Efficacy of recent state implementation plans for 8-hour ozone.

The development of state implementation plans (SIPs) for attainment of criteria pollutant standards is an integral component of air quality management in the United States. However, the content and efficacy of SIPs have rarely been examined systematically. Here, 20 SIPs developed in response to the 1997 8-hr ozone standard are reviewed as case studies of attainment efforts at the state level. Comparison of observed and model predicted ozone concentrations shows the US Environmental Protection Agency (EPA) recommended modeled attainment test to be a somewhat conservative predictor of attainment. Among 12 SIPs for regions that sought attainment by 2009, the test correctly predicted attainment and nonattainment in four and five regions, respectively; in the other three regions, attainment was observed despite predictions of nonattainment. However weight-of-evidence determinations and deviations from the recommended modeled attainment test methodology led five of these SIPs to predict attainment that was not in fact observed by 2009; three of those regions achieved attainment in 2010. Ozone and NO2 concentrations declined across much of the United States during the period covered by the SIPs, with rates of improvement strongly correlated with the initial pollution levels and hence greatest in nonattainment regions. However at monitors with mid-range levels of ozone initially, rates of reduction were largely independent of the initial attainment status of the region. This is consistent with thefact that apart from California, the majority of ozone precursor reductions documented by SIPs resulted from federal measures rather than from state or local controls specific to the nonattainment regions.

Unexplained fetal death: are women with a history of fetal loss at higher risk?

AIMS: To identify factors, including the loss of a previous pregnancy before 20 weeks gestation, which are associated with increased risk of singleton antepartum unexplained fetal death (UFD) in Western Australia (WA) using information recorded in routine data collections. METHODS: All fetal deaths in WA from 1990 to 1999 that underwent thorough post-mortem investigations were classified using the Perinatal Society of Australia and New Zealand Perinatal Death Classification System. All UFDs were selected as cases and unmatched controls were randomly drawn from all live births in WA occurring during the study period. Demographic and clinical information on cases and controls was obtained from the WA Midwives' Notification System. Multivariable logistic regression was carried out to determine the independent effect of risk factors and calculate odds ratios. RESULTS: Almost one quarter (22%) of stillbirths were unexplained. Primigravid and primiparous women with a history of pregnancy loss before 20 weeks were at higher risk of UFD than multiparous women who had not experienced any loss. Women with a history of fetal death (after 20 weeks) had the highest risk of UFD. CONCLUSION: The current practice of closely monitoring pregnant women with a history of fetal loss or death should continue as this study suggests they may have a higher risk of poor obstetric outcome. Larger studies are needed to confirm the association between previous pregnancy loss and UFD.

Aetiology of stillbirth: unexplored is not unexplained.

OBJECTIVE: To describe the rate of and demographic factors associated with fetal postmortem investigation and to classify the cause of all fetal deaths that underwent postmortem investigation. To compare the proportion of deaths remaining unexplained after postmortem investigation with estimates derived from death certificates. METHOD: All fetal deaths in Western Australia (WA) from 1990 to 1999 were identified. These data were used to calculate postmortem rates and describe the characteristics of women consenting to postmortems. A multidisciplinary team classified the cause of all deaths that underwent postmortem investigation using the Perinatal Society of Australia and New Zealand Perinatal Death Classification System. The proportion of deaths that were unexplained was compared with estimates based on death certificates. RESULTS: Of the 1,619 fetal deaths recorded for 1990 to 1999, 49% (n=789) underwent complete postmortem investigation. Based on investigations, 22% of the 789 fetal deaths were unexplained and a further 18% were identified as having fetal growth restriction. Based on death certificates, 42% were unexplained and 65% were later explained by postmortem investigation. CONCLUSION AND IMPLICATIONS: Postmortem investigation rates are low. They reveal a cause of death for the majority of cases that are unexplained clinically. Epidemiological investigations of unexplained fetal death based on cases not subject to complete postmortem investigation may lead to inaccurate conclusions. A standardised definition for unexplained fetal deaths that distinguishes between cases with detailed investigation and those with limited or no investigation is needed.