No abstract

This study measured and analyzed the outdoor airborne endotoxin concentration, on particulate matter (PM²·⁵ and PM¹⁰), for two cities in the interior of British Columbia, Canada. Samples were collected throughout one seasonal cycle, from October 2005 to September 2006. It was found that concentrations were generally highest in the summer and fall, and lowest in the winter and spring. Temperature and relative humidity were found to be most influential, with highest endotoxin concentrations recorded during warm periods and moderate relative humidity (35 to 75 percent). No clear association of concentration with wind direction was observed. Results were comparable between the two cities considered in this study, and concentrations were similar to or slightly higher than those reported by other studies considering urban locations. Endotoxin concentration was also found to be positively associated with agricultural dust sources identified by a source apportionment study conducted at one of the sampling locations.

Exposure to airborne fine particulate matter has been a pressing issue since the early 1990s when several studies reported health effects at unexpectedly low ambient levels. Since this time, several reviews have addressed various aspects of this topic. This article is the first of a two‐part review of reviews. The intention of these articles is to provide a consolidated overview about fine particulate matter exposure assessment. This article, Part I, begins with a general introduction to particulate matter which includes general properties of particulate matter, how it is classified and how it is associated with health effects. Fundamental concepts related to exposure are also summarized. The remainder of the article focuses on measurement‐based methods for assessing exposure to fine particulate matter. A subsequent article, Part II, addresses modeling approaches used for particulate matter exposure assessment. Current and recommended future directions for assessing exposure to fine particulate matter are also summarized in each of these two articles.

Exposure modeling has become a fundamental component of exposure analysis as it provides an efficient and economical means for assessing exposure of individuals to populations over a variety of spatial and temporal scales for past, current, future, or hypothetical conditions. For airborne particulate matter, traditional modeling approaches typically utilize ambient concentration data to assign exposure levels across an area of interest for a given period of time. Technological advancements have allowed for more sophisticated and innovative modeling approaches that combine exposure measurements and ⁄ or models to integrate the strengths of individual methods. The purpose of this article is to provide a general overview of both conventional and novel approaches of modeling exposure to fine particulate matter.

Operation of an unvented combustion appliance indoors can elevate pollutant levels. We have determined the emission rates and source strengths of a variety of pollutants emitted from eightunvented gasfired space heaters operated with well adjusted air shutters at partial and full input in a 27-m 3 chamber under a range of ventilation conditions. Emission rates were also determined for some heaters with poorly adjusted air shutters. In addition to monitoring carbon monoxide, carbon dioxide,nitric oxide, nitrogen dioxide, formaldehyde, and respirable suspended particles, we also determined oxygen consumption rates.Results indicate that the emissions of nitrogen dioxide and carbon dioxide from all heaters were high enough to be of concern, both in singleroom environments and, based upon calculation, in residential-sized buildings. Depending upon the particular heater and its specific air shutter adjustment, carbon monoxide and, to a lesser extent, formaldehyde emissions can be high enough to cause concern.The emission rates from this study can be used along with information about building characteristics to calculate pollutant levels in a wide variety of indoor environments.