Gaseous elemental mercury emissions from informal E-Waste recycling facilities in Pakistan

Detrimental effects of mercury (Hg) on ecosystems and human health have been well-documented. Whereas emissions of gaseous elemental mercury (GEM) from e-waste recycling have been reported in developed countries, much less is known about the situation in the Global South. Using a total of 132 passive air samplers, seasonally resolved concentrations of GEM in air were measured continuously at 32 informal e-waste recycling facilities and background location in Pakistan for a period of one year between September 2020 and December 2021. Annual average GEM concentrations at the studied locations ranged from 1.8 to 92 ng m^-3. Among the studied cities, higher concentrations were measured in Karachi (mean ± s.d: 17 ± 22, range: 4.2-92 ng m^-3), Lahore (16 ± 4.2, 8.2-22 ng m^-3) and Peshawar (15 ± 17, 4.9-80 ng m^-3), while lower levels were measured in Hyderabad (6.9 ± 6.2, 3.1-25 ng m^-3), consistent with a higher rate of informal recycling activities in metropolitan areas. Seasonally, higher GEM levels occurred during autumn (15 ± 16: 3.3-92 ng m^-3) and summer (13 ± 8.7: 1.8-80 ng m^-3) than in winter (12 ± 8.4: 2.5-49 ng m^-3) and spring (9.2 ± 7.3: 1.8-80 ng m^-3), possibly reflecting enhanced volatilization at higher temperatures and/or varying magnitude of recycling operations in different seasons. Policies and strict regulations related to e-waste management should be developed and implemented urgently in the country.