When homeowners and building managers plan renovations, they often focus on improving appearance. Many building upgrades also focus on performance aspects, such as energy efficiency and temperature control. However, indoor air quality (IAQ) is often overlooked, and it has a major impact on comfort and health.

Detecting air quality problems is a challenge since their effects are not always obvious. Issues like energy waste and water leakage are given more priority since they have a direct impact on utility bills. A common warning sign of poor IAQ is the “sick building syndrome”, where the health of occupants worsens as they spend more time indoors.

Problems with poor indoor air quality can reignite allergies related to the eyes, nose and throat, or can cause fatigue, nausea or illness. Within the work environment, these issues can lead to poor work performance and productivity. If left unaddressed, it could also lead to long-term issues such as sickness, missed days off work and loss of income. As an employer, you have a duty of care to ensure you protect the health and safety of your workforce.

Many air pollutants are difficult to detect because they are colourless, odourless or both.

One example is carbon monoxide (CO), a highly poisonous gas that is released by combustion devices. It should not be confused with carbon dioxide, which is produced by living organisms and much less dangerous. While CO is dangerous at concentrations below 1%, CO2 must reach levels close to 10% to become life-threatening.

How to Improve Indoor Air Quality

There are many ways to improve indoor air quality, and the best results are obtained when several strategies are used together. Homeowners and businesses  can combine the following approaches to make indoor spaces healthier:

  • Identify and minimize the sources of indoor air pollution.
  • Provide adequate ventilation for all indoor spaces.
  • Improve air quality with filtering and purification methods.

Your IAQ strategy should focus on eliminating pollutants at the source since the benefit is permanent and free. Ventilation systems, filters and air purifiers can also improve air quality, but they come with an operating cost. Also, consider that these systems work harder if air pollution sources are not controlled.

Particulate Matter and Volatile Organic Compounds

Many of the air pollutants that affect buildings can be classified as particulate matter (PM) or volatile organic compounds (VOC). Both pollutant types irritate the respiratory system, and long-term exposure has been linked with health issues like cardiac disease and lung cancer. Asthma patients are especially vulnerable since PM and VOCs can cause flare-ups.

Particulate matter is released by combustion appliances with poor ventilation. It can also be formed when other air pollutants undergo chemical reactions. The term “fine particulate matter” is used when the particle diameter is below 2.5 microns. This is the most dangerous type since it can reach deep into the lungs, entering the bloodstream. The following recommendations can help you control PM in building interiors:

  • Make sure all combustion devices have adequate ventilation. For example, the stove in your kitchen should have a hood.
  • Avoid anything that has an open flame, and this includes scented candles.
  • Prohibit smoking inside the building.

Volatile organic compounds can be misleading since many of them have smells that are considered pleasant. For example, new furniture has a characteristic smell because it is impregnated with chemicals from the manufacturing process. High concentrations of VOCs can also be found in cleaning products, cosmetics, air fresheners, dry cleaned clothes and many other household items.

  • When purchasing any of the products mentioned above, look for low-VOC versions. This is normally indicated on their labels. If you’re buying a leather couch or recliner, many brands are beginning to apply CertiPUR-US certified foam, which is another step in the right direction of low VOC emissions
  • New furniture and dry cleaned clothes should be left outside for a few days, so they can release chemicals. Off-gassing is higher initially, and then it decreases.

How Humidity Affects Indoor Air Quality

Humidity is not an air pollutant strictly, but high humidity has a negative effect on air quality. Organisms like mould, mildew and dust mites thrive in humid environments, and they reduce air quality. However, the air should not be excessively dry either, since dust and other particles stay airborne for more time. Dry air can also irritate the skin, eyes and respiratory system.

Michael Tobias is the founder and principal of Chicago Engineers, an Inc 5000 Fastest Growing Company, HVAC engineers recommend keeping relative humidity between 30% and 60%, and ideally between 40% and 50%. Air quality issues are minimized within this RH range.

Designing Ventilation Systems to Reduce Air Pollution

Ventilation systems are normally sized based on floor area and the expected number of occupants. However, IAQ can be improved if the ventilation system responds directly to air pollution levels.

The concentration of harmful substances like PM and VOCs can be measured with specialized sensors. Once the sensors are installed, ventilation controls can be configured to increase airflow based on air pollution levels. The US Environmental Protection Agency found that indoor air is normally 2 to 5 times more polluted than outdoor air, even in urban locations. When a ventilation system replaces indoor air with outdoor air, pollutant concentrations are reduced.

Air purifiers and filters can remove pollutants directly from the air, complementing ventilation systems. However, air purifiers consume electricity, and filters increase the workload on fans by restricting airflow. To improve IAQ without wasting energy, the first measure should be minimizing the sources of air pollution.