top of page

Outdoor air gets a clean term, find out what ECA means.

The importance of indoor air health is expanding. So too, is new technology supporting the healthy air revolution. Recently, air health, ventilation, and pathogen transmission experts have coined a new term, Equivalent Clean Airflow, or ECA, describing how well air is cleaned and circulated within a space. Essentially, ECA measures the efficacy of how air within a space is cleaned and cleared, ECAi measures the safe number of occupants based on its cleanliness.

Cleaning, in this instance, is not a rag and spray bottle, but instead, filters (in HVAC, air purifiers, etc) and/or the introduction of outdoor air.

Equivalent clean air refers to the concept of providing indoor spaces with ventilation or disinfection solutions that mimic the quality and characteristics of clean outdoor air.


Why is ECA important?

When outdoor air is brought into a building, it undergoes filtration, conditioning, and sometimes treatment processes to meet specific indoor air quality standards. The goal is to remove pollutants, particulate matter, and contaminants while adjusting the temperature and humidity levels to create a comfortable and safe indoor environment.

Equivalent clean air can be achieved through various ventilation systems, such as natural ventilation, mechanical ventilation, UVC or any combination of these. Natural ventilation relies on openings like windows, doors, or vents to allow outdoor air to enter and circulate through the building. Mechanical ventilation, on the other hand, uses fans, ducts, and air-handling units to distribute and control the flow of outdoor air.

How does exhalation impact ECA?

When people occupy a space, the amount of exhalation brings potential pathogens into the air and therefore increases the need for greater airflow (air changes). This new term is called Equivalent Clean Air, measuring the amount of clean air needed to clear the air based on the number of people in the room.

Why not just use the term EOA (Equivalent Outdoor Air)?

EOA is a term that has been used in the industry for a while, but some concern exists in assuming the outdoor air is clean. For example, some areas have very harmful outdoor air during wildfire season. Ensuring we are not introducing toxins to our indoor air is very important to our overall indoor health. Also, clean air can come from inside air (that has already been heated or cooled) and "cleaned" by filters, UVC or other approved methods.

How does a high or low ECA impact occupants?

By providing equivalent clean air (ECA), indoor spaces can minimize the buildup of pollutants, remove airborne pathogens, and maintain an overall healthier indoor environment. This is especially important in buildings where the windows cannot be opened or in areas with poor outdoor air quality due to pollution, allergens, or extreme weather conditions.

How do you measure ECA?

ECA is a mathematical equation based on airflow, systems, and even air particles. While it seems complicated, digital testing makes the process easy and gives real-time results, allowing you to make system adjustments, try scenarios and settings to help you know how to most efficiently meet your indoor air cleanliness goals and building standards.

Understanding the scientific side of ECA requires precise understanding of how very small particles (micron level) move and potentially stay in the air, this level of identification requires lab testing or lab grade testing done outside of a lab to get accurate ECA results. Some ECA testing products test digitally but may lack precise findings and/or consistency due to the level of analysis and/or inclusion of filtration in the testing method. BreatheScore Certify is the only system that gives you real time results, because it is fully digital in measurement and analysis, measuring air tracer dilution in real-time.

This method of air tracer and particle analysis provides dramatic savings, as tests can be done in as little as 20 minutes per 5,000 sqft. A ten-story building can be tested in a single day.

We work with property owners, workplaces and HVAC/TAB service providers to empower an air change revolution.

Learn more about BreatheScore Certify, the most cost-effective and accurate way to measure clean indoor air, provides digital solutions for measuring ECA (as well as eACH).


bottom of page