Study finds few health effects from new technology diesel engines

[wxman]

http://pubs.healtheffects.org/getfile.php?u=708

STUDY FINDS FEW HEALTH EFFECTS FROM NEW TECHNOLOGY DIESEL ENGINES:

(Boston, April 12, 2012) The first results of the most comprehensive study ever undertaken of the health effects of exposure to new technology diesel engines has found no evidence of gene-damaging effects in the animals studied, and only a few mild effects on the lungs, according to a report issued today by the Health Effects Institute (HEI)1. The study – the Advanced Collaborative Engine Study (ACES) – is exposing rats and mice for 16 hours a day to emissions from a heavy duty diesel engine meeting stringent 2007 US EPA standards that reduce emissions of fine particles and other pollutants by over 90% from levels emitted by older engines.

The study found that exposures lasting one, three, and in some cases up to twelve months had effects on only a few of the many health markers tested; exposures will continue for the life time of the rats. The few effects that were reported for the rats were mild hyperplasia (cell proliferation) in the lungs and slightly reduced lung function, and were most consistent with exposure to nitrogen oxides in the engine exhaust, which are being further reduced under 2010 US EPA standards now in effect....

[tdi90hp]

interesting...clean diesel is the future!

[VeeDubTDI]

No animals were harmed during the testing of your TDI?

I wonder if they are testing direct injection gassers.

[wxman]

The full report - all 228 pages of it - is available at http://pubs.healtheffects.org/getfile.php?u=709.

[Ski in NC]

I wonder what percentage of the air the rats breathed was exhaust, and what percent was clean air. I could read the report, but I'm lazy.

[wxman]

Originally Posted by Ski in NC

I wonder what percentage of the air the rats breathed was exhaust, and what percent was clean air. I could read the report, but I'm lazy.

According to the report...

...Exhaust was passed through a stock aftertreatment system before injection into a 35.6 cm internal diameter dilution tunnel. The crankcase ventilation effluent joined the exhaust stream downstream of the aftertreatment system. The exhaust was diluted with filtered air under turbulent conditions at the point of injection. The dilution tunnel supply-air flow was approximately 3000 cubic feet per minute. The primary dilution tunnel was a constant–pressure tunnel, rather than constant volume. When exhaust flow increased, the increased pressure caused the dilution air to be dumped into a bypass leg in the test cell. At a distance of 5.5 m from the injection point (in the exposure room), a portion of the diluted exhaust was drawn through an in-line extraction probe. The exhaust mixture was withdrawn from the primary dilution plenum through individual probes and transit lines for each exposure chamber. Each exposure chamber had its own extraction probe and dilution system. Subsequent to this extraction, the exhaust was diluted with filtered, compressed air provided through a rotary dilution/dilution bypass system. Diluting flows were adjusted as needed to reach the final dilution and concentration targets. The residence time of DE in the dilution tunnel and transit lines was less than 5 seconds. After the exhaust reached the exposure chamber, the residence time was approximately 4 minutes. All dilution and transit lines were constructed of stainless steel, and were of near equal lengths for each of the exposure levels. Exhaust was diluted to achieve pre-selected target exposure concentrations of 4.2, 0.8, and 0.1 ppm NO2. This required dilution ratios of approximately 25:1, 115:1, and 840:1. The dilution rate in the primary dilution tunnel was approximately 5:1....

(page 30 of 228)

For reference, the NAAQS for NO2 (nitrogen dioxide) is 100 ppb (one hour) (100 ppb = 0.1 ppm, i.e., the same level as the "low-level exposure"). The "mid-level exposure" and "high-level exposure" vastly exceed the NO2 NAAQS.

[Ski in NC]

Thanks. Real world dilutions will be vastly higher, unless you live under a bus. Or work in a mine. But encouraging that even at high concentrations, the effects seem minimal.

Rats running around near bus exhausts are relieved to know they will remain healthy!!

[pogo]

Nice study, but not perfect.

The HEI ACES review panel criticised the study for some missing positive controls, some of which were unavoidable due to the level of funding:

The (HEI ACES review) panel noted that the study design did not include a side-by-side comparison with an older pre-
2007 model-year engine. While recognizing that
such a “positive control” could not be included as it
would have substantially increased the complexity
and cost of the study and would have posed enormous
logistical challenges, the panel thought that
such a side-by-side comparison could have enhanced
the study. The panel also identified some
other limitations to McDonald and colleagues’ study
— some biochemical assays lacked positive controls
(to determine that each was sensitive enough
to detect changes).

Funding was provided by:

the US Environmental Protection Agency (EPA) and the worldwide motor vehicle industry.