Table 2:

Guidelines for indoor PM_2.5 by the international organizations

*Organization*	*Remarks*	*Limit Values for PM_2.5 (μg m⁻³)*	*Reference*
WHO	24-hours	15	(8)
WHO	annual	5
Health Canada	1-hour	100	(9)
Health Canada	long-term	40
US EPA	N/A	N/A	-
EU	N/A	N/A	-

^*Note: N/A means not available