Indoor Air Pollution: Meaning, Types, Causes, Impact, Solution

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Indoor Air Pollution: Meaning, Types, Causes, Impact, Solution

Introduction: Environmental pollution is on the rise and this is a global issue now. This has become a serious situation in today`s world. While most of us are worried about the ‘outdoor’ air pollution impacting our health, we tend to ignore another major factor that harms us, i.e. ‘indoor pollution’.

We believe to be protected from all kinds of pollution when we are in our homes or under a roof within closed doors, but it is not so. Indoor pollution is as harmful as its outdoor counterpart, if not more.

Awareness is slowly picking up about this issue because only if we are aware, can we take the necessary precautions.


Indoor air pollution indicates the level of contamination of air within the closed doors. It points towards all the pollutants (biological, physical or chemical) which pollute the air in any indoor environment (office, house, commercial buildings, movie theaters, etc.).

Cities as well as villages are victims of indoor pollution. Under-developed and developing countries especially fall prey to indoor pollution. Indoor air pollution can be dangerous since the pollutants become more concentrated in the limited area of the indoor environment.

Generally, indoor air pollution may lead to temporary suffocation or irritation and can be easily tackled by leaving the polluted area or by possibly eliminating the cause of the pollution. But, some latent indoor air pollutants might manifest symptoms much later to cause respiratory tract illnesses,  and other symptoms, etc. Thus, it is important to know that not all indoor air pollutants are easily identifiable or visible.

The indoor air quality (IAQ) within the closed doors should be free from pollutants to ensue comfortable atmosphere for the occupants. Otherwise, the occupants might be at high risk to develop health hazards. Thus, it is of utmost importance to comprehend and limit the commonly occurring indoor pollutants to sustain a healthy living.

Long-term exposure to indoor air pollutants may cause latent adverse affects in human body that may lead to potentially harmful health hazards after years. It is also very difficult to pinpoint the exact causes of these untimely health hazards later. Indoor air pollution disturbs the balance of our good health and should be averted.

Types of indoor pollutants:

1. Carbon Monoxide: Carbon Monoxide, a colorless and odorless gas comes as a by-product when fuel burn incompletely. Carbon monoxide is also generated in indoor air from a burning cigarette. In developing countries, villages and under-developed areas majorly use firewood, cow dung manure, charcoal as fuel for cooking. This produces high amounts of carbon monoxide in rural homes. People inside small rural houses are exposed to such smoke and are prone to various health hazards. Also, staying near industrial areas contaminate the indoor air of homes with this harmful pollutant.

2. Benzene: Benzene as an indoor pollutant usually sources from the outside automobile exhaust, petrol pumps, industrial fumes, adjacent garage, etc. Indoor sources include furniture, raw materials used in building constructions/home renovation/certain home decorative, cooking stoves, some of the furnishing and polymeric chemicals like PVC/vinyl, carpets made of nylon etc. Benzene also finds its presence in furniture plywood, adhesives used for flooring, paints, fiberglass and paint removing chemicals.

Also fuels like charcoal, gas, liquid petroleum gas (LPG), kerosene, and firewood increase benzene concentration in indoor environment. Using mosquito repellents, smoking cigarettes, printing and photocopying are some of the human deeds that lead to trace level benzene pollution in indoor air.

3. Biological pollutants: Biological contaminants are those home pollutants that are produced by different types of living things. Some of the examples of biological contaminants are certain microorganisms (include bacteria, fungi and viruses), animal hair, pet saliva, dust particles, ticks and mites, roaches, insects and plant pollens. These pollutants arise from varied sources, and find home in our indoor environment.

4. Smoke particles: Smoke particles arising from cigarette smoke, fireplaces, cooking area, faulty combustion home appliances majorly contribute towards indoor air pollution. Tobacco smoke pollution inside our homes due to active/passive smoking is extremely harmful.

5. Tiny metal particles: This includes heavy metal particles like mercury and lead particles from paints, industrial fumes and car gasoline exhausts in traces. When the contaminated outdoor air enters our houses, it concentrates in the indoor air and pollutes it considerably. These can be extremely harmful if inhaled.

6. Formaldehyde: Formaldehyde is a pungent smelling colorless gas, found in industrial chemicals, adhesives, some fabrics, plywood, paper bags, rugs, carpets, etc. In industries it is use as a disinfectant germicide. Household pressed wood products used in furniture and woodwork cabinets, etc. are a major source of indoor formaldehyde pollutant.

7. Volatile organic compounds: Volatile organic compounds are a class of chemicals which are highly volatile, hazardous and are airborne in our indoor air from various sources. Some of its sources include air fresheners, gas, glues, varnishes and paints, cooking ranges, vinyl floors, carpets, cosmetics, etc. These compounds may be odorless and most of the time we remain unaware of their presence in our indoor air.


1. Outside pollution: At times, the outdoor and indoor air interacts and exchanges their elements. Thus, any pollution in the locality means there is a high chance of that polluting your indoor air as well.

Houses/buildings/offices on a busy street are constantly exposed to vehicular exhaust. Inside air in houses, located close to industrial areas, surely get contaminated with harmful chemical fumes coming out of factory chimneys. Having an automobile garage close to your indoor setup also elevates indoor air pollution. Houses close to farms and fields get polluted with plant pollutants.

2. Use of polluting equipment inside the home & in the kitchen: Central heating and cooling machines and humidification appliances contribute significantly to indoor air pollution. Usage of wood-stoves and fireplaces also add-on to indoor air pollution.

3. Use of Chemicals while cleaning: Chemical cleaning agents in our daily household chores/industries contain a lot of volatile organic compounds, which get released into the indoor air with every spray. The cleaning agents in the form of aerosols especially pollute the indoor air, contributing towards particulate as well as gaseous indoor pollution.

4. Smoking: Tobacco smoke is the source of maximum amount of the harmful indoor air pollutants. The smoke particles along with the harmful gaseous pollutants contaminate indoor air and are very hazardous to the health of the room occupants. Cigarette smoking is not only injurious to an individual`s health, but it also a menace when it comes to indoor air pollution.

5. Poor HVAC Design: Heating, Ventilating, and Air Conditioning: When indoor air has high humidity, it can elevate levels of chemicals like ozone (from photocopiers) and formaldehyde (from building raw materials) in the air. High humidity also favors microbial sustenance. Thus, maintaining proper HVAC control in an indoor environment is essential to keep your indoor air pollution in check.

6. Coal/Biomass/wood: In rural zones where domestic fuel serves as the primary source of cooking, constant dense smoke generates indoors. This is seen to have very bad impact on the rural women’s health since they are exposed to this smoke most of the time.

7. Inadequate ventilation: This is especially a problem in developed countries where in order to make the appliances sufficiently energy-efficient, indoor spaces are maintained extremely airtight. This leads to inadequate ventilation and increases the indoor pollutant concentration inside the closed airtight rooms.


Benzene and CO are extremely hazardous indoor air pollutants and cause severe long-term health issues to an extent of potential cancer risk.

(1) Breathing problems: Indoor air pollutants like VOC, particulate and smoke pollutants can cause breathing problems due to suffocation and air passage blockage.

(2) Lungs, Respiratory infections:  Diseases like asthma and bronchitis can increase when in a polluted indoor area. Also, constantly breathing polluted indoor air may decrease your lung capacity.

(3) Headache: Concentrated indoor air pollution in a closed room with poor ventilation can block your sinuses and give rise to throbbing headaches.

(4) Tiredness: Mental and physical fatigue is another symptom associated with constant exposure to indoor air pollution. Breathing contaminated air do not provide a sufficient amount of oxygen to your body, in turn making you get premature fatigue.

(5) Irritation of eyes, nose, and throat: VOC can give rise to these symptoms, if their concentration is considerable in a poorly ventilated room. Redness in eyes and burning sensation in throat with running nose may be some of the specific symptoms resulting from particulate indoor pollutants.

(6) Skin rashes/irritation: Harmful indoor pollutant exposure to skin can sensitize our skin to give allergic reaction like rashes, itching sensation, redness, etc.

Solution & Control Measures

1. Discourage use of biomass at homes: Rural women especially should be enlightened about the hazards of using biomass as a cooking fuel and should be educated for an affordable alternative instead.

2. Deforestation: This should be stopped at the earliest. Cutting down plants mean that we are killing our natural air cleaners. They are our only hope for a pollution free environment. Afforestation should be encouraged at all costs and deforestation should be vehemently discouraged.

3. Rural Education: It is important to educate the rural population about indoor pollution and all its possible rural causes. Proper ventilation lessons should also be given to rural people. Natural gas based cooking stoves should be encouraged and its advantages taught to everyone.

4. Kitchen chimneys: This is an effective way to control combustion smoke while cooking. The chimneys immediately suck up all the hazardous smoke and avoid it from spreading to the whole house.

5. HVAC: HVAC setup in indoor areas should be contracted from reputed vendors. This is a must to ensure proper ventilation in indoor areas. Cheap vendors will give you low-grade HVAC systems which might contribute to indoor air pollution through their faulty systems. Also, regular servicing of HVAC is essential to ensure its proper functioning.

6. Grow Plants at home: Growing plants in your house will help keep the indoor air fresh and clean. Plants take in CO2 to give out oxygen. They can serve as natural air cleaners in indoor areas and can be an easy solution for all indoor air pollution related problems.

7. Exhaust fan: Installing exhaust fans in kitchen are very essential. This helps exchange the indoor polluted cooking smoke with outside fresh air. And also keeps the kitchen clean of cooking related pollutants. Industries/factories should also not function without exhaust systems.

8 Clean daily: Cleaning should be done on a daily basis and there should be no slack in it. Since there is no way we can help the exchange of polluted outdoor air with indoor air, cleaning indoor spaces on a daily basis will help keep the outside pollution away.

9. Maintaining hygiene: Maintaining excellent hygienic conditions will help keep indoor air free of pollution. Regular dusting/vacuuming can get rid of the particulate and biological pollutants.


It is important to understand the several dangerous adverse effects of indoor pollution and not to turn a blind eye towards this issue. Since most of our time are spent indoors, identifying/recognizing the pollution sources and taking steps to irradiate them becomes important. Also, taking precautionary steps as well as gauging/measuring the indoor air quality by professionals should be done from time to time by one and all. Education and awareness also play a key role in dealing with indoor air pollution.
– Purbita Chakraborty

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