Comparison of hospitalization and mortality associated with short-term exposure to ambient ozone and PM2.5 in Canada.

BACKGROUND: Hospitalization and mortality (H-M) have been linked to air pollution separately. However, previous studies have not adequately compared whether air pollution is a stronger risk factor for hospitalization or mortality. This study aimed to investigate differences in H-M risk from short-term ozone and PM2.5 exposures, and determine whether differences are modified by season, age, and sex. METHODS: Daily ozone, PM2.5, temperature, and all-cause H-M counts (ICD-10, A00-R99) were collected for 22-24 Canadian cities for up to 29 years. Generalized additive Poisson models were employed to estimate associations between each pollutant and health outcome, which were compared across season (warm, cold, or year-round), age (all ages or seniors > 65), and sex. RESULTS: Overall, ozone and PM2.5 showed higher season-specific risk of mortality than hospitalization: warm-season ozone: 0.54% (95% credible interval, 0.20, 0.85) vs. 0.14% (0.02, 0.27) per 10 ppb; and year-round PM2.5: 0.90% (0.33, 1.41) vs. 0.29% (0.03, 0.56) per 10 µg/m3. While age showed little H-M difference, sex appeared to be a modifier of H-M risk. While females had higher mortality risk, males had higher hospitalization risk: for females, ozone 0.87% (0.36, 1.35) vs. -0.03% (-0.18, 0.11) and PM2.5 1.19% (0.40, 1.90) vs. 0.19% (-0.10, 0.47); and for males ozone 0.20% (-0.28, 0.65) vs. 0.35% (0.18, 0.51). CONCLUSION: This study found H-M differences attributable to ozone and PM2.5, suggesting that both are stronger risk factors for mortality than hospitalization. In addition, there were clear H-M differences by sex: specifically, females showed higher mortality risk and males showed higher hospitalization risk.

Air Health Trend Indicator: Association between Short-Term Exposure to Ground Ozone and Circulatory Hospitalizations in Canada for 17 Years, 1996⁻2012.

The Air Health Trend Indicator is designed to estimate the public health risk related to short-term exposure to air pollution and to detect trends in the annual health risks. Daily ozone, circulatory hospitalizations and weather data for 24 cities (about 54% of Canadians) for 17 years (1996⁻2012) were used. This study examined three circulatory causes: ischemic heart disease (IHD, 40% of cases), other heart disease (OHD, 31%) and cerebrovascular disease (CEV, 14%). A Bayesian hierarchical model using a 7-year estimator was employed to find trends in the annual national associations by season, lag of effect, sex and age group (≤65 vs. >65). Warm season 1-day lagged ozone returned higher national risk per 10 ppb: 0.4% (95% credible interval, -0.3⁻1.1%) for IHD, 0.4% (-0.2⁻1.0%) for OHD, and 0.2% (-0.8⁻1.2%) for CEV. Overall mixed trends in annual associations were observed for IHD and CEV, but a decreasing trend for OHD. While little age effect was identified, some sex-specific difference was detected, with males seemingly more vulnerable to ozone for CEV, although this finding needs further investigation. The study findings could reduce a knowledge gap by identifying trends in risk over time as well as sub-populations susceptible to ozone by age and sex.

The distribution of genomic distance between random genomes.

We study the probability distribution of genomic distance d under the hypothesis of random gene order. We translate the random order assumption into a stochastic method for constructing the alternating color cycles in the decomposition of the bicolored breakpoint graph. For two random genomes of length n, we show that the expectation of n - d is O((1/2) log n).

Stability of rearrangement measures in the comparison of genome sequences.

We present data-analytic and statistical tools for studying rates of rearrangement of whole genomes and to assess the stability of these methods with changes in the level of resolution of the genomic data. We construct datasets on the numbers of conserved syntenies and conserved segments shared by pairs of animal genomes at different levels of resolution. We fit these data to an evolutionary tree and find the rates of rearrangement on various evolutionary lineages. We document the lack of clocklike behavior of rearrangement processes, the independence of translocation and inversion rates, and the level of resolution beyond which translocations rates are lost in noise due to other processes.