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SHS transfer in MUH
<br />the home, including the health effects associated with such ex-
<br />posure, remains significant. Americans spend nearly 69% of
<br />their time in personal living spaces (Klepeis et al., 2001), and the
<br />adverse health effects associated with SHS are intensified with
<br />increasing length of exposure (Davis, 1998). Moreover, SHS
<br />exposure in the home has been linked to an increased risk of
<br />heart disease and lung cancer in nonsmokers (USDHHS), and
<br />metabolites of tobacco -specific lung carcinogens attributable to
<br />SHS have been observed in nonsmokers with a spouse who
<br />smokes (Anderson et al., 2001).
<br />Nonsmokers who reside in multiunit housing (MUH) do
<br />not have the same level of control over exposure to SHS as those
<br />who live in single -unit housing, since they may share the same
<br />air space as those who smoke in adjacent units. Measurements
<br />of ventilation and infiltration systems in MUH show that a sig-
<br />nificant fraction of air entering living units originates from else-
<br />where in the building (Hewett, Sandell, Anderson, and Niebuhr,
<br />2007; Repace, 2007). Moreover, almost all respirable suspended
<br />particulates (RSP) emitted from burning cigarettes are less than
<br />2.5 µm in diameter (PM25), which are easily inhaled into the
<br />lungs (Klepeis, Apte, Gundel, Sextro, and Nazaroff, 2003)
<br />and capable of infiltrating through building cracks (Liu and
<br />Nazaroff, 2003; Thatcher, Lunden, Revzan, Sextro, and Brown,
<br />2003). Furthermore, even brief exposure to SHS can have ad-
<br />verse effects on nonsmokers, especially those with preexisting
<br />respiratory and cardiac conditions (Institute of Medicine,
<br />2009). Specific effects of brief exposure include sustained vascular
<br />injury (Heiss et al., 2008) and irritation of the eyes and nasal
<br />passages (Junker, Danuser, Morn, and Koller, 2001).
<br />To date, few studies have quantitatively assessed indicators
<br />of SHS exposure in homes. Leaderer and Hammond (1991) first
<br />investigated PM, in relation to SHS in 96 separate residences
<br />and found that levels in smoke -permitted homes (44 gg/m5)
<br />were 3 times greater than levels in smoke-free homes (15 µg/m3).
<br />In a subsequent review, Wallace (1996) found that levels in
<br />smoke -permitted homes were between 25 and 47 µg/m3 higher
<br />than those observed in smoke-free homes. In addition, Van
<br />Deusen et al. (2009) examined PM25 levels within 13 personal
<br />residences, 6 of which were single-family homes and the
<br />remaining 7 of which were within multiunit buildings. The
<br />authors observed elevated PM2 5 levels in both smoke -permitted
<br />and smoke-free areas within the assessed homes, which suggests
<br />that the confinement of smoking to certain areas of the home
<br />does not offer protection from SHS exposure. Most recently,
<br />Kraev, Adamkiewicz, Hammond, and Spengler (2009) assessed
<br />vapor phase nicotine in MUH and found detectable levels of
<br />nicotine contamination in 89% of smoke-free units. Although
<br />the latter study suggests that tobacco smoke contamination is
<br />not limited to only smoke -permitted units, the study design did
<br />not allow for an assessment of real-time transfer between units.
<br />To date, no single compound has been identified as a valid
<br />indicator for every constituent of SHS. However, there are cer-
<br />tain environmental markers, which are sufficiently specific to
<br />SHS that can provide a valid estimate of the overall magnitude,
<br />duration, and frequency of exposure (USDHHS, 2006). One
<br />such marker is RSP, which can be assessed in real time using
<br />relatively low cost, and standardized, measurement techniques
<br />(Jaakkola and Jaakola, 1997). The primary benefit of using
<br />real-time monitors to assess SHS is that pollution levels can be
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<br />correlated with specific instances of active smoking and then
<br />tracked over time and space to identify mechanisms of exposure.
<br />Additionally, real-time monitors can measure RSP levels over a
<br />period of seconds, thus enabling researchers to determine peak
<br />pollution levels and to make direct comparisons with existing
<br />health standards and outcomes (Klepeis, Ott, and Switzer, 2007).
<br />To our knowledge, no study has assessed the extent to which
<br />SHS distributes throughout MUH in real time. Therefore, the
<br />objective of this study was to simultaneously assess real-time
<br />PM25 levels in smoke -permitted living units, smoke-free living
<br />units, and shared hallways within the same MUH building.
<br />Participants
<br />Participants for this study were recruited between July 2008 and
<br />August 2009 via personal contacts, Internet advertisements, and
<br />flyer postings in the Buffalo, New York, area. Participant selec-
<br />tion included an initial screening process to identify individuals
<br />who currently reside in MUH structures comprised both
<br />smoke -permitted and smoke-free units. A smoke -permitted
<br />unit was defined as a personal living unit in which the resident
<br />reported that smoking occurred on a daily basis, while a smoke-
<br />free unit was defined as a unit in which the resident reported
<br />that smoking was completely prohibited. After individuals from
<br />both types of units were identified within a single MUH struc-
<br />ture, participants were formally invited to participate and the
<br />following eligibility criteria were verified: (a) willingness to
<br />allow research staff to enter and place continuously operating
<br />air monitoring equipment in their unit for at least 72 hr and (b)
<br />willingness and ability to keep a daily activity log describing the
<br />presence and time of activities that could affect air quality levels.
<br />Although an eligible building had to contain at least one smoke -
<br />permitted unit and one smoke-free unit, there was no set limit
<br />as to the quantity of units that could participate within a single
<br />building.
<br />Procedures
<br />Research staff visited each eligible residential unit to measure
<br />room dimensions, obtain informed consent, administer a brief
<br />questionnaire, provide instructions on completing the daily ac-
<br />tivity log, and setup the air monitoring equipment. Air monitors
<br />were simultaneously positioned in smoke -permitted and smoke-
<br />free units within the same building and were operated concur-
<br />rently during the assessment period. Within each unit, air
<br />monitors were placed in a location identified as the primary liv-
<br />ing area, which was most commonly the living room for both
<br />smoke -permitted (94%) and smoke-free (86%) units. When fea-
<br />sible, additional monitors were also simultaneously stationed in
<br />a shared hallway between participating units and on the outdoor
<br />patios of smoke-free units. The patio monitors were included in
<br />the study to provide a control measure to which the indoor loca-
<br />tions could be compared. Criteria for feasibility of a hallway and/
<br />or outdoor monitor included the presence of both an electrical
<br />source and a structure to which the monitor could be securely
<br />locked. To corroborate the validity of PM25 levels, vapor phase
<br />nicotine, a highly specific indicator of tobacco smoke (Jaakkola
<br />and Jaakola, 1997), was assessed in one of the buildings (Build-
<br />ing 11). Hourly outdoor PM2 5 levels were also obtained from a
<br />nearby Department of Environmental Conservation monitoring
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