Automobile Emissions
Pollution from automobile emissions has become over the past few decades an
issue of great concern. With a growing number of motor vehicles on our roads
great concern has been attributed to the effects of these emissions to our
health and to the environment. Several of the gases emitted, which when present
in certain concentrations in our atmosphere can be toxic, therefor these
ultimate concentrations must never be achieved. Strict legislation as well as
sophisticated control technology has been implemented in the automotive industry
in order to limit the pollution caused. These aspects of automotive pollution
shall be further discussed in this paper. KEYWORDS: Pollution, Car Pollution,

Automotive emissions, Emission gases, Catalysts 1. INTRODUCTION The relationship
between air pollution and automobile exhaust emissions has been established
largely due to studies done in California. At first the problem was believed to
be a combination of smoke and fog, which was similar to problems faced in London
since the middle ages. In Los Angeles the severity of air pollution has caused
vegetation damage, eye and throat irritation, a decrease in visibility as well
as several other effects. Automobile and truck exhausts contain substances which
can adversely affect human health when exposed to concentrations above ambient
level. Emissions from automobiles usually consist of carbon monoxides, oxides
from sulfur and nitrogen, unburned hydrocarbons, smog, and particulate matter,
which includes smoke. Pollutant concentration and time of exposure are the two
main factors which affect human health. Air emissions from automobiles can also
have an overall effect on the environmental quality in several ways. Emissions
from nitrogen oxides (NOx) can contribute to the acid deposition problem,
combinations of NOx and hydrocarbons can help produce ozone and photochemical
oxidants and lastly pollutants from automobiles and ozone formation can
contribute to the ambient air pollution problem in urban areas. As a result of
increasing concern about the role of the motor vehicle in contributing to these
health and environmental problems as well as the possibility of these problems
to increase due to a growing number of cars worldwide, strict legislation has
caused engine emission control technology to quickly develop. As legislations
become more severe, emission control technology is constantly changed or
modified in order to meet the new requirements and reduce the emissions
produced. This report shall focus on the health effects that automotive
emissions such as gases and particulates may have as well as discuss the control
of these emissions via legislation and technology. The technology discussed is
primarily the present technology implemented to control automotive emissions,
namely catalysts. 2. HEALTH EFFECTS OF AUTOMOTIVE EMISSIONS 2.1 EFFECTS OF

GASEOUS EMISSIONS 2.1.1 Carbon Monoxide Carbon monoxide (CO) is found in high
levels in the exhausts of diesel and petrol powered automobiles. CO is a
colorless and odorless gas and can be toxic at certain levels. The effects of
carbon monoxide is felt when inhaled, it enters the blood stream and binds to
hemoglobin (which the CO has a higher affinity than oxygen by 240 to 1). The
resulting compound formed is carboxlhemoglobin. The blood is then unable to
supply oxygen to the cells. And depending the level of exposure, death may be
the ultimate consequence. The formation of carboxlhemoglobin lowers the
available hemoglobin. Normal individuals will not feel any effects until 5% to

10% of hemoglobin is transformed. As carboxlhemoglobin increases, symptoms such
as headaches, visual disturbances, nausea and vomiting and coma may occur. Death
may occur if levels of carboxlhemoglobin reach the vicinity of 70%. Usually
levels of carbon monoxide are low except in enclosed areas. On average most
carboxlhemoglobin levels are under 5%. Since low level exposure to carbon
monoxide is not well understood, it is believed that it might contribute to
cardiovascular disease. The heaviest exposures to motorist occur in heavy (stop
and go) traffic. When considering the effects of carbon monoxide, it is usually
easily overlooked. Barometric pressure has a direct influence of the amount of
oxygen available in the body (especially if there is a drop). But in general
people who live in high altitudes have higher levels of hemoglobin in their
bodies (hence compensates for lower levels of oxygen). For cities at high
elevations with pollution problems such as Mexico the same CO concentrations at
sea level may have no effect to the population but may have impact with those
with health problems. 2.1.2 Nitrogen Oxides There are several species of
nitrogen oxides. But for our discussion we will consider N2O since the others
have relatively no toxic effects. Nitric oxide is produced in the greatest
quantity during combustion. It has no direct effects on health because it has a
tendency to rapidly disappear into the atmosphere. In