When we talk about air pollution in India, the image that usually comes to our mind is that of smog-choked city skylines and traffic-clogged roads. Rarely do we discuss one of the most dangerous forms of air pollution because it is far less visible and even lesser understood – the polluted air inside our homes. As outdoor AQI takes over our lives, indoor air pollution is relegated to the background, silently affecting millions daily.
What causes household air pollution?
According to the World Health Organisation (WHO) household air pollution was responsible for an estimated 2.9 million deaths per year in 2021, including over 309 000 deaths of children under the age of 5.
National Centre for Disease Control (NCDC) states that household air pollution is caused majorly by burning biomass such as wood, coal, dung, kerosene in chulhas or fireplaces for cooking and heating purposes. Although access to LPG has improved in recent years, 64% of India’s population relies on solid fuel for their household cooking needs, claims Clean Cooking, an initiative to make clean cooking accessible to all.
The major sources of indoor air pollution are mosquito coils, incense sticks, cigarettes, bidis, use of sprays, solvents, and fumes from chemicals used in building interiors etc. According to a study done by the European Community Respiratory Health Survey (ECRHS), “Women cleaning at home or working as occupational cleaners had accelerated decline in lung function, suggesting that exposures related to cleaning activities may constitute a risk to long-term respiratory health.” It further noted, “Women cleaning at home and female occupational cleaners had more doctor-diagnosed asthma than women not cleaning. Furthermore, men cleaning at home had more doctor-diagnosed asthma than men not cleaning and male occupational cleaners. There was not substantially higher prevalence of spirometry-defined chronic airway obstruction in either of the exposure groups as compared with the unexposed group.”
Health practitioners believe that the air inside our homes can sometimes be 10 to 50 times more toxic than the air outside. “IAP (indoor air pollution) could be more dangerous than other viruses that cause immediate fever but IAP causes systemic inflammation. It slowly damages the endothelial lining of blood vessels, leading to hypertension and ischemic heart disease over 10–20 years,” states Dr Sachin Kumar, Director, Pulmonology & Critical Care Medicine, Sakra World Hospital, Bangalore.
Triggering symptoms
In a clinical setting, doctors often see respiratory and cardiac conditions linked to indoor air pollution daily, yet they are rarely labeled as such. “For decades, Chronic Obstructive Pulmonary Disease (COPD) was considered as a ‘smoker’s disease’ but when a non-smoker presents with breathlessness, clinicians often default to asthma or age caused due to diet, exercise rather than identifying Biomass-COPD. But fuel used to cook and incense sticks or mosquito coils used daily are never considered the cause,” he adds.
Lack of ventilation
Dr Kumar frequently treats patients from “modern” homes suffering from chronic coughs. This is often due to two factors – fuel stacking and the ventilation trap. “Modern homes are often designed to be “dust-proof” and “air-conditioned,” which paradoxically makes them airtight. Without a high-suction electric chimney, even “clean” LPG combustion produces nitrogen dioxide (NO_2). Therefore, when home lacks cross-ventilation, pollutants from cooking, incense (agarbatti), and mosquito coils are trapped, creating a “gas chamber” effect.”
Serious consequences
A single mosquito coil can emit as much PM2.5 as 100 cigarettes. Since women spend more time near cooking areas, they are at higher risk of developing chronic obstructive pulmonary disease (COPD), heart disease, stroke and lung cancer, even if they have never smoked. Prolonged exposure also results in low birth weight, stillbirths etc. “Children are uniquely vulnerable because they breathe more rapidly and are often “mouth breathers,” which bypasses the natural filtration of the nose. This leads to stunted lung development, essentially a permanent reduction in their lifelong breathing capacity, and allows fine particulate matter (PM2.5) to cross the blood-brain barrier, which is increasingly linked to neurodevelopmental delays and cognitive “brain fog.” Indoor air pollution can also lead to stroke, depression and sleep deprivation among the elderly,” says Dr Kumar. Globally, nearly half of pneumonia-related deaths among children under five are associated with household air pollution, notes UNICEF.
Identifying indoor pollution
It’s important to note that when we don’t even identify indoor pollution as worrisome, its diagnosis and treatment can’t be done properly.
Dr Dharit Shah, Consultant Pulmonologist, HCG Hospitals, Ahmedabad, reveals that patients frequently present with chronic cough, wheezing, breathlessness, or recurrent chest infections and are often managed as cases of allergy or infection. However, when symptoms persist despite appropriate therapy, environmental exposure inside the home is a common underlying factor. “Simple questions regarding cooking fuel, ventilation in the kitchen, use of incense or mosquito repellents, and exposure to indoor smoking can reveal continuous low-grade pollutant exposure that aggravates or sustains symptoms,” observes Dr Shah.
He adds that conditions like asthma and chronic obstructive pulmonary disease that appear poorly controlled often improve when indoor irritants are reduced. He says, “Recognition of these factors also helps avoid repeated antibiotic courses and unnecessary investigations, allowing treatment to focus on preventive and corrective measures rather than escalating medication.”
Preventive measures
Adequate ventilation while cooking, regular use of exhaust fans or chimneys, and opening windows can effectively reduce exposure to harmful fumes. Health practitioners also warn against the use of incense sticks and mosquito coils, particularly in closed rooms. Dr Shah points out, “One should also avoid smoking indoors and maintain cleanliness through wet mopping. Regular washing of curtains will also help in reducing indoor pollutants and allergens.”
Key figures (Source: WHO)
- Among these 2.9 million deaths from household air pollution exposure. 32% are from ischaemic heart disease. 12% of all deaths occur due to ischaemic heart disease can be attributed to exposure to household air pollution.
- 23% deaths occur due to stroke. Approximately 12% of these deaths can be attributed to the daily exposure to household air pollution arising from using solid fuels and kerosene at home.
- 21% are due to lower respiratory infection. Exposure to household air pollution almost doubles the risk for childhood LRI and is responsible for 44% of all pneumonia deaths in children less than 5 years old.
- 19% deaths are caused by chronic obstructive pulmonary disease (COPD) and 23% of all deaths from COPD in adults in low- and middle-income countries are due to exposure to household air pollution.
- 6% are from lung cancer. Around 11% of lung cancer deaths in adults are attributable to exposure to carcinogens from household air pollution caused by using kerosene or solid fuels like wood, charcoal or coal for household energy needs.
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