Susceptibility Factors to Ozone-Related Mortality-A Population-Based Case-Crossover Analysis

Abstract

Background and Objective: Hot and cold temperatures significantly increase the risk of death in many regions of the world. Different measures of temperature, including minimum, maximum and apparent temperature, have been used in previous research. Which temperature measure is the best predictor of mortality is not known. Methods: We used mortality data from 106 cities in the US NMMAPS study (years 1987-2000). We examined the association between temperature and mortality using Poisson regression and fitted a non-linear spline for temperature. We examined five measures of temperature, the effect of including relative humidity, and various degrees of freedom for the temperature spline. The best model was defined as that with the minimum absolute residual. The residuals were calculated using crossvalidation. Results: Maximum temperature was selected as the best temperature measure the most often (40 cities in the Ն65-year age group), and apparent temperature the least often (8 cities in the Ͻ65-year age group). Maximum temperature was the best measure in 10 out of 12 months in both age groups. Geographically, maximum temperature was the best measure in cold regions, and minimum temperature in warm regions. Humidity was important in almost every city in the Ն65 year age group. The seasonal variation in humidity showed a surprising peak in usefulness in winter. Conclusion: Apparent temperature is no better than standard measures of temperature in predicting mortality. Maximum temperature was generally the best measure in cold climates and minimum temperature in warm climates. Humidity is an important predictor of mortality in the elderly and its effect should be estimated separately from temperature.

Air pollution and multiple acute respiratory outcomes

“…Mortality is a prolonged effect of PM (lasting 4-6 days) [19,20], while hospitalisations and emergency visits are immediate (lag 0-1 days and up to 3 days, respectively) [7][8][9], suggesting that subjects' characteristics and patient management may affect the probability of these different events. The stronger increase in out-of-hospital than in-hospital mortality [17,21] and recent studies on the protective effects of drugs against air pollutant effects [22,23] give support to our hypothesis that various respiratory outcomes have to be analysed together as multiple effects of air pollutants.…”

“…No important differences in humidity or atmospheric pressure were observed between the cities. Complete data on pollutants and meteorological conditions have been reported in previous papers [17,21,26].…”

“…Increases in hospitalisations and mortality corresponding to 10 mg?m -3 increases in PM10 or NO 2 were estimated and reported as percentages with 95% confidence intervals. More details about the analysis are reported in previous papers [17,21] and methods used to analyse hospitalisations have been fully described in a paper about the cardiovascular effects of PM10 [26].…”

The relationship between ambient particulate matter and respiratory mortality: a multi-city study in Italy

“…Long-term trend and seasonality were controlled for by including a triple interaction of year, month and day of the week in regression models. The mortality analysis methods used have been fully described in a previous article about the effects of ozone [17].…”

A rapid assessment of the impact of hazard reduction burning around Sydney, May 2016

“…Together, these two multicentre studies also reflect the geographical distribution of new evidence published since 2005. Other recent European multicity studies include studies in England & Wales (Pattenden et al, 2010), France (Lefranc et al, 2009), Italy (Stafoggia et al, 2010) and Spain (Ballester et al, 2006).…”