Figure 5From: Particulate matter (PM) 2.5 levels in ETS emissions of a Marlboro Red cigarette in comparison to the 3R4F reference cigarette under open- and closed-door condition Climate parameters during ETS measurement – relative humidity. a) indoor relative humidity; b) outdoor relative humidity; red: Marlboro Red; blue: 3R4F reference cigarettes; values are averages for the total time interval.Back to article page