Indoor air pollution and ventilation

People spent majority of their time indoors. It is therefore important to provide healthy and qualitative air indoor environment. Air quality within and around the buildings also influence comfort of building occupants.

It is of importance to know which pollutants are commonly present and how to eliminate them in order to reduce health concerns.

Indoor air can contain wide range of airborne and gaseous pollutants including volatile chemicals, particles, and biological contamitants. Pollutants that exists constantly in our surroundings are of various sizes and positions. They include microorganisms such as fungi, bacteria, endotoxins, particles that include viruses and pollen, carbon dioxide, volatile organic compounds, radon, etc.

Health effect from indoor air pollutants can be experienced immediately or after longer period of time.

Immediately after exposure to polutants or after repeating exposure some health problems - like irritation of eye, nose, and throat, headaches, dizziniess, and fatigue, might occur. These are usually short term effects and are treatable. Solution can be avoidance of exposure to the sources of pollution.

Exposure to some indoor pollutants may cause asthma, that can be worsened over time if the sources are not eliminated. Whether symptoms to air pollutants in indoor air will appear depends also on age and sensitivity of person to exposure.

Sources of indoor air pollution have to be identified in order to prevent developing of symptoms, or more serious health problems. Some effects can appear if enough fresh air is not supplied from outdoor, or if heating, cooling or humidity cause indoor conditions that can harm health.

Other health effects may show up years later or after repeated exposure over years. These effects can be respiratory diseases, hearth desease and cancer.

It is important to detect air pollutant and improve quality of air indoor in order to prevent developing of symptoms. In developing symptoms, it is of importance uncertainity of time of exposure to pollutants.

It is essential to understand which health effects occur after exposure to the average pollutant concentratuon and what is the time period of exposure needed to develop symptoms.

Pollutants that are usually found indoor and couse many harmful effects are:

  • Heating systems, ie. fuel needed for combustion appliances
  • Tobacco products, ie. cigarrettes smoke
  • Building material and furnishing
    • if they contain asbestos
    • new flooring or carpet
    • furniture or cabinets made from pressed wood products
  • Cleaning products for house
  • Central heating systems, or central cooling systems, and humidification devices
  • Moisture, if present in excees
  • Outdoor air pollutant sources like radon (Rn), pesticides, carbon monoxide (CO), Lead (Pb), Nitrogen Oxide (NO2), and other outdoor air pollutants.

Key factor is concentration of polluttants and how hazardous their emmisions are.

Some building materials or furnishing can release pollutants more or less continiously.

Unvented or mafunctioning appliances or improperly used products can release higher or sometimes dangerous levels of pollutants indoors.

Pollutant concentration can remain in the air for long period of time if not properly removed. It can be removed by using natural or mechanical ventilation or professionally removed.

If too litle outdoor air enters indoors pollutants can accumulate to levels that can couse health and confort problems.

Outdoor air can enter or leaves building by inflitration or via natural ventilation and mechanical ventilation. Infiltration is when otdoor air flows into building through openings, joints, cracks in wall, floors, ceilings, sand around doors or windows. In natural ventilation, air moves through opened windows and doors, and is coused by temperature difference and wind. Devices for mechanical ventilation continiously remove indoor air and distribute filtered and conditioned outdoor air at certain exchange rate.

If there is little infiltration, natural or mechanical ventilation, air exchange needed to provide fresh air is low and pollutant levels increase.

Common air pollutants

Carbon monoxide (CO) is odorless and invisible gas, produced by process of incomplete combustion of fossil fuels in heating systems.

It prevents body from taking the oxygen. Symptoms of exposure are tiredness, headaches, dizzines, nausea, confusion, and fast heart rate. In excess of concentration exposed person could die.

To prevent CO as pollutant in your home you should check your heating system regularly (ex. yearly) and make sure they are installed correctly. Also, make sure to provide adequate ventilation.

Radon (Rn) is odorless and colorless gas found in low levels all around, that is naturally produces by break down of uranium in Earth.

Exposition to elevated levels of radon increases risk of cancer.

Home should be screened for elevated radon levels by professionals and if present it has to be removed.

Nitrogen oxide (NO2) is toxic and corrosive gas.

It irritates throat, eyes, nose, and respiratory tract. Exposure to high doses can lead to pulmobary edema or lung injury. Moderate exposure can lead to acute or chronic bronchitis. Low level exposure can impair lung function. Susceptible to nitrogen oxide arte people with asthma and chronic obstructive lung disease.

Make sure that heating systems are installed correctly and that house is ventilled frequently.

Secondhand smoke appear as cigarettes smoke and it comes from incompletely burned tobacco products. Tobaco smoke cotain 4700 chemical ingredients.

Exposure to seconhand smoke can cause eye, nose, and throat irritation. In the long run it can cause wheezing, pneumona, bronchitis, and lung cancer. Also asthma can be triggered.

Lead is naturall and soft metal, very toxix if consumed. It was used in house paint before.

Exposure can lead to damage of brain, nervous system, kidneys and red blood cells. In children it develop short attention spans, behavoural problems, lower IQ levels, and delayed growth.

Make sure that play areas of children and toys are clean, frequently clean and mop the floors.

Asbestos is group of minerals found natirally all over the world. It is hazardous air pollutant. If asbestos fibers are disturbed thay become airborne and can ptentially enter the lungs.

Exposure to asbestos can leas to various lung disorders including lung cancer and asbistosis. Asbestosis is inflammatorx condition of the lungs that causes coughing, trouble brathing and permanent lung damage.

If products in your house that contain asbestos are in good condition keep them good, if not remove them by trained professional.

Molds are type of fungi that grow indoors and outdoors. Some types of molds are dangerous, some are not.

Molds can trigger allergic reaction in some people. Symptoms that may appear are nasal stuffiness, eye or throat irritation, swelling, coughing or wheezing, headaches, or skin irritation. Severe exposure can lead to fever or trouble breathing.

Make sure that appliances that create moisture are vnted and provide naturall ventilation.

Architectural design

Good architecture and design are the most important means of reducing and controlling the presence and growth of indoor air pollutants.

Architects should consider multiple parameters before designing home or building to provide good air quality. With enabled proper ventilation, natural and mecanical, good exposure to natural light, building envelope insulation, and sustainably sourced non toxic material for construction architects can apply best practices while working on projects for home.

Proper natural ventilation is one of the first consideration when designing. Building orientation and well studied opennings layout is next step that would promote effective airflow through space including cross ventilation and cooling towers. Implementing a functional hybrid ventilation system inddors could contribute to the dilution of some contamitants.

Architects should design proper and well controlled aerated dwelling, and manage building air leakage by maintaing stableindoor air pressure. They can also prevent entrance of air infiltration that potentially contain pollutants.

Natural ventilation is generally prefered and is considered to be CO2 free. Mechanical ventilation use lots of energy, and air entered can contain outdoor emissions such as traffic pollution and other micro-particles. Design strateges like isolating connected spaces or disconnecting building spaces, or compartmentalization can also be considered.

In addition to above, smart mechanical ventilation with proper filtration and heat recovery can be used.

Complementary to natural ventilation, artificial indoor heatoing and cooling systems could be equiped with specific filters that reduced pollutant particles.

It is also important to control humidity. This begins by having dry construction process including steel or timber framing.

One of the most effective ways to mitigate the propagation of indoor air contamitants is by choosing the best material. Pollution sources can also be eliminated.

Implementing toxine diluting material is one of easiest ways to maintain safe airdoor quality. It offers more practical and afforadable solution for new constructions, restauration or renvation projects.


In conclusion, our homes can contain many air pollutants and therefore have to be maintained, checked and properly designed. A few smart choices for natural or mechanical ventilation, cleaning or removal of pollutants, along with good designs can improve environmental quality of our spaces and increase our general well being.



  1. Indoor Air Pollution and Health,
  2. Seven common air pollutants,
  3. How to Transform a Polluted Indoor Environment into a Healthy Home,