Suchergebnisse

Ventilated cigarettes were designed to reduce the levels of smoke under machine testing conditions; however, smokers alter their smoking pattern to compensate for the reduction in yields. A relative shift in incidence of lung cancer from the more central lung airways to the alveolar region has also been associated with ventilated cigarette use. Validated mathematical models indicate that particle deposition patterns in the lung depend on particle size and inhalation behavior, including inhalation volume, flow rate, and breath‐hold time. This article finds that most mathematical models underpredict total cigarette smoke particulate (CSP) deposition in the lung, likely because they do not account for coagulation, hygroscopicity, and cloud dynamics, which may increase the effective particle diameter of CSP reaching the lung tissue. The models that include these processes indicate that puff volume would be unlikely to affect particle deposition in the lung, but puff time, inhalation depth, breath‐hold time, and exhalation time may affect total deposition. Most compensation appears to occur through a combination of increased puff volume and puff flow, with possible increases in inhalation depth and breath‐hold time. The complex interaction between the extent of cigarette ventilation, which can affect puffing/inhalation behavior, CSP concentration, and CSP size with CSP dose to the alveolar versus more central lung airways is described. Deposition efficiency in the alveoli could plausibly be increased through compensation, but it is still unclear whether compensation could sufficiently alter patterns of CSP deposition in the lung to elicit a shift in lung cancer sites.

Air pollution is a current and growing concern for Canadians, and there is evidence that ambient levels that meet current exposure standards may be associated with mortality and morbidity in Toronto, Canada. Evaluating exposure is an important step in understanding the relationship between particulate matter (PM) exposure and health outcomes. This report describes the PEARLS model (Particulate Exposure from Ambient to Regional Lung by Subgroup), which predicts exposure distributions for 11 age‐gender population subgroups in Toronto to PM2.5 (PM with a median aerodynamic diameter of 2.5 μm or less) using Monte Carlo simulation techniques. The model uses physiological and activity pattern characteristics of each subgroup to determine region‐specific lung exposure to PM2.5, which is defined as the mass of PM2.5 deposited per unit time to each of five lung regions (two extrathoracic, bronchial, bronchiolar, and alveolar). The modeling results predict that children, toddlers, and infants have the broadest distributions of exposure, and the greatest chance of experiencing extreme exposures in the alveolar region of the lung. Importance analysis indicates that the most influential model variables are air exchange rate into indoor environments, time spent outdoors, and time spent at high activity levels. Additionally, a "critical point" was defined and introduced to the PEARLS to investigate the effects of possible threshold‐pathogenic phenomena on subgroup exposure patterns. The analysis indicates that the subgroups initially predicted to be most highly exposed were likely to have the highest proportion of their population exposed above the critical point. Substantial exposures above the critical point were predicted in all subgroups for ambient concentrations of PM2.5 commonly observed in Toronto after continuous exposure of 24 hours or more.

Abstract
Extreme heat is the leading cause of weather-related mortality in the United States, suggesting the necessity for better understanding population vulnerability to extreme heat. The work presented here is part of a larger study examining vulnerability to extreme heat in current and future climates [System for Integrated Modeling of Metropolitan Extreme Heat Risk (SIMMER)] and was undertaken to assess Houston, Texas, residents' adaptive capacity to extreme heat. A comprehensive, semistructured survey was conducted by telephone at 901 households in Houston in 2011. Frequency and logistic regression analyses were conducted. Results show that 20% of the survey respondents reported heat-related symptoms in the summer of 2011 despite widespread air conditioning availability throughout Houston. Of those reporting heat-related symptoms experienced in the home (n = 56), the majority could not afford to use air conditioning because of the high cost of electricity. This research highlights the efficacy of community-based surveys to better understand adaptive capacity at the household level; this survey contextualizes population vulnerability and identifies more targeted intervention strategies and adaptation actions.

BACKGROUND: Heat wave early warning systems help alert decision-makers and the public to prepare for hot weather and implement preventive actions to protect health. Prior to harmonization, public health units across Ontario either used independent systems with varying methodologies for triggering and issuing public heat warnings or did not use any system. The federal government also issued heat warnings based on different criteria. During heat events, adjacent public health units in Ontario and the federal government would routinely call heat warnings at different times with separate public messages, leading to confusion. This article describes the collaborative process and key steps in developing a harmonized Heat Warning and Information System (HWIS) for Ontario. SETTING: Public health units across Ontario, Canada, collaborated with the federal and provincial government to develop the harmonized HWIS for Ontario. INTERVENTION: In 2011, stakeholders identified the need to develop a harmonized system across Ontario to improve heat warning services, warning criteria, and health messaging. Through a 5-year process facilitated by a non-governmental organization, the three levels of government collaborated to establish the Ontario HWIS. OUTCOMES: The province-wide HWIS was implemented in 2016 with the Ontario Ministry of Health and Long-Term Care's release of the harmonized HWIS Standard Operating Practice, which outlined the notification and warning process. IMPLICATIONS: The lessons learned could help spur action in other provinces and jurisdictions internationally in the development of similar health evidence-based warning systems, including in particular those for protecting public health during extreme heat events. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.17269/s41997-020-00337-y) contains supplementary material, which is available to authorized users.