sticks emits air pollutants that causes inflammation to lung tissues, increases other respiratory infections and has risk for carcinomas. ^[11] Using mosquito coils or repellents in the evenings were practiced by majority respondents (64%), which is also associated with presence of IAP. Those exposed to chemicals released from the mosquito coils experience two to three times higher risk of serious ARIs than unexposed children. ^[12] Of 95 male respondents, 43 were smokers, whereas only 13 smoked cigarettes at home. Pinheiro, G.P. et al study shows that indoor smoking has dual effects, household pollution and respiratory effects like asthma. ^[13] Type of fuel used also plays an important role as contributory factor in IAP. As majority used LPG in the study population followed by biomass like locally available woods, twigs, dried leaves and wood dust. Studies have shown that women exposed to pollutants from solid cooking fuels are at greater risk for developing breast cancer, low birth weight, acute lower respiratory tract infections in children and tuberculosis in elderly who are mostly at home. ^[14,15]Cooking without a chimney can raise IAP, which can be amplified if ventilation is also lacking. Study done by Hartinger et al and Tian et al shows that chimneys can reduce the number of pollutants especially the products of incomplete combustion by solid cooking fuels. ^[16,17]

In our study, individuals exhibited lower FVC and FEV1 values in the presence of IAP. Even in absence of IAP few outliers were present due to presence of underlying respiratory condition like asthma and chronic obstructive lung disease.

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