Tag Archives: air pollution

An example of why best available science is needed when setting air quality regulations

The overall relative risks reported in this study are so low they do not even support the conclusions stated by the authors. Based on these relative risk findings following accepted practice there is no difference in risk and no meaningful opportunity for risk reduction by setting strict air quality limits, contrary to what the authors claim. If I am reading the article correctly, the reported associations are much weaker than weak (essentially, none).

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Ana M Vicedo-Cabrera, et al. Short term association between ozone and mortality: global two stage time series study in 406 locations in 20 countries, BMJ, 2020; 368, https://doi.org/10.1136/bmj.m108

Objective: To assess short term mortality risks and excess mortality associated with exposure to ozone in several cities worldwide.

Design: Two stage time series analysis.

Setting: 406 cities in 20 countries, with overlapping periods between 1985 and 2015, collected from the database of Multi-City Multi-Country Collaborative Research Network.

Population: Deaths for all causes or for external causes only registered in each city within the study period.

Main outcome measures: Daily total mortality (all or non-external causes only).

Results: A total of 45 165 171 deaths were analysed in the 406 cities. On average, a 10 µg/m3 increase in ozone during the current and previous day was associated with an overall relative risk of mortality of 1.0018 (95% confidence interval 1.0012 to 1.0024). Some heterogeneity was found across countries, with estimates ranging from greater than 1.0020 in the United Kingdom, South Africa, Estonia, and Canada to less than 1.0008 in Mexico and Spain. Short term excess mortality in association with exposure to ozone higher than maximum background levels (70 µg/m3) was 0.26% (95% confidence interval 0.24% to 0.28%), corresponding to 8203 annual excess deaths (95% confidence interval 3525 to 12 840) across the 406 cities studied. The excess remained at 0.20% (0.18% to 0.22%) when restricting to days above the WHO guideline (100 µg/m3), corresponding to 6262 annual excess deaths (1413 to 11 065). Above more lenient thresholds for air quality standards in Europe, America, and China, excess mortality was 0.14%, 0.09%, and 0.05%, respectively.

Conclusions: Results suggest that ozone related mortality could be potentially reduced under stricter air quality standards. These findings have relevance for the implementation of efficient clean air interventions and mitigation strategies designed within national and international climate policies.

Small epidemiological associations do not imply a significant risk

“When effects are this small, it is extremely possible that the effects are not real, but are artifacts of the statistical methods used in the original analysis.  If these findings had had Relative Risks or Risk Ratios of 4.0 or 7.9 or any value that might indicate a strong association, then I would be more convinced.  But with so many of the metrics not even passing the most basic test of significance, I am concerned that the findings represent only what John P.A. Ioannidis has termed “simply accurate measures of the prevailing bias.” “  click here

Meta-analyses are very squishy when something is made up out of nothing

S. Stanley Young and Warren B. Kindzierski. Evaluation of a meta-analysis of air quality and heart attacks, a case studyCritical Reviews in Toxicology  https://doi.org/10.1080/10408444.2019.1576587

It is generally acknowledged that claims from observational studies often fail to replicate. An exploratory study was undertaken to assess the reliability of base studies used in meta-analysis of short-term air quality-myocardial infarction risk and to judge the reliability of statistical evidence from meta-analysis that uses data from observational studies. A highly cited meta-analysis paper examining whether short-term air quality exposure triggers myocardial infarction was evaluated as a case study. The paper considered six air quality components – carbon monoxide, nitrogen dioxide, sulphur dioxide, particulate matter 10 lm and 2.5 lm in diameter (PM10 and PM2.5), and ozone. The number of possible questions and statistical models at issue in each of 34 base papers used were estimated and p-value plots for each of the air components were constructed to evaluate the effect heterogeneity of p-values used from the base papers. Analysis search spaces (number of statistical tests possible) in the base papers were large, median 1⁄4 12,288 (interquartile range 1⁄4 2496 ” 58,368), in comparison to actual statistical test results presented. Statistical test results taken from the base papers may not provide unbiased measures of effect for meta-analysis. Shapes of p-value plots for the six air components were consistent with the possibility of analysis manipulation to obtain small p-values in several base papers. Results suggest the appearance of heterogeneous, researcher-generated p-values used in the meta-analysis rather than unbiased evidence of real effects for air quality. We conclude that this meta-analysis does not provide reliable evidence for an association of air quality components with myocardial risk.

Preoccupation with decarbonization is diverting attention in the wrong direction

PM2.5 not likely associated with premature deaths

James E. Enstrom. Scientific Distortions in Fine Particulate Matter Epidemiology. Journal of American Physicians and Surgeons Volume 23 Number 1 Spring 2018

The theoretical prevention of premature deaths from the inhalation of fine particulate matter is being used by the U.S. Environmental Protection Agency (EPA) to justify the National Ambient Air Quality Standard (NAAQS) and multibillion dollar regulations across the U.S., including the EPA Clean Power Plan and the California Air Resources Board (CARB) Truck and Bus Regulation. The epidemiology is severely flawed. Fine particulates probably make no significant contribution to premature mortality in the U.S. The publication of null findings has been blocked or marginalized and studies claiming excess mortality need to be reassessed. click here

USEPA revises New Source Review (NSR) guidance, simplifies permitting

The Environmental Protection Agency issued a guidance to clear up uncertainties in obtaining air quality permits required to build or modify facilities, like power plants and refineries. click here

Junk Science Supported by New England Journal of Medicine

“This letter is not a letter to the editor, hoping for publication, so that the authors might comment on or criticize some article in the NEJM. We write to complain that there is a continuing scandal of scientific integrity at the NEJM—junk science in air pollution epidemiology is being sponsored by what most would consider the iconic medical journal of America.” click here