Benzene is an important chemical, but toxic in nature. It is primarily used as an intermediate to make other chemical products including plastics, rubbers, dyes, lubricants, glues, paints which can be found in the synthetic interior of cars. It is also present in vehicle emissions, cigarette smoke and gasoline.
According to the World Health Organisation, there is no safe exposure for airborne benzene but OSHA in the US sets a permissible long-term exposure limit to 1ppm per 8 hour day (based on 40 hours a week), and a short-term exposure limit of 5 ppm for 15 minutes.
The lab test
We tested 1 gram of activated carbon from a new car purifier with 1 gram from a car purifier used for just over 4 months.
Our test report on the used car purifier showed that 1 gram of activated carbon adsorbed 978 ppm of benzene fumes - as well as other VOCs (volatile organic compounds) not tested.
We can put this into perspective using the OHSA exposure limit above, by breaking it down as follows:
The box was used for 113 days and there are 50g of activated carbon per car purifier so 50g x 978ppm divided by 113 days. This result shows the used car purifier had adsorbed 433 ppm per day /18 ppm per hour / 4.5 ppm per 15minutes.
If the driver was in the car for more than 15 minutes over a period of 4 months without this car purifier, they would have been inhaling toxic amounts of benzene.
It is important to note that this test was simply based on the adsorption of benzene - external influences are not taken into consideration, as these factors aren't standard and can't be controlled. The following are just a few examples of what can impact the number of VOCs in your car:
• Air pollution • Temperature • Relative Humidity • City or countryside • Traffic conditions • Age and type of car • Fuel type
Testing notes: The product we tested had the following parameters: Used in India in rural and semi-urban locations during the summer months. Driver was a non-smoker, and the car was 3 years old.
Learn more about Airbon and Activated Charcoal
Benzene test report on a used Airbon box