1. Are Car Air Purifiers Even Necessary?
Previous car air purifier tests we ran showed that the built-in air filters in most cars do a good job of removing particulate pollution like PM2.5 when the car is set to ‘recirculate mode’. If the purpose of buying a car air purifier is to reduce cabin pollution like PM2.5, dust, and pollen, then using your car’s own fan can be surprisingly effective. Just make sure to replace the filters every few months.
However, if VOCs and gases from other cars’ exhaust (e.g. when sitting in a traffic jam) are what you are concerned with, then the filters in most cars won’t be able to trap them. For this, you may want a standalone air purifier with an activated charcoal filter.
2. Do Air Purifiers Lower the Risk of COVID-19 Spread?
If reducing virus transmission is the main objective of purchasing a car air purifier, then an air purifier can add an extra layer of protection. HEPA air purifiers are proven tools to reduce virus and COVID-19 spread.
A study by the CDC showed concrete evidence that HEPA air purifiers reduce COVID-19 spread indoors. Using an air purifier with other proven tools such as masks and improving ventilation (opening windows) could help reduce the risk of COVID spread.
3. What is the Best Car Air Purifier for COVID-19?
The best car air purifier for COVID-19 is a HEPA air purifier. HEPA filter air purifiers are highly effective at filtering out particles the same size as COVID-19. Air purifiers with HEPA filters, therefore, are the best car air purifiers on the market. There is no need to buy an air purifier specifically marketed as a “car air purifier”, any HEPA filter will do the job.
In addition, the ideal air purifier is portable and compact. A car air purifier needs to be portable by either being battery operated or having USB charging so it can easily be used in the car.
If VOCs and exhaust fumes from other cars are the main concern, then an air purifier with an additional activated carbon filter is best. Some air purifiers include both a HEPA filter and an activated carbon filter, and therefore can protect against both forms of pollution in the car.
4. What Air Purifiers Are NOT Recommended for Cars?
Air purifiers with UV lights and ionizers are not recommended for cars. Data shows that ionizers can actually create air pollution and may pose an additional health risk for passengers. They also add to the overall cost of the purifier.
5. What Clean Air Delivery Rate (CADR) is Needed For a Car Air Purifier?
The ASHRAE’s recommended number of air changes per hour for “airborne infection isolation rooms” is 12 air changes per hour (ACH). This is a conservative value, and a good guide for an enclosed, small space such as a car cabin. Knowing that most car cabins measure approximately 3 cubic meters in volume, a car air purifier would need a Clean Air Delivery Rate (CADR) of 36 m3/hr.