At what concentration is alcohol typically used for disinfection?

Alcohol is most commonly used for disinfection at a concentration of 70%. This concentration is optimal for antimicrobial activity because it has enough water content to facilitate the penetration of alcohol into the cell walls of microbes. When the alcohol concentration is too high, such as at 90% or above, it can actually cause the outer cell membranes of bacteria to harden too quickly, effectively sealing the bacteria and preventing the alcohol from entering the cell and killing it. A lower concentration, like 60%, may not be as effective since it does not provide sufficient alcohol to achieve an effective level of disinfection. Therefore, 70% alcohol is the standard recommendation for effective disinfection, properly balancing efficacy and the necessary conditions for microbial cell penetration.