Transmission structure painting is a physically demanding job that requires specialized training due to the dangerous and energized nature of the work. Most tower painters retire around age 35 due to the toll on the body. Traditional coating methods for corroded structures involve multiple climbs to complete surface preparation and apply primer, intermediate, and finish coats. Using the most cost-effective method can reduce the number of climbs and thereby reduce labor costs. Standards such as ISO and SSPC provide guidance on selecting coatings and surface preparation methods suited for transmission structures.

1. Transmission Structure Painting
Is unique for the following reasons:
1) A large percentage of the cost is in the number of
climbs=labor.
2) It is often dangerous/energized; so specialized training
is essential.
3) It is physically very demanding; and most tower painters
retire after age 35, with some exceptions!
It combines the art of overcoating (aged coatings) with
painting weathered galvanized, and/or rusted carbon steel
structures.

2. Traditional Coating Methods
For corroded galvanized or rusty carbon steel:
1) Minimal SSPC-SP3, if not SSPC-SP6, as required by
most industrial primers. 1st climb
2) Remove soluble salts and other contaminants. 2nd
3) Rinse off chloride removal solutions to neutralize
the substrate. 3rd climb
4) Primer/Intermediate/Finish coats 4th/5th/6th climbs
Six climbs vs. one or two.
5) 4 climbs vs. two doubles the cost of labor!

3. Most Cost-Effective Method
If you have to climb a tower more than 3 times to
recoat it; you may be using the wrong paint!
1st climb is often complete surface preparation and
priming/sealing in one climb.
2nd climb is often the final climb, applying the 8-10
mils DFT of tower paint (#9200) in one coat, the day
after applying the primer/sealer.
If excess contamination is present on the substrate; it
may be required to treat or remove the contaminants
prior to repainting.

4. History of Tower Paint
Oils used for hundreds of years
1955 Oils pigmented with red, white, and blue lead.
Later replaced with zinc dust, leafing and non-leafing
aluminum, micaceous iron oxide, and barium
metaborate.
Miox was the key replacement for lead; but as a barrier
pigment vs. active rust inhibitor.
Ceramic microspheres added later to improve edge
retention.
Future developments include…..

5. SSPC Technology Update No. 3
Overcoating: Risks, Factors,

6. SSPC Technology Update #1
Surface Tolerant Coatings For Steel
Appropriate for Tower and Pole Coatings
Less Than SSPC-SP6
Contamination: Soluble Salts 10-500 mg/m2.
How to Achieve Similar Protection with less.
Types of Coatings Specified
Barrier and/or Corrosion Inhibitive
Excellent Wetting/Penetration+ Barrier
100-1000 mg/m2 Sulfates

7. Salinity Map
Salinity map showing areas of high salinity (36
o/oo) in green, medium salinity in blue (35 o/oo),
and low salinity (34 o/oo) in purple. Salinity is
rather stable but areas in the North Atlantic,
South Atlantic, South Pacific, Indian Ocean,
Arabian Sea, Red Sea, and Mediterranean Sea
tend to be a little high (green). Areas near
Antarctica, the Arctic Ocean, Southeast Asia, and
the West Coast of North and Central America tend
to be a little low (purple).

11. Knowledge is Power: to create a
successful job.
The more you know about the true corrosion rate of the
environment around your towers or poles; based on accurate
information about the condition of the substrate and the
environment; the better the chances of success.

12. Electric Utility Industry
Transmission Towers, Poles, Substation Structures and
Equipment

13. Old Standards vs New
Pre-1980s: No standards specific to T&D coatings.
A few semi-relevant standards from ASTM and SSPC, but
rarely invoked.
TG 386 - Below-Grade Corrosion Control of Transmission,
Distribution, and Substation Structures by Coating Systems
TG 395 - Atmospheric (Above-Grade) Corrosion Control of
Transmission, Distribution, and Substation Structures by
Coating Systems
STG 41 - Electric Utility Generation, Transmission, and
Distribution

14. Writing T&D coatings specifications using
regional and global standards
NACE/IEEE “Atmospheric (Above-Grade Corrosion
Control of Existing Electric Transmission,
Distribution, and Substation Structures by Coating
Systems” supplemented by ISO and ASTM Standards,
global climate/weather and wind data, to predict corrosion
rates, and to write T&D coatings specifications.
Incorporate environmental data and expanded condition
assessment data into a software program that will select the
appropriate cleaning, surface preparation, and coating
system for any T&D coatings job.

15. Predictive Life Maintenance Program for
Galvanized T&D Structures
Predict Life of New Galvanized Structures: Life prediction
may vary by many decades, depending on multiple variables.
Calculate the corrosion rate.
Schedule future maintenance according to anticipated life of
galvanized structures.
Prioritize maintenance work based on minimizing cost and
maximizing expected life of coatings.
Once optimal windows have been missed, priorities and costs
will change.
Reactive maintenance programs more likely to sacrifice
quality for cost= wait for galvanized to start failing.

16. Measure and Classify Corrosion Influences
More Corrosive Less Corrosive
Wet
Hot
Humid
Polluted Water
Polluted Air
Acids
Chlorides
Dry
Cold
Arid: Low Humidity
Clean Air
Clean Water
Neutral pH
Salt-Free

17. Charts all clearly show huge importance of
environment on life of structure

18. Variable Life of Galvanized 85 years
Documented by ZALAS (Zinc and Lead Asian Service) are
records of studies which conclude that in an (1)Arid Rural
location zinc coating may last more than 100 years. In a (2)
Rural location galvanized coating will last more than 90 years. In
a (3) Mild Coastal environment where the air contains moisture
with a salt (chloride) the zinc coating may last less than 50 years.
In more hostile environment like a (4) Industrial location the life
span of a galvanized coating reduces to more than 40 years
compared to articles in a (5) Marine environment where coating
life may be less than 20 years. Finally in a (6) Severe Marine
location the anticipated life span of a galvanized coating is Less
than 15 years. (Refer to Anticipated life of Zinc Coating Chart
below): Some areas in South America have HDG failures in 5
years.

20. ISO 12944: Environmental
C1:Atmospheres with low level of pollution. Mostly rural
areas.
C2:Urban and industrial atmospheres; moderate sulfur
dioxide pollution.
C3:Coastal areas with low salinity.C4Industrial areas and
coastal areas with moderate salinity.
C4-Industrial areas with high humidity and aggressive
atmospheres. Also coastal and offshore areas with high
salinity.
C5i and C5m- Include coastal marine and industrial
marine; high humidity and aggressive atmospheres.

21. Similar to NACE IEEE Categories
Rural + definition=D= ISO C2, C3
Industrial/Rural + definition=C= ISO C3, C4
Marine + definition=B= ISO C4/C5m
Marine/Chemical + definition=A= ISO C5i and C5m

22. Category Steel Copper Aluminum Zinc
C1 CR <= 10 CR <= 0.9 negligible CR <= 0.7
C2
10 < CR <=
200 0.9 < CR <= 5 CR <= 0.6 0.7 < CR <= 5
C3
200 < CR <=
400 5 < CR <= 12 0.6 < CR <= 2 5 < CR <= 15
C4
400 < CR <=
650 12 < CR <= 25 2 < CR <= 5 15 < CR <= 30
C5 650 < CR 25 < CR 5 < CR 30 < CR
Corrosivity Rates in Grams per square meter per year

25. ISO 12944 consists of the following parts, under the general
title Paints
and varnishes — Corrosion protection of steel structures by
protective
paint systems:
— Part 1: General introduction
— Part 2: Classification of environments
— Part 3: Design considerations
— Part 4: Types of surface and surface preparation
— Part 5: Protective paint systems
— Part 6: Laboratory performance test methods
— Part 7: Execution and supervision of paint work
— Part 8: Development of specifications for new work and
maintenance
Annex A of this part of ISO 12944 is for information only.

26. ISO 12944 + NACE/IEEE Standards
Protective Paint Systems: Part 5: Tool to more accurate
coating solutions. Coating system can meet both
durability expectations and corrosion(environmental)
category.
These tools can fine tune specifications; telling you when
you might want to clean off contamination or not, add
Power Tool cleaning to pitted areas or not, and add DFT
mils to a coating system or not. It may also alert you that a
different primer may be more applicable than another; for
example a rust penetrating epoxy sealer instead of a more
conventional primer; or a higher percentage of spot
sealing/priming, et. al..

27. Location
Type
Average
Temper
ature
RH
Index
UV
Index
Precipit
ation
Index
Acid
Rain
Index
Chloride
Index
AQI
Index
Rankings
1-5 1-5 1-5 1-5 1-5 1-5 1-5
Arizona
4-5 1-2 4-5 1-2 1-2 1-2 2-3
Urban
NE
Coastal
2-3 3-4 1-2 3-4 3-5 4-5 2-3
Houston
Marine +
Industria
l
3-4 4-5 4-5 4-5 2-3 4-5 3-5
Industria
l Non-
1-5 1-4 3 2-5 3-4 1-3 4-5
Environmental Rankings by Location

28. Method and Modifications
Environmental Survey: Generate report with rankings.
Corrosion variables/intensifiers measured and ranked:
Temperature, RH, precipitation/TOW, air quality (SO2, NOx),
acid rain/ pH, ultraviolet exposure, et. al..
Assess condition of structures NACE IEEE R-1 through R-5, or
(ISO 4628): Generate report with rankings+ corrosion rate.
Schedule time of first maintenance at the beginning of the life
cycle of a structure.
Select a category for specified service life of coating system.
Write a coatings specification or long-term maintenance plan,
with most variables taken into consideration.

29. ISO 9223, 9224, and 9225
ISO 9223 “Corrosion of metals and alloys-Corrosivity
of atmospheres-Classification” (Geneva, Switzerland:
ISO, 1992)
ISO 9224 “Corrosion of metals and alloys-Guiding
values for the corrosivity categories of atmospheres”
(Geneva, Switzerland: ISO, 1992)
ISO 9225 “Corrosion of metals and alloys-Corrosivity
of atmosphers-Measurement of pollution (Geneva,
Switzerland: ISO, 1992)

30. ISO 9223:2012 classifies the corrosivity of an
atmosphere based on various measurements.
This standard classifies the corrosivity of an
atmosphere based on measurements of time
of wetness, and pollution categories (sulfur
dioxide, airborne chlorides). The standard
was not intended to be used in extreme service
atmospheres such as those within chemical or
metallurgical processing facilities or where there is
direct contact with salt spray.

31. Sulfur dioxide may be expressed either in terms of a deposition
rate or an airborne concentration. Either measure is to be made in
accordance with ISO 9225. The units used for the sulfur dioxide
categories in the ISO 9223 are as sulfate deposition (SD) rate in
mg m-2 day-1.
SD <= 10 P0
11 < SD <= 35 P1
36 < SD <= 80 P2
81 < SD <= 200 P3

32. Measuring Microenvironments
The corrosivity due to atmospheric conditions can be
greatly affected by local conditions such as wind speed and
direction, dust, debris, humidity, condensation and
electrolytic species. These local conditions can change
greatly within a few meters, depending on patterns in air
turbulence. One extreme example of local variations due to
the corrosivity of a seawater environment is the top deck of
an aircraft carrier, where waves and seawater mist are
abundant.

33. TOW (Time of Wetness)
TOW <= 10= T1
10 < TOW <= 250= T2
250 < TOW <= 2,500= T3
2,500 < TOW <= 5,500= T4
5,500 < TOW= T5
TOW units are hours per year (hours/year) when
relative humidity (RH) > 80% and the temperature > 0oC.

35. Design Changes Corrosion Rates

36. 36
Evaluate Degree of Rusting

39. Acidity in the Atmosphere
Acidity is described in terms of pH (the negative
logarithm of the hydrogen ion concentration in a
solution).
pH scale ranges from 0 to 14 with 7, the midpoint,
being neutral.
Values less than 7 indicate progressively greater
acidity, while above 7 are progressively more
alkaline.
Normal, unpolluted rain generally has a pH of
about 5.6 due to carbonic acid created by CO2 in
the air.

41. Acid Rain pH Map

42. Sources of Acid Precipitation
When atmospheric pollutants such as sulfur dioxide
and nitrogen oxides mix with water vapor in the air,
they are converted to sulfuric and nitric acids. These
acids make the rain acidic, hence the term "acid
rain". Rain returns the sulfur and nitrogen acids to
Earth, and in high concentrations, can cause damage
to natural environments including forests and
freshwater lakes. This form of acid deposition is
known as wet deposition.

43. Nitrogen compounds
Nitrogen compounds
Nitrogen oxides: highly reactive gases formed when
nitrogen in fuel or combustion air is heated to
temperatures above 650deg.C in the presence of
oxygen, or when bacteria in soil or water oxidize
nitrogen-containing compounds.
Nitrogen oxides combine with water to make nitric
acid, which is a major component of atmospheric
acidification.
Excess nitrogen also causes fertilization and
eutrophication of inland waters and coastal seas.

45. Air Pollution Increases Corrosion
salt and water from ocean spray or road salt/water
spray
just water + oxygen from the air (dampness
accelerates corrosion rate)
fertilizers (as a dust) which contain salts other than
NaCl
acids and alkalis (dust or spray)
hydrogen sulfide or sulfur dioxide

47. Table 18.2 -- Urban air toxics of greatest concern
Acetaldehyde Coke oven emissions Manganese compounds
Acrolein Dioxins Mercury compounds
Acrylonitrile 1,2-dibromoethane Methylene chloride
Arsenic compounds 1,3-dichloropropane Nickel compounds
Benzene Propylene dichloride Polychlorinated biphenyls
Beryllium compounds Ethylene dichloride Polycyclic organic matter
1,3-butadiene Ethylene oxide Quinoline
Cadmium compounds Formaldehyde 1,1,2,2-tetrachlorethane
Carbon tetrachloride Hexachlorobenzene Tetrachloroethylene (perchloroethylene)
Chloroform Hydrazine Trichloroethylene
Chromium compounds Lead compounds
Vinyl chloride
Chemicals in the Atmosphere

48. Acid rain caused by SOx and NOx in the air can (and does)
cause corrosion of metals and stone, as well as concrete.
Hydrogen sulfide can cause corroding of metals like iron and
tarnish silver.
Salt spray can corrode iron and steel and erode concrete
Any material which is a powder or fume can deposit on
surfaces and cause water and dew to wet the surface for a
longer peiod of time - wet metals interact with oxygen and
corrode faster.
How Airborne Pollution Increases Corrosion

50. Mapping Global Wind Patterns

55. The presence of hydrosoluble species, mainly chlorides
and sulphates, at the metal/paint interface promotes
osmotic blistering of the coating and underfilm metallic
corrosion when the concentration of the soluble salts
exceeds a critical level. Both processes can lead to the
deterioration of the paint system in a very short period of
time. The International Standards Organization (ISO)
has for some time been trying to develop a standard
about guidance safe levels for water-soluble salt
contamination before the application of paints and
related products. However, it is difficult to set acceptable
unique levels since each type of coating and thickness
varies in susceptibility to soluble salt degradation and
also the exposure conditions vary. In this study, by a
variety of accelerated and natural weathering trials,

56. ISO 4628 Evaluation of degradation of coatings
ISO 4628 is divided into 9 parts, each referring to different defects which can
occur in paint coatings:
ISO 4628-1:2005 Part 1: General introduction and defect designation system
ISO 4628-2:2005 Part 2: Assessment of degree of blistering
ISO 4628-3:2005 Part 3: Assessment of degree of rusting
ISO 4628-4:2005 Part 4: Assessment of degree of cracking
ISO 4628-5:2005 Part 5: Assessment of degree of flaking
ISO 4628-6:2007 Part 6: Assessment of degree of chalking by tape method
ISO 4628-7:2005 Part 7: Assessment of degree of chalking by velvet method
ISO 4628-8:2007 Part 8: Assessment of degree of delamination and corrosion
around a scribe
ISO 4628-10:2005 Part 10: Assessment of degree of filiform corrosion
All parts of the original standard have been transcribed for the Portuguese
Standard, with the exception of
part 6 which is included in ISO 4628-6:2007.
Part 1 of the standard establishes a general system for designating the quantity,
intensity and size of the

57. Life Cycle of HDG
Brand New HDG – Five layers with a surface layer of
100% zinc. Spangled and shiny zinc metal
color.Second Stage HDG – Pure zinc layer reacts with
atmospheric oxygen (O2) and forms a zinc oxide
(OH2) layer. This second stage is also unstable, as is
the first stage, and will normally occur in the first 48
hours.Third Stage HDG – The zinc oxide layer reacts
with moisture in the atmosphere and forms zinc
hydroxide, which is also an unstable form of HDG
requiring special procedures to properly coat. This
third stage of HDG can take from 48 hours to six
months to occur.

58. Eta, Zeta, Delta, Gamma, Steel

59. Stages of Weathered HDG
Fourth Stage HDG – Zinc hydroxide reacts with carbon dioxide in the
atmosphere to form zinc carbamate, which is the first stage of “weathered
galvanized” in that it is a stable form of zinc for coatings purposes. This stage
can take from six months to two years to occur.Fifth Stage HDG (2nd stage of
aged galvanized) – This A1 stage can take a short time to many decades to
occur. It can be described as fully weathered galvanized HDG steel that has not
yet begun to corrode, or has very little zinc/iron alloy layer showing with little
to no staining from exposed layers of zinc/iron alloy exposure.Sixth Stage
HDG (3rd stage of weathering) – <10% of the surface area showing signs of
corrosion and/or zinc/iron alloy staining.Seventh Stage HDG (4th stage of
weathering) – 10-50% of the surface area showing signs of corrosion and/or
zinc/iron alloy staining.Eighth Stage HDG (5th stage of weathering) – 50-
90% of the surface area showing signs of corrosion and/or zinc/iron alloy
staining, and some pitting corrosion as well.Ninth Stage HDG (6th stage of
weathering) – 100% of the surface area corroded, and little to zero galvanized
remaining. Condition is closer to pitted corroded carbon steel, as no galvanized
remains.

60. HDG Phases
1. Initial oxidation 2Zn + O2 = 2ZnO (unstable)
2. Hydration 2Zn + 2H2O + O2 = 2Zn(OH)2
(unstable)
3. Carbonation 5Zn(OH)2 + 2CO2 =
2ZnCO3.3Zn(OH)2 + 2H2O (stable)
4. In salty air 6Zn + 4CO2 = 8NaCl + 7O2 + 6H2O =
4Zn(OCl)2 + 2Zn(HCO3)2 + 8NaOH (unstable)
5. Industrial atmospheres Zn + O2 + SO2 = ZnSO4
(unstable)

61. Categories for Water and Soil
Category Environment : Examples of Environment
and Structures (IM3)
IM 1 Fresh water River installations, hydro-
electric power plants.
IM 2 Sea or brackish water ..Harbor areas with
structures like sluice gates, locks, jetties. Offshore
structures.
IM 3 Soil. Tower footings, Buried tanks, steel piles,
pipes.

62. Galvanic Scale
More Active To more noble
Magnesium
Zinc (hot-dip, die cast, or plated)
Cadmium (plated)
Al 218 (die cast)
Al 5052-H16
Tin (plated)
Stainless steel 430 (active)
Lead
Steel 1010
Iron (cast)
Stainless steel 410 (active)
Copper (plated, cast, or wrought)
Nickel (plated)
Chromium (Plated)
Stainless steel 310 (active)
Stainless steel 301 (active)
Tungsten
Muntz Metal 280
Brass (plated)
Nickel-silver (18% Ni)
Stainless steel 316L (active)
Bronze 220
Copper 110
Stainless steel 347 (active)
Copper-nickel 715
Admiralty brass

63. New Galvanized Steel
Specifications A123/A123M or A153/A153M.
Chromate Quench or not. If not painting in 48 hours, and
given sufficient moisture in air…
Wet storage stain vs. chromate layer removal.
New= Less than 48 hours old.
Partially Weathered= At least 48 hours to less than 2 years
old.
Fully weathered= More than 2 years.
Each phase produces different variables.

64. Dissimilar metals
Stainless steel and aluminium are commonly
used in contact with galvanizing, notably as
fasteners and, except in very corrosive
locations, are most satisfactory. However,
copper and its alloys can accelerate the
corrosion of galvanizing in corrosive
situations, when in direct electrical contact.
Corrosion products of copper and its alloys can
also accelerate the corrosion of galvanizing.

66. Rust
Fe2O3.H2O (hydrous ferrous oxide, sometimes written
as Fe(OH)3) is the principal component of red-brown
rust. It can form a mineral called hematite.
20.5 million tons of nitrogen oxides.
23.1 million tons of sulfur dioxide.

67. Definition of Corrosion
Physicochemical interaction between a metal and
its environment which results in changes in the
properties of the metal and which may often lead
to impairment of the function of the metal, the
environment, or the technical system of which
these form a part. ISO 8044-1986
Corrosion is an irreversible interfacial reaction of
a material (metal, ceramic, polymer) with its
environment which results in consumption of the
material or in dissolution into the material of a
component of the environment. IUPAC

68. Preparing Hot-Dip Galvanized for
Coatings Application
ASTM D6386 - 10 Standard Practice for
Preparation of Zinc (Hot-Dip Galvanized) Coated
Iron and Steel Product and Hardware Surfaces for
Painting
Protective Coating User's Handbook, Second
Edition, Published by NACE
It is a measure of force per unit area, defined as one
newton per square metre.

69. Corrosion rate: 20 Microns Per Year
Severe marine environments such as this ocean front
site may have zinc corrosion rates of around 20
microns or more per year. In this environment, the
galvanized coating on the guardrail has a predicted life
of 3-5 years.

70. ZINC CORROSION MECHANISMS
In the hierarchy of metals, zinc is relatively reactive,
but like aluminium, relies on oxide films that develop
on its surface to provide its superior corrosion
resistance in atmospheric environments. Zinc is also
an amphoteric metal, in that it reacts with both acids
and alkalis.

71. AS/NZS 2699, on the other hand, uses an R0, R1, R2,
R3, R4 and R5 rating criteria that is based on airborne
salt (chloride) deposition.
The draft standard – AS 4312 Corrosivity zones in
Australia, uses a C1,C2, C3, C4 and C5 rating system
that is consistent with the system used in International
(ISO) standards, specifically ISO 9223.

73. Food contact
Food contact
Since IRONOR® is free of toxic ingredients, it is
extremely useful for nonpoisonous finishes
applied to food processing plants such as sugar
refineries, dairy plants, breweries and distilleries.

74. Series 1
Series 2
Series 3
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
Category
1
Category
2
Category
3
Category
4
Series 1
Series 2
Series 3

75. Category Short term Long
term (g m-2 year-1) (mm year-1)
C1 CR <= 10, CR
<= 0.1
C2 10 < CR <= 200, 0.1 < CR
<= 0.5
C3 200 < CR <= 400 1.5 < CR
<= 6
C4 400 < CR <= 650 6 < CR
<= 20
C5 650 < CR 20 < CR

76. TYPICAL COATING WEIGHT (British Standards
729:1971)
Category Min Ave coating weight (g/m2)
Min Ave coating Thickness (Micron) steel
articles > 5mm 610 85 (not centrifuged) <.
5mm 460 64 > 2 mm 335 47 Malleable casting
610 85 Threaded items 305 43 (centrifuged)

77. Visual Assesment of Corrosion
ASTM D610 - 08(2012)
SSPC-VIS 3
Guide and Reference Photographs for Steel
Surfaces Prepared by Hand and Power Tool
Cleaning
SSPC-VIS 2
Standard Method of Evaluating Degree of Rusting
on Painted Steel Surfaces

81. Solvents (Liquids)
Pigments
Additives
Resins (Binder)
Basic Ingredients of A Coating

82. Abstract
The corrosion behaviour of carbon steel at six test sites
in Colombia and its relationship with exposure time and
environmental characteristics of each site were
investigated. The corrosion products were characterized
by XRD, SEM and EDS. It was found that in
Barranquilla, the most aggressive site, corrosion
depends mainly on chlorides. Furthermore, in the more
aggressive environments there was a greater tendency to
formation of protective corrosion products.
Lepidocrocite and goethite were found as major
constituents of rust. A structure not reported in the
literature was found, corresponding to strings of several
hundred micrometers long and consisting of

83. 83
Resins
Types: Latex, Alkyd, Epoxy, Polyurethane
Binds or glues ingredients (pigments and
additives) of paint together
Resin provides adhesion to the substrate
Resin provides durability & resistance properties:
U-V resistance
Moisture resistance
Chemical resistance
Stain resistance
Fade resistance
Chalk resistance
Block resistance

84. Seawater temperature map showing areas of
warmer water in red and areas of cooler water is
blue. White areas represent ice. Notice the upward
finger of cold water in the South Pacific off of
South America and the downward finger of cold
water in the North Pacific off of the West Coast of
the USA. The reasons for these become apparent
when you learn about the major ocean currents
(lesson 2.1.2).
Seawater Temperature Map

86. TOW, UV, Chlorides, Sulfur Dioxide,
Acid Rain,