Indoor Air Mixtures Research Articles

A modeling study of the impact of photolysis on indoor air quality

The importance of photolysis as an initiator of air chemistry outdoors is widely recognized, but its role in chemical processing indoors is often ignored. This paper uses recent experimental data to modify a detailed chemical model, using it to investigate the impacts of glass type, artificial indoor lighting, cloudiness, time of year and latitude on indoor photolysis rates and hence indoor air chemistry. Switching from an LED to an uncovered fluorescent tube light increased predicted indoor hydroxyl radical concentrations by ~13%. However, moving from glass that transmitted outdoor light at wavelengths above 380 nm to one that transmitted sunlight above 315 nm led to an increase in predicted hydroxyl radicals of more than 400%. For our studied species, including ozone, nitrogen oxides, nitrous acid, formaldehyde, and hydroxyl radicals, the latter were most sensitive to changes in indoor photolysis rates. Concentrations of nitrogen dioxide and formaldehyde were largely invariant, with exchange with outdoors and internal deposition controlling their indoor concentrations. Modern lights such as LEDs, together with low transmission glasses, will likely reduce the effects of photolysis indoors and the production of potentially harmful species. Research is needed on the health effects of different indoor air mixtures to confirm this conclusion.

Indoor and Outdoor PM10-Bound PAHs in an Urban Environment. Similarity of Mixtures and Source Attribution.

Given that the European Union lays down air quality objectives associated with outdoor environments, indoor air mixtures' study acquires a remarkable relevance. This work aims to submit a stepwise methodological framework for assessing similarities between indoor and outdoor air mixtures and apportioning potential emission sources. For reaching this goal, PM10 particles were systematically and simultaneously collected at an indoor (dominant emission sources free) and outdoor environment during a year to determine the PAH content in both air mixtures. Broadly, outdoor PAHs levels were higher than at the indoor location, supporting a strong association between both mixtures (r = 0.968, p > 0.001), mainly during the cold period (r = 0.896, p > 0.001). The light molecular weight PAHs were highlighted at the indoor site, in particular to naphthalene and anthracene. Outdoor emission sources influenced the indoor PAH levels, especially high and medium molecular weight PAHs. The local-traffic load was identified as a dominant pollution source responsible for more than half PAHs determined at both environments. Therefore, the control of outdoor emission sources would be translated into an improvement of indoor air quality.

Evaluating the risk of mixtures in the indoor air of primary school classrooms.

In school environments, children are constantly exposed to mixtures of airborne substances, derived from a variety of sources, both in the classroom and in the school surroundings. It is important to evaluate the hazardous properties of these mixtures, in order to conduct risk assessments of their impact on children's health. Within this context, through the application of a maximum cumulative ratio approach, this study aimed to explore whether health risks due to indoor air mixtures are driven by a single substance or are due to cumulative exposure to various substances. This methodology requires knowledge of the concentration of substances in the air mixture, together with a health-related weighting factor (i.e. reference concentration or lowest concentration of interest), which is necessary to calculate the hazard index. Maximum cumulative ratio and hazard index values were then used to categorise the mixtures into four groups, based on their hazard potential and therefore appropriate risk management strategies. Air samples were collected from classrooms in 25 primary schools in Brisbane, Australia. Analysis was conducted based on the measured concentration of these substances in about 300 air samples. The results showed that in 92 % of the schools, indoor air mixtures belonged to the 'low concern' group, and therefore, they did not require any further assessment. In the remaining schools, toxicity was mainly governed by a single substance, with a very small number of schools having a multiple substance mix which required a combined risk assessment. The proposed approach enables the identification of such schools and thus aids in the efficient health risk management of pollution emissions and air quality in the school environment.

Airway effects of repeated exposures to ozone-initiated limonene oxidation products as model of indoor air mixtures

Repeated low-level indoor air exposure to volatile organic compounds (VOCs) may influence the reporting of sensory irritation in the eyes and airways. The ozone-initiated reaction products of limonene, an abundant VOC, were used as a model of indoor air mixtures to study upper airway (sensory) irritation, bronchoconstrictive and alveolar level effects after repeated exposures. Mice were exposed 1h/day for 10 consecutive days to: air, limonene (52ppm/289mg/m3); ozone (0.1ppm/0.2mg/m3); a reaction mixture of limonene (52±8ppm) and ozone (0.5, 2.5 and 3.9ppm) resulting in ∼0.05ppm residual ozone. Neither the limonene nor the ozone exposures alone showed consistent effects on the respiratory parameters. In the limonene/ozone groups, the respiratory rate decreased concentration-dependently with an extrapolated no-effect-level of ∼0.3ppm admixed ozone. Both sensory irritation and airflow limitation were conspicuous effects of the mixtures; sensory irritation appeared rapidly and airflow limitation developed slowly during each exposure. The effects of these parameters did not change with increasing number of exposures. No firm conclusion could be drawn about alveolar level effects. Cells in bronchoalveolar lavage were unchanged irrespective of exposure to air, ozone, and limonene with and without ozone. In conclusion, the study indicated that repeated exposures to ozone-initiated limonene mixtures did not cause sensitization of sensory irritation and airflow limitation. Bronchoalveolar lavage after exposures to ozone, and limonene with and without ozone, respectively, did not show airway inflammation.

Approaches for Assessing Health Risks from Complex Mixtures in Indoor Air: A Panel Overview

Critical to a more definitive human health assessment of the potential health risks from exposure to complex mixtures in indoor air is the need for a more definitive clinical measure and etiology of the health effects of complex mixtures. This panel overview highlights six of the eight presentations of the conference panel discussion and features a number of the major topical areas of indoor air concern. W. G. Meggs assessed clinical research priorities with primary focus on the role of volatile organic chemicals in human health, recognizing the areas where definitive data are lacking. By recognizing many types of chemical sensitivity, it may be possible to design studies that can illuminate the mechanisms by which chemical exposure may cause disease. The critically important topic of multiple chemical sensitivity was discussed by N. A. Ashford, who identified four high risk groups and defined the demographics of these groups. P. A. Schulte addressed the issue of biological markers of susceptibility with specific considerations of both methodological and societal aspects that may be operative in the ability to detect innate or inborne differences between individuals and populations. Three case studies were reviewed. H. Anderson discussed the past and present priorities from a public health perspective, focusing on those issues dealing with exposures to environmental tobacco smoke and formaldehyde off-gassing from materials used in mobile home construction. J. J. Osborne described several case studies involving wood smoke exposure to children, with emphasis on the significantly greater occurrence of chronic respiratory symptoms and acute chest illness for children from homes heated with woodburning stoves.(ABSTRACT TRUNCATED AT 250 WORDS)

Approaches for assessing health risks from complex mixtures in indoor air: a panel overview.

Critical to a more definitive human health assessment of the potential health risks from exposure to complex mixtures in indoor air is the need for a more definitive clinical measure and etiology of the health effects of complex mixtures. This panel overview highlights six of the eight presentations of the conference panel discussion and features a number of the major topical areas of indoor air concern. W. G. Meggs assessed clinical research priorities with primary focus on the role of volatile organic chemicals in human health, recognizing the areas where definitive data are lacking. By recognizing many types of chemical sensitivity, it may be possible to design studies that can illuminate the mechanisms by which chemical exposure may cause disease. The critically important topic of multiple chemical sensitivity was discussed by N. A. Ashford, who identified four high risk groups and defined the demographics of these groups. P. A. Schulte addressed the issue of biological markers of susceptibility with specific considerations of both methodological and societal aspects that may be operative in the ability to detect innate or inborne differences between individuals and populations. Three case studies were reviewed. H. Anderson discussed the past and present priorities from a public health perspective, focusing on those issues dealing with exposures to environmental tobacco smoke and formaldehyde off-gassing from materials used in mobile home construction. J. J. Osborne described several case studies involving wood smoke exposure to children, with emphasis on the significantly greater occurrence of chronic respiratory symptoms and acute chest illness for children from homes heated with woodburning stoves.(ABSTRACT TRUNCATED AT 250 WORDS)

Epidemiologic approaches for assessing health risks from complex mixtures in indoor air.

Indoor air may be contaminated by diverse gaseous and particulate pollutants that may adversely affect health. As a basis for controlling adverse health effects of indoor air pollution, the presence of a hazard needs to be confirmed, and the quantitative relationship between exposure and response needs to be described. Toxicological, clinical, and epidemiological studies represent complementary approaches for obtaining the requisite evidence. The assessment of the effects of complex mixtures poses a difficult challenge for epidemiologists. Understanding the effects of exposure may require accurate assessment of concentrations and personal exposures to multiple agents and analytical approaches that can identify independent effects of single agents and the synergistic or antagonistic effects that may occur in mixtures. The array of epidemiological study designs for this task includes descriptive studies, cohort studies, and case-control studies, each having potential advantages and disadvantages for studying complex mixtures. This presentation considers issues related to exposure assessment and study design for addressing the effects of complex mixtures in indoor air.

Epidemiologic Approaches for Assessing Health Risks from Complex Mixtures in Indoor Air

Epidemiologic Approaches for Assessing Health Risks from Complex Mixtures in Indoor Air

Methodology for assessing health risks from complex mixtures in indoor air. April 17-19, 1990, Arlington, Virginia.

Methodology for assessing health risks from complex mixtures in indoor air. April 17-19, 1990, Arlington, Virginia.