Recommendations to Improve Indoor Air Quality

Indoor air quality or IAQ can complement interior design, creating indoor spaces that are both visually appealing and healthy. A key requirement for IAQ is keeping air pollutants at low concentrations, and there are many ways to achieve this. Pollution sources should be minimized, while making sure the building has an adequate ventilation system. There are also air filtering and purification methods that can remove pollutants directly.

Improve Indoor Air Quality

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Controlling air pollutants is a technical challenge, since many of them are colorless and odorless. In fact, some air pollutants even have pleasant smells – volatile organic compounds (VOC) released by air fresheners are one example. However, these substances can irritate the respiratory system, and they are especially harmful for asthma patients.

Humidity control is also important for indoor air quality. Although humidity is not considered an air pollutant, it stimulates the growth of mold, dust mites and bacteria. These organisms are all detrimental for air quality and human health.

How Adequate Ventilation Improves Air Quality

The US Environmental Protection Agency has determined that indoor air contains 2 to 5 times more pollution than outdoor air. This applies even for urban environments, except at times when heavy traffic and other emission sources cause peaks in air pollution.

Since outdoor air is generally cleaner than indoor air, a well-designed ventilation system can help preserve air quality. Indoor air is constantly removed from the building to eliminate pollutants, and it is replaced with fresh outdoor air.

Indoor air quality can be monitored with sensors, and ventilation systems can be controlled based on the measurements. When a sudden increase in air pollution is detected, the outdoor air supply can be increased to reduce the concentration of harmful substances.

Eliminating Air Pollutants at the Source

Ventilation systems can control indoor air quality better when pollutants are eliminated at the point of emission. The first step is identifying the main sources of indoor air pollution, to eliminate them or minimize their impact. The following are some common sources of air pollutants:


  • Combustion of any type releases harmful substances into the air. Carbon monoxide is particularly dangerous, since it becomes lethal for humans at concentrations under 1%. Any appliance with a flame should be vented, to remove combustion products before they mix with indoor air.
  • Volatile organic compounds (VOC) come from many sources, which include new furniture, recently applied paint, cleaning products, air fresheners and cosmetics. However, many of these products are available in low-VOC versions.
  • Mold spores and dust mites are also detrimental for air quality. Since both of them are microscopic, they are very difficult to eliminate directly. The best strategy is reducing air humidity, since both mold and dust mites depend on it to stay alive.


These are some of the most common air pollution sources in building interiors. Ventilation can improve air quality, but even better results are possible if pollution sources are minimized.

Air Filters and Purifiers

A third strategy to improve air quality is removing pollutants directly from the air. Since these methods normally consume energy, relying on them exclusively is not recommended. Ideally, IAQ should be achieved with a combined approach: eliminating air pollution sources, providing effective ventilation, and purifying indoor air.

High Efficiency Particulate Air (HEPA) filters can remove many pollutants from the air, since the capture 99.97% of particles with a diameter of 0.3 microns or more. These can be used with a vacuum cleaner to prevent the accumulation of dust and other pollutants.

Indoor plants can be considered living filters, since they absorb many harmful substances as part of their normal metabolic processes. However, flowering plants should be avoided indoors, since the pollen they release can cause irritation and allergies.

Air purifiers that use ozone are not recommended by HVAC engineers, since the ozone released is considered a pollutant in building interiors. While these purifiers remove some pollutants, they defeat their own purpose by producing another one. Ozone is beneficial in the upper atmosphere where it blocks harmful radiation, but it causes respiratory irritation and paint a ground level.

Improves Air Quality

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Indoor air quality is an excellent complement for interior design, achieving an indoor environment that is both aesthetically pleasing and healthy. There are many ways to improve IAQ, but the best results are achieved with a combined approach. Ideally a building should have minimal pollution sources, an effective ventilation system, and adequate air filtering devices.


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