COVID-19, How it has changed indoor environments

Radon Awareness
Schools and IAQ

COVID-19, How it has changed indoor environments

The COVID-19 virus has forever changed our perspective on cleanliness, personal interaction, and our environment. The thought of a post-pandemic state brings us hope. But what does a post pandemic environment look like and how does it operate? Indoor Air Quality Associates has collaborated with industry partners and health experts to present some of the most effective ways to make our buildings safer. From filters and air changes in HVAC systems to sanitization, as well as technology integrations for IAQ monitors and analytical COVID-19 air testing, there are short and long-term strategies building owners can implement to increase the safety of their building. These building systems, IAQ product, and a health and safety reopening plan will reassure occupants that the buildings they are returning to have evolved to keep pace with the latest in health and safety guidelines.


In summary, COVID-19 is a new highly contagious virus that predominantly spreads through contact and dispersion of droplets between people and nearby surfaces. Because of this contagion level, as people return to the workplace we will need to take these precautionary steps for personnel, furniture, and HVAC and even plumbing systems. These measures will need to be put in place during and even post pandemic. Yes, we said post pandemic! If this has taught us anything, our environmental and indoor air have a tremendous effect around the health and wellbeing of us.

HVAC solutions

Controlled access, separation and cleaning represent the some of the primary defenses against the spread of the virus. However, protections may be applied to existing and new HVAC systems to minimize further spreading of the virus within the workplace.

Several measures may be adapted from practices that healthcare and Bio-Safety Level (BSL) research facilities use to protect staff. It must be noted that measures applied to infectious disease rooms, BSL laboratories and clean spaces are designed for specific applications under highly controlled environments and access.

Clean rooms control particulate of specific sizes and rely on laminar airflow within the space to minimize recirculation of contaminants and to promote capture. Clean rooms require airflow injected high across large areas of the ceiling and discharged at low velocity to direct airflow down to low returns located at the perimeter of the spaces. Modifying HVAC systems to a similar configuration for office spaces would be extremely expensive. Furthermore, with modernized in space equipment the goal of clean air can still be achieved.

Some other ways to achieve clean air and environments include:

Installing filtration (antimicrobial filters, HEPA, or ULPA filters), and bi-polar ionization at return air openings and at components within the air system

Implementing pressurization control and/or enhance current practices

Increasing airflow (recirculated and outside air)

Deactivating demand control systems that limit concentration of outside air

Operating systems longer and with higher outside air content to flush spaces due to increased use of cleaners

Operating ventilation systems serving communal spaces such as toilet rooms continuously (24 hours/day), since they have a higher risk of contamination

Maintaining minimum relative humidity levels

Sanitizing ductwork with bi-polar ionization

Using portable air purifiers.

Increase filtration efficiencies (if equipment can handle the additional restriction)

For any particulate matter that is captured and pulled into the HVAC system, filtration may be effective if properly applied. First, understand that the size of the coronavirus (as well as all viruses) is very small and will pass through almost all filters if independently suspended in the airstream. Refer to figure in this link. However, filters will intercept larger particulate that may contain the coronavirus.  It is understood that the virus will attach to airborne particulate such as dust, which are captured by the high efficiency filters. The efficiencies of the typical HEPA or ULPA filter is based upon particles at 0.3 micron. Note, HEPA filters and higher efficient ULPA filters will still capture a percentage of particles smaller than 0.3 microns. Also, the efficiency of these filters will improve as they become loaded, so it is not desirable to constantly change these filters. The main disadvantage to utilizing HEPA or ULPA filters in an existing HVAC system is the high pressure drops of these closely weaved filters. To minimize the pressure drop and the impact to an existing fan system, lower depth HEPA filters may be utilized or use our proprietary ULPA technology that has a lesser pressure drop then the industry. Another option would be to add booster fans / or upgrade to modernized fan walls to accommodate the higher pressures.

To further enhance the effectiveness of filters, it is advisable to add bi-polar ionization to attach smaller particles to each other, thus making them larger to be captured by a mechanical filtration system or even fall to the lowest horizontal surface.

Bipolar ionization

This technology releases positive and negative ions into the airstream. Air flows along the needlepoints the air is then charged to form ions. The ions are attracted to airborne particles like dust, smoke, VOC’s, allergens and other air pollutants. The ions latch onto and neutralize any contaminants they come into contact with. Charged particles are drawn together, forming clusters, which become heavy enough to drop out of the air. These ions work to deactivate single-celled, carbon-based organisms such as fungi, viruses and bacteria, whether they’re in the air or resting on surfaces. Note, this technology does not remove the contaminant but will help the enhanced filtration system capture the contaminant or help to break it down.To be effective, it is recommended that this technology constantly operate to maximize effectiveness.

Pressurization and air flow

Pressurization techniques may be employed to minimize the risk of outside contamination that is not carried in with people or materials. Installation of airlocks or active pressurization controls can make the workplace positive with respect to adjacent spaces.

For systems with demand ventilation controls, these controls should be deactivated (during this crisis period) to maximize the amount of outside air ventilation introduced into the spaces.

HVAC systems that introduce outside air may be operated for longer periods to increase the time that the spaces are occupied for multiple shifts and to flush them with fresh air. Application of frequent cleaning procedures within the workplace will release chemicals into the air. The implementation of flush-out cycles will capture and dilute the air within the workplace prior to workers returning the following day. During unoccupied periods, the amount of outside air may be increased beyond minimum outside air setpoints. If interior conditions (temperature and relative humidity) are relaxed during this flush-out period, it will be possible to further increase the amount of outside air during peak cooling and heating months. Depending upon existing controls in place, it may be possible to enact automatic controls and setting of outside air volume, based upon monitoring interior conditions during these unoccupied period flushing cycles, by simple reprogramming of the control sequences. For higher risk-communal spaces, it is prudent to operate these systems continuously – 24 hours a day.


Humidification should also be considered to help minimize the spread of contagions. As noted by many building scientist, healthcare professionals, and public health professionals humidity above 40% inactivates almost 80% of viruses within 15 minutes. Humidification introduced by steam injection is a logical choice, but other methods, such as ultrasonic or spray injection, may be explored if sanitization of the system is maintained. Systems that rely on maintaining standing water are not recommended. Since the majority of office HVAC systems may not utilize humidification, these systems would need to be retrofitted, which would include a clean water source, a unit coupled with energy to heat to inject moisture, and a distribution method – either by injection into a duct system or the use of area humidifiers that inject moisture directly to the occupied spaces.

Air purification

Another option to increase air changes within a space while treating the airflow is the use of multiple air filters and purifiers. These provide the ability to increase air changes when the existing HVAC systems are unable to increase airflow. In addition, these portable units may include several of the technologies previously noted, such as HEPA or ULPA filtration, and air ionization. Portable units are easier to deploy and may be moved as need to accommodate changes within the workplace.

Applications of these technologies may be applied to various HVAC systems serving the workplace. Implementation of specific measures should be considered with goals, expectations and the specific systems to be applied, including:

Since coronavirus may be transmitted through respiration, touch and fecal-oral transmission, restrooms will require special attention. Though surfaces may be cleaned as previously noted and HVAC systems enhanced, additional measures are recommended to maintain functional restrooms for the workplace staff. The following strategies may be applied:

Bi-polar Ionization. For water closets without lids, lids would need to be added.

Spray disinfectant applied to bowl of water closet during and after each flush.

Use of personal toilet paper.

Hands free toilet fixtures.

Adopt procedures to minimize the dispersion of the virus in the restroom, such as limiting use of stalls with adjacent occupancy and closing lids when flushing toilets.

Utilize a bathroom attendant to wipe down all fixtures after each person uses the facilities.

Recent research findings now indicate that COVID-19 is not being found in water supplies.


Each day we learn more about the COVID-19 virus, how it behaves, and the best recommendations and strategies for dealing with it. We will continue to monitor and evaluate this information to present our latest insights and approaches on this matter. Our goal is to help you prepare your buildings for the safe and productive return of the workforce.

For reopening or returning to work assessment give us a call, we are standing by to help!

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