Is 70% Isopropyl Alcohol better at killing bacteria and viruses than 90% isopropyl alcohol?

The United States Centers for Disease Control and Prevention (CDC) did a research on disinfecting and sanitizing methods and published the Guideline for Disinfection and Sterilization in Healthcare Facilities.

70% isopropyl alcohol can cross over the cell membrane more effectively, thereby attacking the entire cell and killing the bacteria (CDC, 2020).

Benefits of 70% isopropyl alcohol: –

• Coagulation of surface proteins proceeds at a slower rate, thereby allowing the alcohol to enter the cell.

• 70% alcohol, being a dilution of absolute alcohol, contains water which is essential in the denaturing process of proteins.

• Due to the concentration difference of water and alcohol on either side of the cell wall, 70% alcohol enters the cell to denature both enzymatic and structural proteins. This increases the potency of its antimicrobial properties.

The CDC recommends 70% for disinfecting one’s household and routine cleaning (CDC, 2020).

https://www.cdc.gov/infectioncontrol/pdf/guidelines/disinfection-guidelines-H.pdf