5.14 What are "gross polluters"?
Description
This article is from the Gasoline FAQ, by Bruce Hamilton with numerous contributions by others.
5.14 What are "gross polluters"?
It has always been known that the EPA emissions tests do not reflect real
world conditions. There have been several attempts to identify vehicles on
the road that do not comply with emissions standards. Recent remote sensing
surveys have demonstrated that the highest 10% of CO emitters produce over
50% of the pollution, and the same ratio applies for the HC emitters
- which may not be the same vehicles [91-102]. 20% of the CO emitters are
responsible for 80% of the CO emissions, consequently modifying gasoline
composition is only one aspect of pollution reduction. The new additives can
help maintain engine condition, but they can not compensate for out-of-tune,
worn, or tampered-with engines. There has recently been some unpublished
studies that demonstrate that the current generation of remote sensing
systems can not provide sufficient discrimination of gross polluters without
also producing false positives for some acception vehicles - more work
is required, and in some states I&M emissions testing using dynamometers
is being introduced to identify gross polluters.
The most famous of the remote sensing systems is the FEAT ( Fuel Efficiency
Automobile Test ) team from the University of Denver [99]. This team is
probably the world leader in remote sensing of auto emissions to identify
grossly polluting vehicles. The system measures CO/CO2 ratio, and the
HC/CO2 ratio in the exhaust of vehicles passing through an infra-red light
beam crossing the road 25cm above the surface. The system also includes a
video system that records the licence plate, date, time, calculated exhaust
CO, CO2, and HC. The system is effective for traffic lanes up to 18 metres
wide, however rain, snow, and water spray can cause scattering of the beam.
Reference signals monitor such effects and, if possible, compensate. The
system has been comprehensively validated, including using vehicles with
on-board emissions monitoring instruments.
They can monitor up to 1000 vehicles an hour and, as an example,they were
invited to Provo, Utah to monitor vehicles, and gross polluters would be
offered free repairs [100]. They monitored over 10,000 vehicles and mailed
114 letters to owners of vehicles newer than 1965 that had demonstrated high
CO levels. They received 52 responses and repairs started in Dec. 1991, and
continued to Mar 1992.
The entire monitored fleet at Provo (Utah) during Winter 1991:1992
Model year Grams CO/gallon Number of
(Median value) (mean value) Vehicles
92 40 80 247
91 55 1222
90 75 1467
89 80 1512
88 85 1651
87 90 1439
86 100 300 1563
85 120 1575
84 125 1206
83 145 719
82 170 639
81 230 612
80 220 500 551
79 350 667
78 420 584
77 430 430
76 770 317
75 760 950 163
Pre 75 920 1060 878
As observed elsewhere, over half the CO was emitted by about 10% of the
vehicles. If the 47 worst polluting vehicles were removed, that achieves
more than removing the 2,500 lowest emitting vehicles from the total tested
fleet.
Surveys of vehicle populations have demonstrated that emissions systems had
been tampered with on over 40% of the gross polluters, and an additional 20%
had defective emission control equipment [101]. No matter what changes are
made to gasoline, if owners "tune" their engines for power, then the majority
of such "tuned" vehicle will become gross polluters. Professional repairs to
gross polluters usually improves fuel consumption, resulting in a low cost to
owners ( $32/pa/Ton CO year ). The removal of CO in the Provo example above
was costed at $200/Ton CO, compared to Inspection and Maintenance programs
($780/Ton CO ), and oxygenates ( $1034-$1264/Ton CO in Colorado 1991-2 ), and
UNOCALs vehicle scrapping programme ( $1025/Ton of all pollutants ).
Thus, identifying and repairing or removing gross polluters can be far more
cost-effective than playing around with reformulated gasolines and
oxygenates. A recent study has confirmed that gross polluters are not always
older vehicles, and that vehicles have been scrapped that passed the 1993 new
vehicle emission standards [102]. The study also confirmed that if estimated
costs and benefits of various emission reduction strategies were applied to
the tested fleet, the identification and repair techniques are the most
cost-effective means of reducing HC and CO. It should be noted that some
strategies ( such as the use of oxygenates to replace aromatics and alkyl
lead compounds ) have other environmental benefits.
Action Vehicles Estimated % reduction % reduction
Affected Cost per $billion
(millions) ($billion) HC CO HC CO
Reformulated Fuels 20 1.5 17 11 11 7.3
Scrap pre-1980 vehicles 3.2 2.2 33 42 15 19
Scrap pre-1988 vehicles 14.6 17 44 67 2.6 3.9
Repair worst 20% of vehicles 4 0.88 50 61 57 69
Repair worst 40% of vehicles 8 1.76 68 83 39 47
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