Modern air conditioning was invented nearly 120 years ago by Willis Carrier. Air conditioning systems use a refrigerant to pull heat out of the air and dump that heat into the environment. In addition to cooling the air, the air is dehumidified. In fact, the original purpose of Carrier’s air conditioner was to remove moisture from the air in a printing factory.
In the face of the COVID-19 pandemic, much has been written about ways to combat both the pandemic and the economic and societal effects of the pandemic. Here are seven ways air conditioning provides economic and health benefits that can help combat the COVID-19 pandemic.
One of the health benefits of air conditioning that can directly impact the pandemic is air circulation. Without air circulation, air droplets from coughs and sneezes can hang in the air for up to three hours. Air circulation, however, dissipates air droplets, rendering them less likely to remain hanging where they can be inhaled.
Scientific studies have found that the most common and effective route for transmission of COVID-19 is through suspended air droplets. Because of this, inadequate ventilation has often been cited as a factor in indoor transmission. Air conditioning can improve indoor air quality by circulating air and dissipating suspended droplets that might carry the virus.
The volume of air circulation needed to dissipate air droplets has not yet been studied. However, many state air quality agencies recommend installing an HVAC system that can replace the air inside a confined space at least six times per hour. This means for a 1,000 square foot apartment, your air conditioning system should be capable of moving a volume of air on the order of 3,000 cubic feet per minute.
For a commercial building, the air conditioner’s capacity will need to be scaled accordingly. Fortunately, the formula is largely linear. This means that a 3,000 square foot office will need commercial ventilation services capable of moving about 9,000 cubic feet of air per minute.
Experts believe that poorly ventilated indoor spaces can promote the spread of coronavirus. However, this is because recirculated air can cause a build-up of coronavirus in ducts and the air. On the other hand, ventilation, specifically an HVAC design that brings outside air into an indoor space. As a result, one of the major health benefits of air conditioning is that it can vent potentially infected air outside and bring fresh air inside.
For residences, this means that the greatest health benefits of air conditioning come when the home’s windows are opened periodically to pull fresh air into the home. In climates where the heat is not too extreme, residents can crack open windows during the daytime to ventilate their house or apartment. In hotter climates, residents might be able to open windows at night to bring fresh air into the home.
Commercial property presents a more complicated problem. Many commercial buildings do not have outside windows that open. Windows in office buildings are sealed for safety reasons and to control heating and cooling costs. In the case of a commercial building such as a restaurant or shop with an exterior door, it may be possible to leave the exterior door open so that the air conditioning system can ventilate the interior space.
For shared commercial space, such as an office suite in a large office building, that does not have an exterior door, ventilation may be more difficult. However, leaving interior doors open to circulate throughout the office suite and out to the common areas may provide many of the health benefits of air conditioning.
Filtering air can provide some of the greatest health benefits of air conditioning because well-filtered air can help reduce concentrations of the virus when outside ventilation is not available. The most effective air filters available are high-efficiency particulate air (HEPA) filters. To receive HEPA certification, a filter must remove 99.97% of particulates 0.3 microns in diameter. This is about double the size of a virus. That is, viruses are about 0.125 microns in diameter.
However, viruses do not typically travel freely. Rather, they are carried on moisture droplets or even dust particles that are greater than 0.3 microns in diameter. Thus, a HEPA filter might not capture the virus itself, but it can capture whatever the virus is riding on.
Most commercial cooling and heating systems lack HEPA filtration as it wasn’t necessary before. As a result, you might need to upgrade your HVAC system to realize the full health benefits of air conditioning. Just keep a few things in mind:
- Cost: HEPA filters are usually more costly than standard air conditioning filters.
- Capacity: Because HEPA filters are designed to capture smaller particles, they also allow less air through. This means that your throughput will decrease unless you upgrade your air conditioning system.
- Compatibility: Not all air conditioning systems have compatible HEPA filters. You might need to upgrade your air conditioning system to replace the stock filters with HEPA filters.
- Installation: You might need to hire a company that provides HVAC services to install HEPA filters. Improperly installed HEPA filters can be ineffective for capturing particles if gaps allow air to bypass the filter material.
Keep in mind that if you rely on your air conditioning system to protect against the spread of COVID-19, you will likely require regular maintenance of your system to maximize the health benefits of air conditioning. For example, HEPA filters need to be changed regularly to maintain airflow, remove captured pollutants, and reduce the risk of recirculating dirty or infected air.
Moreover, during the COVID-19 pandemic, caution should be used when changing air filters. Virus DNA and RNA have been found on used filters and it is not known whether this is enough to infect someone with coronavirus.
Therefore, you should consider hiring an HVAC technician to change your filters and ensuring that the technician turns the system off before changing the filters so none of the captured particles get released into the air. Moreover, the technician should wear a respirator while changing the filters and place the filters inside a plastic bag for disposal.
While your commercial HVAC maintenance company changes your filters, you should consider having the technician clean your vents and ducts. Dust and moisture particles that carry viruses can deposit the germs on the surfaces of your ducts and vents before they can be captured in the filters. Regularly cleaning and disinfecting vents and ducts can ensure that all occupants realize the health benefits of air conditioning.
As previously mentioned, air conditioning was originally used to control the humidity in printing plants. As an HVAC system cools or heats the air, it can also add or remove humidity. Some of this occurs naturally as a result of cooling or heating the air. Cooler air has a lower capacity for water vapor than warmer air.
However, HVAC contractors can add a humidifier to an HVAC system to control the exact amount of moisture in the air. In the case of coronavirus, humidifiers can support the health benefits of air conditioning because viruses generally spread better in dry air than in moist air.
This might seem counter-intuitive given that viruses usually ride on air droplets when they pass from one person to another. However, humid air can cause air droplets to grow large enough that they sink rather than float on air currents.
Moreover, the cilia in the nose and throat do not function as well when they are dry as when they are moist. This means that they can fail to capture the droplets and allow them to enter the lungs where they can cause an infection.
Finally, the lungs are less likely to cough or sneeze in dry air as in moist air. This is the reason that a humidifier is often helpful to keep your lungs clear when you have the common cold.
These health benefits of air conditioning come primarily with a humidifier installed with the system by a technician that specializes in cooling and heating services. That is, most HVAC systems do not include humidity control. Rather, this is often an add on to an HVAC system that is installed when the HVAC system is installed or as an aftermarket modification.
Clean the Air
In addition to the filtering system that is built into the air conditioning system, you can consider additional air cleaning systems. For example, portable air cleaners use filters or static electricity to remove additional dust and other particles from the air.
Specifically, these devices draw air through an air passage and force it through a HEPA filter or past electrically charged panels to remove particles from the air. To the extent these particles carry the virus, these portable systems can be helpful to enhance the health benefits of air conditioning.
Additionally, HVAC systems can be supplemented with air cleaning systems to further remove particles and even the viruses themselves from the air. For example:
- Pre-filters: Some businesses that are particularly concerned about contamination use specialized pre-filters to capture particles before they enter air conditioning systems. These maximum efficiency reported value (MERV) filters are intended to clean the air beyond the typical HEPA filter. For example, a MERV 15 filter is commonly used in hospitals to remove airborne bacteria and a MERV 19 filter is typically used in pharmaceutical manufacturing to filter viruses out of the air.
- Ultraviolet (UV) light: UV light is particularly good at killing bacteria and viruses. Hospitals use HVAC designs that incorporate UV lamps to sterilize the air passing through their HVAC systems. UV light can improve indoor air quality by supplementing the effectiveness of filters and humidity control when used properly.
It should be noted that the U.S. Environmental Protection Administration (EPA) has warned against using ozone generating air purifiers. These air purifiers deliberately generate ozone, which is a form of oxygen with three oxygen atoms bonded together. It has an electric charge, which makes it very effective at binding to mold spores and odor molecules.
However, ozone is a pollutant that can cause long term health damage to your skin, eyes, lungs, and other exposed body parts. Worse yet, ozone-generating air purifiers do not remove viruses and bacteria from the air. The danger of ozone combined with its ineffectiveness against coronavirus mean that ozone generators do not provide any of the health benefits of air conditioning.
Combine Multiple Measures
Hospitals have been using air conditioning to make their air safe for decades. Instead of focusing on a single part of the air conditioning system, hospital systems use multiple processes in combination to reduce the pathogens in the air. This is both cost-effective and mathematically efficient.
Think of it this way — a high-end cleanroom system might remove 99.97% of airborne pathogens but cost millions of dollars. However, a standard system with HEPA filters supplemented with UV light, MERV pre-filters, and a humidifier might be nearly as effective at a fraction of the cost. For most homes and businesses, this might be more than adequate to protect residents, employees, and customers without breaking the bank.
A secondary effect of the COVID-19 pandemic has been a severe drop in economic activity of businesses and individuals. This drop has been the result of a combination of business shutdowns, stay-at-home orders, and a reluctance of consumers to engage in their pre-pandemic activities. As a result, movie theaters, casinos, hotels, airlines, restaurants, and amusement parks have suffered and even gone out of business.
Thus, in addition to the health benefits of air conditioning, HVAC systems also provide substantial economic benefits necessary to combat the COVID-19 pandemic. In fact, air conditioning has long been viewed as an economic generator.
Since 1960, 60% of America’s economic growth can be attributed to air conditioning. This is particularly true in the South and West where air conditioning made living and working comfortable year-round. For proof of this, just consider the difficulties of working indoors during the summer in Florida or Arizona before the invention of air conditioning.
During the pandemic, this economic activity is critical to economic recovery. The summer and fall months, typically the hotter, drier months of the year, require air conditioning in much of the U.S. Air conditioning makes economic activity during this critical time possible.
More importantly, by using the systems and techniques for using air conditioning to clean the air, businesses can assure customers that their risk of infection remains low. When combined with face masks and social distancing, air cleaned with an air conditioning system might provide a way to open some of the more deeply affected businesses like movie theaters and casinos.
The economic and health benefits of air conditioning during the pandemic cannot be overstated. Since the virus is airborne, any steps that can be taken to circulate and ventilate the air can help reduce the risk of infection. But additional steps can be taken to improve the effectiveness of air conditioning to combat COVID-19. Using filters and pre-filters, UV lights, and humidifiers with an HVAC designed to replace the air in the space at least six times per hour can provide an effective and efficient way to protect the health of your employees and customers. This will allow your business to reopen with confidence.