A higher concentration works for a longer time, but anything over 50% DEET does not provide longer protection.

Source: https://www.bostonherald.com/2023/08/08/how-to-choose-an-insect-repellent-for-your-child/

EPA-registered repellent such as those containing DEET, picaridin, IR3535, oil of lemon eucalyptus, para-menthane-diol or 2-undecanone.

Source: https://www.eyeonannapolis.net/2023/08/mosquito-spraying-this-weekend-after-west-nile-virus-detected-in-severn/

REPEL – Use insect repellent that has ingredients approved by the EPA such as DEET, IR 3535, and Oil of Lemon Eucalyptus.

Source: https://iecn.com/west-nile-virus-cases-reported-in-rialto-san-bernardino/

So if you want to avoid being bitten, spraying yourself with tropical repellents such as DEET (diethyltoluamide), and wearing long sleeves and trousers should help prevent bites - though admittedly, this is easier said than done during a heatwave!

Source: https://www.gazettelive.co.uk/news/teesside-news/itching-teessiders-eaten-alive-mosquitoes-27690859

The public is further advised to use approved mosquito repellants containing DEET, Icaridin, or IR3535, and according to the product’s instructions.

Source: https://www.bahamaspress.com/16-cases-of-dengue-confirmed-as-public-urged-to-take-heed/