Perception of a chronic volcanic hazard: persistent degassing at Masaya volcano, Nicaragua

Table 3 Gas exposure guidelines and maximum values found at Masaya

Gas	Exposure guidelines (μg m⁻³)		Source	Maximum recorded concentration (μg m⁻³)	Distance from vent (km)
Gas	Time	Limit	Source	Maximum recorded concentration (μg m⁻³)	Distance from vent (km)
SO₂	10 minutes	500	WHO^a	471	6.34
	24 hours	20	WHO^a
	24 hours	365	Nicaragua^b
	Annual	50	WHO^c
	Annual	80	Nicaragua^b
HCl	1 hour	750	UK^d	40.0	6.34
HF	Monthly	160	UK^e	7.65	6.34
NO₂	1 hour	200	WHO^a	14.0	7.12
	1 hour	400	Nicaragua^b
	Annual	40	WHO^a
	Annual	100	Nicaragua^b
HBr	1 hour	700	UK^e	4.13	35.0

Sources: ^aWHO ([2006]), ^bMARENA ([2002]) ^cWHO ([2000]) ^dDEFRA ([2006]) ^eDEFRA ([2009]).

ISSN: 2191-5040