Heathrow’s passenger numbers were down 89% year-on-year in July, figures published by the airport show.
Just 867,000 people travelling through the west London airport last month, compared with 7.754 million in July 2019.
The latest monthly data reflects a slight uplift in passenger traffic since the start of the coronavirus pandemic.
Demand was down 95% year-on-year during the previous month.
More than half of the passengers who used Heathrow in July were visiting European destinations, which mostly do not require people to go into quarantine on arrival.
Heathrow said 60% of its route network remains grounded and claimed the Government’s quarantine policy is “preventing the UK from travelling to and trading with these countries”.
It wants the 14-day self isolation requirement to be eased for people who test negative for coronavirus after arriving in the UK.
Heathrow chief executive John Holland-Kaye said: “Tens of thousands of jobs are being lost because Britain remains cut off from critical markets such as the US, Canada and Singapore.
“The Government can save jobs by introducing testing to cut quarantine from higher-risk countries, while keeping the public safe from a second wave of Covid.”