Filter and flow: Learn more about air circulation on our buses

Filter and flow: Learn more about air circulation on our buses

Here’s some refreshing info that will help you breathe easy while riding Community Transit: there is excellent air circulation and ventilation on our buses to help reduce the spread of COVID-19.

We know that one of the main ways COVID-19 spreads is through respiratory droplets in the air when an infected person coughs, sneezes or talks. Outside those droplets quickly dissipate, but indoors when there is poor ventilation, they can accumulate.

So, what about the bus, which is an indoor space but frequently open to the outdoors? How safe is it and what’s being done to keep the air moving? We have answers.

Airflow & filters

Along with vaccinations and face coverings, airflow and air filtration offer an added layer of protection for people riding on our buses and in vanpools.

Even with the windows closed, the air inside of buses is exchanged with fresh air about every five minutes. As weather allows, drivers and riders may also open windows for additional air circulation. Doors opening and closing at each stop also increase airflow on buses.

In addition to natural airflow, every bus in Community Transit’s fleet has a heating, ventilation, and air conditioning (HVAC) system that helps move air throughout the cabin of each vehicle.

Filters in HVAC systems help filter particles from the air. These filters are rated by their Minimum Efficiency Reporting Value, or MERV, on a scale from 1 to 16. The higher the MERV rating, the better the filter is at trapping specific sizes and types of particles.

Community Transit upgraded to MERV 7 filters on all buses in late 2020, the highest-rated filter currently available for installation with our HVAC systems.

What can be filtered out?

So, why not use the highest-rated MERV filters available? More filtration can reduce the rate of airflow in an HVAC system. If you’ve ever tried to blow out a candle with a mask on, you’ll know that it takes more force to move air through your mask. Picking the right MERV filter is about finding the right balance between air filtration and airflow within an HVAC system.

So, what does the MERV 7 rating mean when it comes to filtering the virus from the air on buses?

Viruses are incredibly small compared to many of the other particles that may float through the air we breathe. Research shows that the particle size of SARS-CoV-2 (the official name of the COVID-19 virus) is around 0.1 micrometer. For comparison, the average human hair is about 70 micrometers in diameter — 700 times that of the virus. However, viruses generally don’t travel through the air by themselves, but through respiratory droplets that are much larger than an individual virus. Most of the respiratory droplets and particles exhaled during talking, singing, breathing, and coughing are less than 5 micrometers in size. MERV 7 filters can help filter out many of the particles that may carry the virus.

Ready to ride?

With our region’s increasing vaccination rate, there will be more and more opportunities for our communities to be on the move. Community Transit is offering free rides to local vaccination sites through the end of July. Community Transit is here to get you to your destination safely. Be ready for a breezy ride, and remember that masks are still required on all Community Transit buses and vans. If you don’t have a mask to wear, Community Transit can provide you with one during your ride.

With proper precautions, people can breathe easy knowing that taking public transit is a safe option for travel. You can read about the many steps taken to protect riders and drivers, and how you can help keep others safe when riding Community Transit.

Tags: safety, covid-19