Table 1. LLIN durability components.

Component	Definition	Test conducted	Outcome indicators	WHO criteria or industry standard
Attrition	Net loss from household through discarding or alternative use	Household survey	Net presence
Physical integrity	Physical state of the net to estimate bite protection	Count number, location, and size of hole(s) of a maximum 3 nets per household	Holed surface area measured by pHI [6] or MHSA (cm2)	pHI 0–64, MHSA ≤ 79 cm2: good
				pHI 65–642, MHSA 80–789 cm2: damaged
				pHI ≤ 642, MHSA ≤ 789 cm2: serviceable
				pHI ≥ 643, MHSA ≥ 790 cm2: too torn/unserviceable
Functional survival [6]	Estimation of nets still in households in serviceable condition	Median survival analysis	(Number of nets present and serviceable)/(number of nets originally received and not given away or lost to follow-up)	Median net survival in years = time point at which the estimate of functional survival crosses 50%
Biological efficacy	Ability of net to incapacitate or kill susceptible anopheline mosquitoes after contact with insecticide	IACT: whole nets [24]	Proportion of mosquitoes dead at 24 hours
			Proportion of mosquitoes not blood fed
		WHO cone/tunnel test: 25 × 25 cm pieces [13]	Net samples meeting optimal bioefficacy criteria	1-hour knock-down ≥ 95% or 24-hour mortality ≥ 80% or blood feeding inhibition ≥ 90%
Insecticide content	Amount of active ingredient in the net	Permethrin: GC-FID Deltamethrin: HPLC-DAD	Compliance of nets with WHO specifications at baseline; loss of active ingredient over time	Olyset: 20 g/kg ± 25% [15–25 g/kg] PermaNet: 1.4 g/kg ± 25% [1.05–1.75 g/kg] NetProtect: 1.8 g/kg ± 25% [1.35–2.25 g/kg]

GC-FID, gas chromatography with flame ionisation detection; HPLC-DAD, high-performance liquid chromatography with diode array detection; IACT, Ifakara Ambient Chamber Test; LLIN, long-lasting insecticidal net; MHSA, median hole surface area; pHI, proportionate hole index; WHO, World Health Organization.