While the level of pollution outdoors is rising constantly to alarming levels, there also comes a point where we need to take Indoor Air Quality (IAQ) seriously to ensure we and our loved ones have a healthy and hygienic life at home. Most people do not realize that very often indoor air is up to 10 times more polluted than outdoor air. A very common thing that people normally do that even in the most polluted of cities, they often open their windows ‘to let fresh air in’. This quite often allows for outdoor pollutants to enter your home and degrade the indoor air further.

Indoor pollutants can emanate from a range of sources and sometimes we don’t even realize that chances are the air indoor is worse. Dust particles, aerosol, pollen, cleansing agents, pesticides, and many other types of minimal residues from various domestic activities often get accumulated in the home environment over a long period of time which unknowing to you keeps degrading the quality of indoor air. Commonly, volatile organic compounds (VOCs), which arise from sources including paints, varnishes, solvents, and preservatives also accumulate in our homes.

Indoor Air Quality

Meaning of Indoor Air Quality (IAQ)

For those who don’t understand the meaning of the term “Indoor Air Quality”, it is simply the quality (whether good or bad) of your surrounding air whenever you are staying, working or traveling within an enclosed space (indoors) like your home, gym, office or traveling via any mode of transportation.

Indoor air quality (IAQ) is a term which refers to the air quality within and around buildings and structures, especially as it relates to the health and comfort of building occupants. IAQ can be affected by gases (including carbon monoxide, radon, volatile organic compounds), particulates, microbial contaminants (mold, bacteria), or any mass or energy stressor that can induce adverse health conditions.

Numerous air quality experts have stated that more than 80% of the people spend 90% of their time indoors, breathing “indoor air” whether at home, office or in transport. Indoor air quality is an important parameter to determine their health and wellbeing.

Monitoring Indoor Air Quality

Indoor air quality is subject to both temporal and spatial variations, and data on these variations would be needed to determine the concentrations to which occupants are exposed or to model indoor air pollution. Since the degradation of air and environment is a dynamic phenomenon, continuous monitoring is recommended by experts to keep a regular check on the quality of indoor air.

Continous monitoring is a technique for sampling and measuring the real-time concentration of pollutants in the air. Two positive features of continuous monitoring are that

  • Peak short-term concentrations can be determined, in addition to average concentrations calculated over any period.
  • Concentration variation as a function of time can be correlated with source generation, infiltration-ventilation, and other characteristics.

Continuous monitoring requires highly trained field personnel, rigorous quality-control (calibration) procedures, and provisions for quality assurance that involves independent performance audits of routine monitoring and data-handling operations.

Techniques and instruments used for the measurement of outdoor pollution may be modified for the sampling of indoor environments. Personal monitors are increasingly recognized as powerful scientific tools for determining individual and population exposure to air pollutants. Although they are still in the early stages of application, it is clear the personal monitors can yield data that are useful in associating human activities with exposure to air pollution.

Importance of monitoring Indoor Air Quality

Good quality air is commonly termed by experts as “Mountain Fresh” and is stated to be a mixture of about 21% oxygen, 78% nitrogen and 1% other gases. However, in most cities, the oxygen level in the outdoor air is around 19%, and the level indoor is even less.

Unlike outdoor air, indoor air is recycled continuously causing it to trap and build up pollutants as time passes by. IAQ characteristics include the concentrations of pollutants in indoor air, as well as air temperature and humidity. As a result of increased awareness of the health risks of poor air indoors, governments are tightening up standards and enforcing monitoring on building owners. Initially, the standards apply to public places and office buildings. In the future, it is feasible that standards could apply to newly built residential buildings.

Major indoor air pollutants

Indoor Air Quality

There are a set of common gases, pollutants, and particles that pollute/contaminate the indoor air quality. Here is a quick list of the major pollutants that contribute to poor IAQ and the related health hazards.

Sensor Pollutant Major Sources Potential Health Effects*
CO2 Carbon Dioxide Sick Building Syndrome (SBS), Excessive Building Occupancy and Inadequate Ventilation Fatigue; Eye, Nose and Throat Irritation; Headaches; Chest Discomfort; Respiratory Tract Symptoms
CO Carbon Monoxide Non-vented or Malfunctioning
Gas Appliances, Wood and Coal Stoves, Tobacco Smoke and Vehicle Exhaust Emissions
Headache, Nausea, Angina, Impaired Vision and Mental Functioning, Fatal at High Concentrations
COPM Environmental
Tobacco Smoke
Cigarettes, Cigars and Pipes Respiratory Irritation, Bronchitis and Pneumonia in Children; Emphysema, Lung Cancer, and Heart Disease
VOC Organic Chemicals Aerosol Sprays, Solvents, Glues,
Cleaning Agents, Pesticides, Paints, Moth Repellents, Air Fresheners, Dry cleaned Clothing and Treated Water
Eye, Nose and Throat Irritation;
Headaches; Loss of Coordination; Damage to Liver, Kidney, and Brain; Various Types of Cancer
O3 Ozone Ground Level Ozone Entering Indoors; Malfunctioning Air Treatment Systems; and Office Photocopiers and Printers Eye, Nose and Throat Irritation; Coughing; Chest Discomfort; Reduced Lung Function; Shortness of Breath
NO2 Nitrogen Oxides Non-vented or Malfunctioning
Gas Appliances and Vehicle Exhaust Emissions
Eye, Nose and Throat Irritation; Increased Respiratory Infections in Children
PM TSP (total suspended particulates) PM10 (thoracic fraction ≤10 μm) PM2.5 (respirable fraction ≤2.5 μm) PM(particles ≤1.0 μm) Cigarettes, Wood and Coal Stoves, Fireplaces, Aerosol Sprays and House Dust Eye, Nose and Throat Irritation;
Increased Susceptibility to
Respiratory Infections and
Bronchitis; Lung Cancer
CHCO Formaldehyde Pressed Wood Products e.g.
plywood and MDF; Furnishings; Wallpaper; Durable Press Fabrics
Eye, Nose and Throat Irritation; Headache; Allergic Reactions; Cancer

Health issues due to poor IAQ

Poor IAQ may contribute to both short and long-term health issues which can lead to decreased productivity, absenteeism, and possible litigation. Some health effects may show up shortly after a single exposure or repeated exposures to a pollutant. Typical symptoms associated with poor indoor air quality include

  • Eye, nose, and throat irritation
  • Headache
  • Nausea
  • Dizziness
  • Fatigue.

In some cases, exposure to indoor air pollution can lead to acute and chronic respiratory illnesses including

  • Asthma
  • Lung cancer
  • Pneumonia
  • Systemic hypertension
  • Chronic obstructive pulmonary disease (COPD)
  • Asbestosis
  • Legionnaires’ disease
  • Humidifier fever

Methods to improve IAQ

Changes in building design devised to improve energy efficiency have meant that modern homes and offices are frequently more airtight than older structures. However, these improvements have led to more comfortable buildings with lower running costs, they also provide indoor environments in which contaminants are readily produced and may build up to much higher concentrations than are found outside.

Indoor Air Quality

  • Chemicals and allergens can accumulate in household dust for decades. Using a vacuum cleaner that has strong suction, rotating brushes, and a HEPA filter ensures that dust and dirt won’t get blown back out in the exhaust reduce concentrations of lead in your home. You can also get rid of other toxins, like brominated fire-retardant chemicals (PBDEs) as well as allergens like pollen, pet dander, and dust mites.
  • Mopping picks up the dust that vacuuming leaves behind. You can skip the soaps and cleaners and just use plain water to capture any lingering dust or allergens.
  • Keeping humidity around 30%-50% helps keep them and other allergens under control. A dehumidifier and air conditioner during summer months help reduce moisture in the indoor air and effectively controls allergens and thus reduces the chances of growth of dust mites, molds, and other fungi.
  • Make your home a no-smoking zone by either prohibiting people to smoke within the premise or by using an exhaust fan or crack open a window when smoking, or during other activities like cooking, running the dishwasher, or bathing.
  • Open the windows of your home for about 3-4 hours a day, especially during the early hours after sunrise to ensure proper ventilation and flow of fresh air to and fro your premise. Keeping windows open during for a few hours from sunrise is suggested because the air outside possesses the most soothing temperature and is cleaner because the daily life and outdoor air polluting activities don’t begin that time.
  • Keeping windows open for a fair amount of time also helps keep a check on humidity. Recommended average humidity indoor should be maintained at around 30-50%.
  • Install and use Indoor Air Purifiers, that help capture and suck out dust and other particulate matter from the premise.

Apart from these basic steps to improve indoor air quality, you can also invest some money in installing an Oxygen Optimizer or Oxygen Generator in your home. These are advance air recycling products that sit on your windowsill, harvests oxygen from the outside air, and pumps it inside. Thus you get the right amount of oxygen–inside your own room.

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An Oxygen Generator actively changes the mixture of air as compared to Indoor Air Purifiers which only catch particulate matters circulating through its vents. Indoor air purifiers is a decent step to purify indoor air but is a passive technology.