CDC offers a perspective on how to deal with automobiles and vehicle HVAC amid the COVID-19 threat

Steps like a “blow out” could help a collision repair shop or other automotive professional reduce the risk of COVID-19 through a vehicle HVAC system, a spokeswoman for the Centers for Disease Control wrote on Monday.

CDC press secretary Donnica Smalls discussed methods of treating a vehicle that was brought into the automotive aftermarket at the request of Repairer Driven News last week.

The CDC has provided guidance to drivers of ride-sharing, grocery delivery and non-emergency vehicles on cleaning and disinfecting vehicles during the pandemic. However, no specific vehicle handling information has been published for hundreds of thousands of automotive professionals across the country.

The Mobile Air Conditioning Society last month asked the Environmental Protection Agency, CDC and Occupational Safety and Health Agency for guidelines on cleaning vehicles during the COVID-19 coronavirus pandemic, highlighting the “unique challenge” their interiors pose bring.

“Each vehicle cabin is a small, self-contained, climate-controlled environment that restricts movement, requires close occupant contact and repeated internal touches,” wrote Andy Fiffick, CEO of MACS, in an April 20 letter to the EPA. (MACS stated that similar messages were sent to the CDC and OSHA.)

Fiffick also raised concerns about a vehicle’s HVAC system.

“The air conditioning system in vehicles presents different challenges compared to a residential environment,” he wrote. “The operation of the system enables the selection of 100% outside air (outside air) and circulating air in the cabin. In recirculation mode, the system A / C designs can vary for the amount of outside airflow. The number of air changes per hour can be less than many household applications. Typical industrial requirements for a house are in the range of 4 to 6 air exchangers per hour. Some mobile A / C systems that operate in max cooling mode (recirculation) have provided at least 6 changes per hour.

“The speed of the airflow directed at the occupants is usually much faster than in residential systems.”

The CDC also mentioned the HVAC system in its guidance for passengers and other commercial passenger drivers.

“Avoid using the air recirculation option to ventilate the vehicle during passenger traffic. Use the car’s vents to let in fresh outside air and / or lower the vehicle windows, ”the CDC told passengers on April 17, 2020.

We had asked all three agencies to comment on the trade group’s inquiry.


On Monday, Smalls pointed out that the CDC has also not issued specific advice on home HVAC systems.

“Regarding the cleaning and / or maintenance of automotive ventilation systems, it should be noted that CDC has not published guidance on the decontamination of HVAC systems in buildings (including air filtration systems) that may be exposed to SARS-CoV-2.” She wrote. “So far we have not found corroborative evidence that viable viruses contaminate these systems. Should such systems actually become contaminated with viable viruses, it is believed that the most likely scenario is that the virus will naturally lose its viability within hours to days. Therefore, there are no guidelines advocating proactive system shutdowns for decontamination and / or filtering replacement. “

Repair shops with concerns could follow a three-step process, wrote Smalls.

If there is reason to assume that a vehicle ventilation system was contaminated with SARS-CoV-2, based on current knowledge, it is assumed that the following suggestions offer improved protection for workers from exposure:

1. Whenever possible, a 24 hour wait that maximizes exposure to sunlight increases the likelihood that previously generated viruses will be disabled.

2. Perform a “blow out” ventilation system by carefully positioning the vehicle outdoors, setting the heater to the maximum temperature, ensuring that the system is not in recirculation mode, and then running the fan motor at maximum setting for approx. 5 minutes with the running car empty, doors open and windows down. (Note: Partial disinfection of the vehicle interior may be required to allow safe adjustment of vehicle displacement and ventilation system settings.)

3. After the waiting time has expired and / or the system has been blown out, start the surface disinfection of the vehicle interior according to the disinfection instructions …

It is assumed that no further cleaning or maintenance of the vehicle ventilation system is required. If active virus particles have been captured on a cabin air filter or otherwise in the ventilation system, there is no known reason to believe that they will not stay there and lose their remaining viability within hours to days of being captured. (Minor formatting changes.)

Vehicle interior

Regarding the disinfection of the vehicle interior, Smalls wrote:

CDC will continue to make recommendations based on the best available science to help people make choices that will improve their health and safety. In addition to the preliminary guidelines for businesses and employers, here are general guidelines for cleaning and disinfecting vehicles that may be useful for those in the auto repair industry:

• Clean hard, non-porous surfaces inside the vehicle such as hard seats, armrests, door handles, seat belt locks, light and air controls, doors and windows and handles with detergent or water and soap. The surfaces are visibly soiled before the disinfectant is applied. To disinfect hard, non-porous surfaces, suitable disinfectants include:

° EPAs registered antimicrobial products for use against the novel coronavirus SARS-CoV-2, the virus that causes COVID-19. Follow the manufacturer’s instructions on concentration, method of application, and contact time for all cleaning and disinfecting products.

° Diluted household bleach solutions prepared for disinfection according to the manufacturer’s label, if suitable for the surface. Follow the manufacturer’s instructions for use and proper ventilation. Make sure the product has not passed its expiration date. Never mix household bleach with ammonia or any other detergent.

° Alcohol solutions with at least 70% alcohol.

• For soft or porous surfaces such as cloth seats, remove any visible contamination, if any, and clean them with the appropriate detergents specified for use on those surfaces. After cleaning, use products that are EPA approved for use against the virus that causes COVID-19 and are suitable for porous surfaces.

• Remove from frequently touched electronic surfaces such as B. tablets or touchscreens used in the vehicle, visible dirt and then disinfect according to the manufacturer’s instructions for all cleaning and disinfecting products. If manufacturer guidelines are not available, consider using alcohol-based wipes or sprays that contain at least 70% alcohol for disinfection.

Gloves and other disposable personal protective equipment (PPE) used to clean and disinfect the vehicle should be removed and disposed of after cleaning. Immediately after removing gloves and other PPE, wash your hands with soap and water for at least 20 seconds, or use an alcohol-based hand sanitizer with at least 60% alcohol if soap and water are not available. If disposable clothing has not been worn, work clothing / clothing worn during cleaning and disinfection should then be washed on the warmest suitable water setting and items should be dried completely. Wash hands after handling laundry. (Minor formatting changes.)

As mentioned above, the CDC may revise this or issue specific instructions for the auto repair industry. Stores may want to keep an eye on the agency’s COVID-19 CDC Businesses and Workplaces and Transportation and Delivery portals.

“CDC will continue to make recommendations based on the best available science to help people make choices that will improve their health and safety,” Smalls wrote on Monday.

The EPA and OSHA Labor Department also issued replies last week.

“The EPA has received the letter and will coordinate a response with the CDC and other federal agencies if necessary,” an EPA spokesman wrote in an email.

The agency also pointed out that it and the CDC have issued new cleaning guidelines for all Americans, including businesses.

“OSHA has worked to educate and protect the public, coordinate efforts with other agencies and stakeholders, and consistently provide resources, guidance and information through various media,” a Labor Department spokesman said in a statement. “The department has and develops guidelines for protecting workers in various industries. Certain safety guidelines apply to every workplace and employers should adapt infection control strategies based on a thorough risk assessment and use appropriate combinations of technical and administrative controls, safe work practices and personal protective equipment to prevent worker exposure. As stated in OSHA’s Guidelines on Preparing Workplaces for COVID-19, employers and workers should implement basic infection prevention measures by following regular cleaning practices, including routine cleaning and disinfection of surfaces, equipment, and other elements of the work environment. “

More information:

“Ask the experts – how professional restorers deal with the disinfection of vehicles”

Society of Collision Repair Specialists, April 28, 2020

Letter from the Mobile Air Conditioning Society to the Environmental Protection Agency

MACS, April 20, 2020

CDC COVID-19 portal “Companies and jobs”

CDC COVID-19 portal “Transport and Delivery”

CDC Master COVID-19 Coronavirus Portal

Environmental Protection Agency “List N” of COVID-19 disinfectants

Joint EPA and CDC guidelines on cleaning and disinfecting COVID-19

EPA COVID-19 portal

COVID-19 portal of the health and safety authority


An entrance sign for the Centers for Disease Control in Atlanta, Georgia is seen on the Emory University campus on August 28, 2011. (sshepard / iStock)

A CDC billboard is seen in San Jose, California on March 13, 2020. (Andrei Stanescu / iStock)

The CDC provided some advice on May 4, 2020 about how to deal with a vehicle HVAC system that may be exposed to the COVID-19 coronavirus. (deepblue4you / iStock)

“Avoid using the air recirculation option to ventilate the vehicle during passenger traffic. Use the car’s vents to let in fresh outside air and / or lower the vehicle windows, ”the CDC advises passengers as of April 17, 2020 as a precautionary measure for COVID-19 coronaviruses. (ponsulak / iStock)

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