Do you know that one could die from indoor air pollution? According to World Health Organization (WHO), 4.3 million people a year die from the exposure to indoor air pollution, and it accounts for nearly 3% of global burden of disease. Indoor Air Pollution and India  Compared to other countries, India has among the largest burden of disease due to the use of dirty household fuels and 28% of all deaths due to indoor air pollution in developing countries occur in India. Indoor air pollution is second biggest killer after high blood pressure in India. According to WHO statistics, nearly 12.5 lakh people died in India because of indoor air pollution in the year 2012, in which 8% were the children below 5 years who died due to lower respiratory infections (LRI), particularly pneumonia. Chronic obstructive pulmonary disease (COPD), ischaemic heart disease (IHD), and stroke were the major cause of deaths in adults. Indoor Air Pollution and Cooking Practices in India Use of fossil fuel for cooking purpose is the prime factor for increase in Indian indoor air pollution, especially the biomass fuel (animal dung, crop residues and wood) that is used in 80% of rural households, which comprises 70% of Indian population. Only 0.1% of Indian population uses electricity for cooking. Indoor smoke from cooking contains harmful particulate matters, carbon monoxide, nitrous oxides, sulphur oxides (mainly from coals), formaldehyde, cancer causing substances, such as benzene and polycyclic aromatic hydrocarbons (PAHs), etc. Pollutants level in kitchen smoke (mg/m3) Carbon Monoxide Polycyclic Aromatic Hydrocarbons Formaldehyde Dung 144 3.56 670 Wood 156 2.01 652 Coal 94 0.55 109 Kerosene 108 0.23 112 LPG 14 0.13 68 Approximately 17% of annual premature lung cancer deaths in adults are attributable to exposure to carcinogens from household air pollution caused by cooking with solid fuels like wood, charcoal or coal. Rural women are the probable victims of pollutants releasing during cooking because in India they spend most of their time in cooking. Women exposed to high levels of indoor smoke from biomass fuels are more than 2 times as likely to suffer from chronic obstructive pulmonary disease than women who use cleaner fuels, like LPG. Infants also get exposed to these harmful pollutants, as they are often carried on their mother’s back during cooking. Over half of deaths among children less than 5 years old from acute lower respiratory infections are due to particulate matter inhaled from indoor air pollution from household solid fuels. Indoor Air Pollution and Urban India People dwelling in metropolitans and urban India use cleaner fuels for cooking. They don’t use biomass fuels it doesn’t mean that they are safe from indoor air pollution.  The prescribed value by WHO for particulate matters in air is 20µg/m3, and in India, the average value is 375µg/m3. In a study of ICMR in Chennai, an increase of 0.3 % to 0.6 % in mortality is observed with rise in particulate matter pollution by 10µg/m3. The term Particulate Matter (PM) is widely used for mixture of very small particles of dust, pollen, ash, soot, metals and other chemicals found in atmosphere. The health risks associated with PM is invariably coupled with particle size. Particles with diameter less than 2.5 micron (PM2.5) are small enough to penetrate deep into the lungs and thus serve as a carrier medium for toxic virus and gases causing acute respiratory symptoms while PM10 (particles with diameter < 10 µm) have been associated with emergency hospital admission for bronchitis, pneumonia and asthmatic disease in older people. As per the data provided by World Bank, 3 of the world’s 20 cities having highest PM10 levels were in India, while 10 Indian cities had highest PM2.5 levels across the globe. Obviously, people are exposed to air pollutants both outdoors and indoors but inside a building, they are exposed to pollutants generated outdoors that penetrate to the indoor environment and also to pollutants produced indoors, which makes the inside air more dangerous than outside air. The experts say that indoor air can be 5 times more polluted and fatal than outside air. In a survey conducted by Artemis hospital in 2016, it is found that 47 per cent people in National Capital Region (NCR), who mostly stay indoors during the day, have symptoms of various respiratory disease, such as rhinitis, asthma, decreased resistance to respiratory infections and chronic obstructive pulmonary disease. Categorization and Grouping of Indoor Air Pollutants On the basis of their source, indoor air pollutants can be broadly classified into three major categories: Chemical, like benzene, formaldehyde, etc.; Physical, like dust, particulate matters, etc.; and Biological, like pollen, mold, etc. On the basis of their physical state, they can be divided into two groups: Gases, and Solid particles. On the basis of their origin, they can be segregated into two categories: Primary, and Secondary. There are numerous ways of classifying and grouping indoor air pollutants. One of the most common groupings that one often encounters in the context of indoor air pollution is volatile organic compounds (VOCs). VOCs are chemicals having long chains of carbons that easily vaporize at room temperature because of their low boiling points, especially less than or equal to 250° C measured at a standard atmospheric pressure of 101.3 kPa. They have no colour, smell, or taste. Benzene and PAHs are among the most fatal VOCs. List of Volatile Organic Compounds Acetaldehyde Acetone Benzene Carbon tetrachloride Ethyl acetate Ethylene glycol Formaldehyde Heptane Hexane Isopropyl alcohol Methyl ethyl ketone Methyl chloride Monomethyl ether Naphthalene Styrene Toluene Xylene WHO divided the indoor air pollutants into two categories on the basis of the need of indoor air quality guidelines. The categorization doesn’t include Environmental Tobacco Smoke (ETS), as it doesn’t need separate guidelines for indoor environment. The guidelines are equally valid for both indoor as well as outdoor air. The risk of toxicity from inhaling them would be the same whether the exposure are indoors or outdoors. WHO guidelines framed WHO guidelines not framed Benzene Carbon monoxide Formaldehyde Naphthalene Nitrogen dioxide Particulate matter (PM2.5 and PM10) Polycyclic aromatic hydrocarbons, especially benzo-[a]-pyrene Radon Trichloroethylene Tetrachloroethylene Acetaldehyde Asbestos Biocides, pesticides Flame retardants Glycol ethers Hexane Nitric oxide Ozone Phthalates Styrene Toluene Xylenes Indoor Air Pollution and WHO Guidelines Pollutants Effects Guidelines Benzene Acute myeloid leukaemia (sufficient evidence on causality) Genotoxicity No safe level of exposure can be recommended Unit risk of leukaemia per 1 µg/m3 air concentration is 6 × 10–6 The concentrations of airborne benzene associated with an excess lifetime risk of 1/10 000, 1/100 000 and 1/1 000 000 are 17, 1.7 and 0.17 µg/m3, respectively Carbon monoxide Acute exposure-related reduction of exercise tolerance and increase in symptoms of ischaemic heart disease (e.g. ST-segment changes) 15 minutes – 100 mg/m3 1 hour – 35 mg/m3 8 hours – 10 mg/m3 24 hours – 7 mg/m3 Formaldehyde Sensory irritation 0.1 mg/m3 – 30-minute average Naphthalene Respiratory tract lesions leading to inflammation and malignancy 0.01 mg/m3 – annual average Nitrogen dioxide Respiratory symptoms, bronchoconstriction, increased bronchial reactivity, airway inflammation and decreases in immune defence, leading to increased susceptibility to respiratory infection 200 µg/m3 – 1 hour average 40 µg/m3 – annual average Polycyclic aromatic hydrocarbons Lung cancer No threshold can be determined and all indoor exposures are considered relevant to health Unit risk for lung cancer for PAH mixtures is estimated to be 8.7 × 10–5 per ng/m3 of B[a]P The corresponding concentrations for lifetime exposure to B[a]P producing excess lifetime cancer risks of 1/10 000, 1/100 000 and 1/1 000 000 are approximately 1.2, 0.12 and 0.012 ng/m3, respectively Radon Lung cancer Suggestive evidence of an association with other cancers, in particular leukaemia and cancers of the extrathoracic airways The excess lifetime risk of death from radon-induced lung cancer (by the age of 75 years) is estimated to be 0.6 × 10–5 per Bq/m3 for lifelong non-smokers and 15 × 10–5 per Bq/m3 for current smokers (15–24 cigarettes per day); among ex-smokers, the risk is intermediate, depending on time since smoking cessation The radon concentrations associated with an excess lifetime risk of 1/100 and 1/1000 are 67 and 6.7 Bq/m3 for current smokers and 1670 and 167 Bq/m3 for lifelong non-smokers, respectively Trichloroethylene Carcinogenicity (liver, kidney, bile duct and non-Hodgkin’s lymphoma), with the assumption of genotoxicity Unit risk estimate of 4.3 × 10–7 per µg/m3 The concentrations of airborne trichloroethylene associated with an excess lifetime cancer risk of 1:10 000, 1:100 000 and 1:1 000 000 are 230, 23 and 2.3 µg/m3, respectively Tetrachloroethylene Effects in the kidney indicative of early renal disease and impaired performance 0.25 mg/m3 – annual average Some Unnoticed Sources of Indoor Air Pollutants Air Fresheners We normally think that air freshener combats foul smell and makes a feel good ambience around us, which boosts our productivity but on the contrary, it is more harmful than good. It contains harmful chemicals, such as phthalate, formaldehyde, benzene, naphthalene, etc.  The Natural Resources Defense Council studied the effects of air fresheners and found that many air fresheners contained a phthalate known as DEP and some also contained DBP, which are listed by the California EPA’s Office of Environmental Health Hazard Assessment as a developmental toxin and female and male reproductive toxin, respectively. Do you know how most air fresheners fight bad smell? Majority of air fresheners contain 1,4-Dichlorobenzene, which is a known carcinogen and it works by attacking the receptors in the nose, and thus eliminating the sense of smell. The user only smells these air fresheners for about a minute after they have been sprayed, and then the nose cannot smell most fragrances anymore. Air fresheners also contain synthetic fragrances. Ninety-five percent of synthetic fragrances are derived from petroleum. They include benzene and aldehydes, which are known to cause cancers, reproductive effects, and problems with the central nervous system. In 2013, after a study of more than 2,000 pregnant women, the International Journal of Public Health reported that women who used air fresheners in their homes were significantly more likely to have babies that suffered from wheezing and lung infections. A 2007 study also found that using air fresheners as little as once a week can raise the risk of asthma in adults. The same report found that the risk of developing asthma was up to 50 per cent higher in people who had been exposed to air-freshener sprays. Incense Sticks and Scented Candles We light incense to lift our mood and enjoy a calm & divine feeling. Incense indeed has ingredients, like frankincense, which can lift our moods by causing chemical changes in our brains but it also has release hazardous chemicals, like carbon monoxide, formaldehyde, PAHs etc. According to the report ‘Characterization of emissions from burning incense’ published in Science of the Total Environment by  J. Jetter and others, the measured emission rates of carbon monoxide of incense ranged from 144 to 531 mg/hour. The authors estimated a peak concentration of 9.6 mg/m3 caused by incense burning and therefore concluded that carbon monoxide concentrations could exceed the USEPA’s National Ambient Air Quality Standard of 10 mg/m3 for an 8-hour average, depending on the room volume, ventilation rate and the amount of incense burned. Incense burning might be a significant contributor to carbon monoxide exposure in cultures where incense is burned frequently, for example in religious rituals. According to the article ‘Why air fresheners and scented candles can wreck your health: They could cause cancerous DNA mutations and asthma’ published in The Daily Mail by John Naish, incense fumes may be more dangerous than cigarette smoke, causing cancerous mutations in our DNA.  It further stated that incense particles from commonly used ingredients agarwood and sandalwood are more toxic to our cells’ DNA than tobacco smoke. Same is the case with scented candles. Most scented candles are made with paraffin. The oil byproduct gives off ultra-fine soot particles containing acetone, benzene and toluene, usually seen in diesel emissions, and known carcinogens. Mothballs Mothballs are small balls of chemical pesticide and deodorant, which are used to repel moths and fight bad odour. It is mostly used to protect the cloths from moulds and moths when they are not in use and kept in almirah or closets.   Two types of mothballs are available in market: naphthalene ones and paradichlorobenzene ones. Both of these are toxic not only for moths but humans also and easily sublimate into gaseous phase without going through liquid phase. The principal health concerns of exposure to naphthalene are respiratory tract lesions, including respiratory tract carcinogenicity demonstrated in animal studies and haemolytic anaemia in humans. In the absence of mothballs or other sources such as combustion of biomass, indoor air concentrations of naphthalene are just above the typical limit of detection of about 0.001 mg/m3. Since the concentration of naphthalene in the residential environment increases up to 100-fold when mothballs are used, the most efficient way to prevent high exposures would be to abandon the use of naphthalene-containing mothballs. Well, abandoning naphthalene-containing mothballs and using paradichlorobenzene-containing mothballs is also not a good idea because paradichorobenzene is the main ingredient used to manufacture the infamous pesticide DDT, and its cousins, DDE and DDD. Chlorine alone has a tendency to form DDT and DDT-like compounds when it reacts with many other substances. These compounds disrupt the endocrine system by destroying hormones throughout a body very powerful way. WHO considers paradichlorobenzene possibly carcinogenic to humans based on studies with mice. Repellants made up of neem, lavender, or cedar could be an alternative of chemical mothballs. The best advice is to keep the cloths in airtight containers after thorough washing and drying or if it is not possible then place the clothing in the dryer or in the sun once or twice a month.   Cooking Practices Apart from cooking fuel being a source of PAHs, generated particularly in unvented stoves, cooking practice (e.g. charring meat, deep frying) is another source of PAHs generated during cooking. The emissions from cooking practice depend greatly on the cooking method used, the fat content of the food and the quantity of food being cooked. Food with a higher fat content emits more PAHs than low-fat food. Also, an increase in cooking temperature generally increases the production of most PAHs. A comparative study of cooking practices showed that boiling produced the least PAHs, while broiling and frying produced most PAHs. Most Overlooked Indoor Air Pollutants that Directly Affects Health I consider following three among others as the most overlooked indoor air pollutants that directly affects people’s health. Formaldehydes Formaldehyde is a colourless gas, flammable and highly reactive at room temperature. In ambient air, formaldehyde is quickly photo-oxidized in carbon dioxide, and it also reacts very quickly with the hydroxyl radicals to give formic acid. Indoor sources may be combustion processes such as smoking, heating, cooking, or candle or incense burning. However, major sources in non-smoking environments appear to be building materials and consumer products that emit formaldehyde, which include furniture and wooden products containing formaldehyde-based resins, such as particleboard, plywood and medium-density fibreboard; insulating materials; textiles; do-it-yourself products, such as paints, wallpapers, glues, adhesives, varnishes and lacquers; household cleaning products, such as detergents, disinfectants, softeners, carpet cleaners and shoe products; cosmetics, such as liquid soaps, shampoos, nail varnishes and nail hardeners; electronic equipment, including computers and photocopiers; and other consumer items such as insecticides and paper products. There’s also a secondary source of indoor formaldehyde formation through chemical reactions between, for example, ozone and terpenes. Higher environmental concentrations may trigger breathing problems in exposed asthmatics. There is evidence that some people can develop sensitivity to formaldehyde at concentration below 0.1 mg/m3, which is the guideline value by WHO. It has also been shown to cause cancer in animals and possibly in humans. The use of low-emitting building materials and products, and preventing exposures to environmental tobacco smoke and other combustion emissions, will minimize exposure-related risk. In addition, ventilation can reduce indoor exposure to formaldehyde. Since there are multiple sources of formaldehyde formation indoors but not any remedial measures, preventive ones only, it requires special attention. Asian Paints took up the challenge to find a remedy and came up with an innovative paint, called Royale Atmos - A Paint that helps purify air, which claim to reduce indoor formaldehyde by using Activated Carbon technology. Radon Radon is a naturally occurring colourless and odourless radioactive noble gas. The most stable of the isotopes is radon-222 (222Rn) with a half-life of 3.826 days. It is a member of the uranium-238 (238Ur) decay series and its immediate parent is radium-226 (226Ra). Radon formed by the decay of uranium in soil and rocks and entering the indoor air spaces of buildings or other enclosed locations may reach concentrations of concern for health, like lung cancer, emphysema, asthma and heart disease. The main source of indoor radon is the radon produced by the soil subjacent to a house or through water supplies. All rocks contain some uranium, typically at concentrations of 1–3 ppm. The uranium content of a soil will be about the same as the uranium content of the rock from which the soil was derived. Soil gas containing radon enters a house through cracks and fractures in the foundations by pressure-driven flow, as the air in a house is generally warmer and therefore at a lower pressure than the subjacent soil gas. River and surface reservoir water supplies usually contain very little radon but groundwater may contain high concentrations, depending on the uranium/radium content of the aquifer formation. Public waterworks using groundwater and private domestic wells or borewells often have closed systems and short transit times that do not remove radon from the water or permit it to decay. This radon is out-gassed from the water to the indoor air when the water is used for washing, cooking and other purposes in a house. Radon concentrations can reach several thousand Bq/l in water from drilled wells in regions with granite rock or other uraniferous rocks and soils. This contributes to indoor radon and to exposure via ingestion but the dose to the lung per unit exposure arising from inhalation is much higher than that owing to ingestion. A very rough rule of thumb for estimating the contribution of radon in domestic water supplies is that house water with 10 000 Bq/m3 radon contributes about 1 Bq/m3 to the level of radon in the indoor air. It should be noted that radon is the second-leading cause of lung cancer in the United States of America after tobacco smoke but representative national surveys of indoor radon have not yet taken place in India. Phthalates Phthalates are hormone-disrupting chemicals that can be particularly dangerous for young children and unborn babies. Exposure to phthalates can affect testosterone levels and lead to reproductive abnormalities, including abnormal genitalia and reduced sperm production. Phthalates are used to dissolve and carry fragrances, soften plastics and also as sealants and adhesives. They are commonly found in a variety of products, including cosmetics, paints, nail polish and children’s toys. According to the Environmental Working Group, phthalates produce liver cancer, but this link has not been officially acknowledged by regulatory agencies. In 2004, the European Union banned two types of phthalates in cosmetics and children’s toys, as do 14 other countries but still no guidelines have been framed by WHO on phthalates. It is strongly recommended to avoid using products that contain phthalates and improve ventilation systems to dilute these chemicals as much as possible, if they cannot be eliminated altogether. Conclusion Indoor air pollution is a serious issue. People are dying from it every year not only in developing countries but developed countries also. It is said that indoor air is 5 times more polluted than outdoor air. Major threat of indoor air pollution in developing countries is from combustible fuels while in developed countries, it is from tobacco smoking. Apart from smoking, almost everything inside a house contributes to indoor air pollution in some way whether it is building, or furniture, or domestic or personal care products. Most of them contribute formaldehyde, benzene, and phthalates. A significant part of radon also seeps inside from water supplies and soils adjacent to the house. Ensuring proper ventilation and humidity level, use of cleaner fuels, avoiding substances that have harmful chemicals, buying only eco-friendly domestic products, and growing plants in and around the house are some measures to reduce the threat of indoor air pollution.     If you wanna appreciate the effort, please do share: Facebook Twitter Linkedin Google+ Share = Love :-) For reading the posts directly in your mailbox, fill in your email: