January 05, 2018

Pollution hysteria in a medical journal

Authors of articles in medical journals are just as excitable about tiny differences as are Warmists.  Warmists get excited about temperature differences of as little as a few hundredths of one degree Celsius and effects roughly as weak as that are often presented with great excitement in medical journals too.  We read below, for instance, that an influence affecting around one person in a million is of importance.

There are circumstances when a tiny difference might mean something but that would be where the measurements concerned are exceedingly precise, free from confounding and well-attested.  But that circumstance never prevails in medical or climate studies.

Just look at the dataset below.  They did NOT in fact measure anybody's exposure to pollution of any sort.  What they did was assess the pollution in an AREA and check who died in that area. That different people in the same area might for various reasons have different levels of exposure to pollution, they blissfully ignored. People who commute from the exurbs to a major city would, for instance, have different pollution exposure to people who worked locally.  So their data has some meaning but is nowhere near precise.

And even the pollution level in each area was not precisely measured. In many cases it was estimated.  So we are looking at imprecise estimates taken in an imprecisely described area.  You would have to find very strong effects indeed to take findings as imprecise as that seriously.  But the effects in the study below are in fact vanishingly small. At best, the findings could support a conclusion that "more research is needed".  They tell us nothing that is even remotely certain. That the pollution studied has no affect at all on anything would be the only cautious conclusion.  So what we actually have is an ideological conclusion: ALL pollution is BAD!

The editor of the journal might reasonably have been expected to inject a note of caution into an evaluation of the findings but he is in fact even more enthusiastic about them.  He sees major public policy implications for the findings. Sigh! JAMA could sometimes pass as a book of fairy stories


Association of Short-term Exposure to Air Pollution With Mortality in Older Adults

Qian Di et al.

Abstract

Importance:  The US Environmental Protection Agency is required to reexamine its National Ambient Air Quality Standards (NAAQS) every 5 years, but evidence of mortality risk is lacking at air pollution levels below the current daily NAAQS in unmonitored areas and for sensitive subgroups.

Objective:  To estimate the association between short-term exposures to ambient fine particulate matter (PM2.5) and ozone, and at levels below the current daily NAAQS, and mortality in the continental United States.

Design, Setting, and Participants:  Case-crossover design and conditional logistic regression to estimate the association between short-term exposures to PM2.5 and ozone (mean of daily exposure on the same day of death and 1 day prior) and mortality in 2-pollutant models. The study included the entire Medicare population from January 1, 2000, to December 31, 2012, residing in 39 182 zip codes.

Exposures:  Daily PM2.5 and ozone levels in a 1-km × 1-km grid were estimated using published and validated air pollution prediction models based on land use, chemical transport modeling, and satellite remote sensing data. From these gridded exposures, daily exposures were calculated for every zip code in the United States. Warm-season ozone was defined as ozone levels for the months April to September of each year.

Main Outcomes and Measures:  All-cause mortality in the entire Medicare population from 2000 to 2012.

Results:  During the study period, there were 22 433 862 million case days and 76 143 209 control days. Of all case and control days, 93.6% had PM2.5 levels below 25 ?g/m3, during which 95.2% of deaths occurred (21 353 817 of 22 433 862), and 91.1% of days had ozone levels below 60 parts per billion, during which 93.4% of deaths occurred (20 955 387 of 22 433 862). The baseline daily mortality rates were 137.33 and 129.44 (per 1 million persons at risk per day) for the entire year and for the warm season, respectively. Each short-term increase of 10 ?g/m3 in PM2.5 (adjusted by ozone) and 10 parts per billion (10−9) in warm-season ozone (adjusted by PM2.5) were statistically significantly associated with a relative increase of 1.05% (95% CI, 0.95%-1.15%) and 0.51% (95% CI, 0.41%-0.61%) in daily mortality rate, respectively. Absolute risk differences in daily mortality rate were 1.42 (95% CI, 1.29-1.56) and 0.66 (95% CI, 0.53-0.78) per 1 million persons at risk per day. There was no evidence of a threshold in the exposure-response relationship.

Conclusions and Relevance:  In the US Medicare population from 2000 to 2012, short-term exposures to PM2.5 and warm-season ozone were significantly associated with increased risk of mortality. This risk occurred at levels below current national air quality standards, suggesting that these standards may need to be reevaluated.

JAMA. 2017;318(24):2446-2456. doi:10.1001/jama.2017.17923





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