The waste crisis erupted in 2015 when the Lebanese authorities closed the main landfill site near Beirut, having arranged no alternative.
The open burning of waste in Lebanon poses serious health risks, Human Rights Watch warned in a report released on Friday, blaming decades-old, across the board government failure.
The New York-based watchdog said the crisis, which escalated in 2015 when waste management largely collapsed across Lebanon, was a particular threat for children and old people, and constituted a rights violation.
"Open burning of waste is harming nearby residents' health one garbage bag at a time, but authorities are doing virtually nothing to bring this crisis under control," said Nadim Houry, HRW's interim Beirut director.
Rivers of rubbish flooding populated areas across the country, including in central Beirut, put the spotlight on Lebanon's waste problem but the rights group said a silent crisis had been unfolding elsewhere for years.
"In the 1990s, the central government arranged for waste collection and disposal in Beirut and Mount Lebanon but left other municipalities to fend for themselves without adequate oversight, financial support, or technical expertise," HRW said.
The report, entitled "As If You're Inhaling Your Death", said that led to a massive increase in open burning of waste across the country.
It quoted research by the American University of Beirut that found 77 percent of Lebanon's waste is improperly dumped or landfilled when only 10 to 12 percent is considered impossible to compost or recycle.
HRW said the "vast majority" of the more than 100 residents living near open dumps whom its researchers interviewed suffered from respiratory problems.
The report said that besides its failure to set up a nationwide waste management programme, the government was doing nothing to prevent open burning, to monitor its impact and inform the population of the risks.
The watchdog said those combined failures "violate Lebanon's obligations under international law, including the government's duties to respect and protect the right to health".