The National Academies Press

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Pages 87-104

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From page 87... ... This type of research could provide a way of exploring indoor concentrations of various pollutants as well as the effectiveness of filtration and other control strategies. PM2.5 EXPOSURE CONTROL IN SCHOOLS Schools are a critical environment for a susceptible population -- children -- and 15 percent of schools, with 6.4 million students, are less than 250 meters away from a major roadway, an important source of particulate matter (Figure 8-5) Read the entire page →
From page 88... ... Over the past several years, Gall and the members of his research group have been studying traffic-related air pollution constituents in a middle school in Portland, Oregon, that was renovated in 2018 to serve Portland's historically Black community. The school is adjacent to Interstate 5, and measurements of black carbon, ultrafine particles, and PM2.5 taken on the school's rooftop prior to the renovation showed elevated levels of these three types of particulate matter, with the exact burdens changing with wind speed and direction. Read the entire page →
From page 89... ... Research suggests that, in general, the health effects associated with traffic-related air pollutants such as black carbon (Janssen et al., 2011) and ultrafine particles (Schraufnagel, 2020) Read the entire page →
From page 90... ... . Gall attributed the variability to factors such as the presence of indoor sources of particulate matter, how leaky the environment was, and the location of the intervention in the case of standalone air cleaners. Read the entire page →
From page 91... ... In the Portland middle school, the carbon scrubber component of the air cleaning system appears to suppress levels of secondary organic aerosol precursors and thus formation of secondary organic aerosols. Monitoring showed that there is very little particle formation when the air handling system is on, but higher total particle counts in the indoor air than in outdoor air when the system is off. Read the entire page →
From page 92... ... Singer explained that capture efficiency is calculated using carbon dioxide released from gas burners (or alternatively, a tracer gas) , but a different approach is needed for particulate matter. Read the entire page →
From page 93... ... Nonetheless, the results showed that range hoods effectively removed particles when cooking on the back burner and were less efficient at capturing particles released when cooking on the front burners. "When capture efficiency is high for gases, it is high for particles," he said. Read the entire page →
From page 94... ... The short answer, he replied, is no, there is not a specific number at which you might confidently say, ‘Do not let children outside to play in the park adjacent to the school.' He noted that there are no federal standards for ambient black carbon levels, and, while Oregon does have a benchmark, it Read the entire page →
From page 95... ... But, he added, "it becomes quickly a very political process to say where students can go, when can they go there, what is outdoor recess going to look like at a near-roadway school." Asked how the Portland school fared during Oregon's bad wildfire season in 2020, Gall said that he did not have intensive monitoring then, but there were low-cost particle monitors in the school that indicated that the HVAC system did a good job of keeping PM2.5 levels low inside the school during the wildfire event. In fact, there were discussions with the school district and local county health department about the possibility of using the school as a clean air shelter for those who might seek to reduce their exposure during a wildfire. Read the entire page →
From page 96... ... Turning to the subject of range hoods, Chan asked Singer to comment on the idea of phasing out gas stoves as a solution to the indoor particulate matter issue. Singer replied that getting rid of gas stoves would eliminate one important source of ultrafine particles and nitrogen oxides, though it does not remove the need for good ventilation. Read the entire page →
From page 97... ... Singer added that a test method for low-cost particulate matter monitors is making its way through the ASTM5 process and his hope is that when it is produced it will allow a consistent standard to be applied to these monitors. While this standard will be imperfect -- as all standards are -- it will serve as a general reference and help consumers distinguish between products that work fairly well from those that do not work at all. Read the entire page →
From page 99... ... then explained the role of public health in reducing community exposure to fine particulate matter (PM2.5) Read the entire page →
From page 100... ... "A major take-home here, though, is that we need to identify effective ways to change behavior," he said. Drawing from the literature on interventions, Batterman developed a conceptual diagram for thinking about behavior change to improve health by reducing particulate matter levels using filters (Figure 9-1) Read the entire page →
From page 101... ... Based on theory and experimentation, portable air cleaners can reduce particulate matter exposures substantially, and some studies suggest they Read the entire page →
From page 102... ... Batterman noted that many of the homes were not air conditioned in the summer, and 42 of the 89 families also received an air conditioner to control ventilation. Measurements of particulate matter in the houses with air filters showed that they significantly reduced particle number counts in the submicron and 1- to 5-micron size ranges, with reductions in the children's bedroom of 50 to 80 percent during a one-week assessment at the beginning of the study. Read the entire page →
From page 103... ... Batterman noted that operating a portable air cleaner can add over $200 to a household's annual electric bill. Overall, the findings from this study showed that portable air filters can work when they are used, but effectiveness depends on their use, and in particular, on the user's behavior. Read the entire page →
From page 104... ... © 2013. Modeling Filter Performance As a follow-up to this study, Batterman and his collaborators used indoor air quality models to estimate indoor exposures to ambient PM2.5, determine an "equivalent" exposure concentration that considers time and activity patterns, estimate the health benefits of using filters in schools and homes, and calculate the marginal costs of increasing filter use (Batterman et al., 2021) Read the entire page →

From page 87...

... This type of research could provide a way of exploring indoor concentrations of various pollutants as well as the effectiveness of filtration and other control strategies. PM2.5 EXPOSURE CONTROL IN SCHOOLS Schools are a critical environment for a susceptible population -- children -- and 15 percent of schools, with 6.4 million students, are less than 250 meters away from a major roadway, an important source of particulate matter (Figure 8-5)