Tropospheric ozone affects ecosystems by affecting animal respiratory
systems in much the same manner as it affects human respiratory systems. It also
negatively affects plant life by stressing plants to the point of making them less
vigorous (e.g., producing less chlorophyll) and more susceptible to disease and
pests. This results in a decrease in primary productivity, which negatively
impacts food webs and decreases crop yields.
PEROXYACYL NITRATES (PANS)
PANs are secondary pollutants. Since they break apart quite slowly in the
atmosphere into radicals (a group of atoms that are unstable and highly reactive)
and NO 2 , PANs are able to move far away from their urban and industrial origin.
PANs can cause respiratory problems, impair immune systems, cause eye
irritation, and reduce crop yields by damaging plant tissues (e.g., cells, leaves,
etc.) and inhibiting photosynthesis.
Methods to reduce PANs include:
■ Reducing smokestack emissions through baghouse filters, cyclone
precipitators, scrubbers, and/or electrostatic precipitators
■ Reducing the reliance on fossil fuels, especially oil and coal
■ Reducing the incineration of municipal and industrial wastes
■ Limiting wood-burning fireplaces and stoves in new home construction
SULFUR OXIDES (SOX)
The most common sulfur oxide is sulfur dioxide (SO 2 ). Sulfur dioxide is a
colorless gas with a penetrating, choking odor, and it readily dissolves in water
to form an acidic solution. The main emission source of sulfur dioxide is the
burning of fossil fuels used by power stations, oil refineries, and large industrial
plants. Motor vehicles, tar sand extraction, and ore processing, as well as natural
sources such as active volcanoes, marshes, hot springs, and forest fires, also
release sulfur dioxide.
Sulfur dioxide is toxic to a variety of plants and reduces crop yields. Sulfur
dioxide, emitted in sufficient quantities at low or ground level, can combine with
air moisture to cause gradual damage to some building materials (such as
limestone) by forming an acid solution that gradually dissolves the stonework.
Sulfur dioxide irritates the throat and lungs, and, if there are fine dust
particles in the air, it can damage the respiratory system.
Steps that can be taken to reduce the amount of SO 2 in the atmosphere
include: