Evaluating the Effectiveness of a Commercial Portable Air Purifier in Homes with Wood Burning Stoves: A Preliminary Study

Wood burning for residential heating is prevalent in the Rocky Mountain regions of the United States. Studies have shown that wood stoves can be a significant source of PM2.5 within homes. In this study, the effectiveness of an electrostatic filter portable air purifier was evaluated (1) in a home where a wood stove was the sole heat source and (2) in a home where a wood stove was used as a supplemental heat source. Particle count concentrations in six particle sizes and particle mass concentrations in two particle sizes weremeasured for ten 12-hour purifier on and ten purifier off trials in each home. Particle count concentrations were reduced by 61–85 percent. Similar reductions were observed in particle mass concentrations. These findings, although limited to one season, suggest that a portable air purifier may effectively reduce indoor particulate matter concentrations associated with wood combustion during home heating.

Effectiveness of Colors used on Safety and Health Signs for Communicating Severity of Injury

Signs are used extensively in workplaces and on products to identify hazards and provide instructions for appropriate behavior. A fundamental element of these signs is the signal-word panel located at the top of the sign. The colors and words in this panel are intended to convey information about the hazard identified. One type of hazard information concerns the severity of injury/illness associated with the hazard. The standard of the American National Standards Institute (ANSI) for facility signs uses three severity categories: 1) death or serious injury, 2) minor or moderate injury, and 3) property damage. The standard specifies which signal-word panel format, including color, to use based in part on the severity category. The purpose of this study was to determine if college students associate color with severity. The sample population consisted of 59 students tested in nine small groups. Twelve signs were shown to them in random order. Five of the signs had a color for the background of the signal-word panel. The colors were red, orange, yellow, blue, and gray. The signal word was a nonsense word and the text panel contained repetitions of the letter x in sentence format. Subject rated their impressions of the colors using two ordered rating scales for severity. Results indicated that color had a highly significant effect on severity ratings. Median ratings were generally consistent with the ANSI standard, except for orange. Red rated highest on both scales. Blue and gray rated lowest. Yellow and orange were in between red and blue. According to the ANSI standard, orange should indicate the same severity as red. These results indicated that orange was associated with less severity than red. Apparently, the ANSI standard's use of orange to identify a hazard associated with death or a serious injury is questionable.