The winter time air pollution in
Cache Valley, Utah, USA:
Causes and Possible Solutions
Esmaiel Malek
Department of Plants, Soils, Climate
Utah State University
Logan, UT 84322-4820, U.S.A.
Telephone: 435-797-3284, Fax: 435-797-2117, E-mail:
[email protected]
The Utah Department of Environmental Quality has called a ’Red Air Quality Alert’ day
for Davis, Salt Lake, Utah, and Weber Counties for Wednesday February 20, 2008.
The Bear River District Health Department has called a RED day for Cache County.
Wood-burn conditions and health statements are as follows:
Cache County: Air Quality condition as issued by
the Bear River Health Dept.: RED
Health Advisory: Sensitive people (those with
respiratory or heart disease, the elderly, and
children) should reduce prolonged or heavy
exertion outdoors.
http://www.airnow.gov/index.cfm?action=airnow.DisplayTopStory&StoryType=1
Examples of the wintertime air pollution in Cache
Valley, UT
Southwest view of the valley
Wellsville Mountains
Polluted air
Polluted air
February, 2002, 4:00 p.m.
Snow covered hill
January, 2004
Everybody heard the news in January
2004, about the worst national air
pollution in Logan, Cache County, Utah,
U.S.A., a metropolitan area with a
population of 102,720 (Toth et al., 2006).
Among the media’s comments
were:
“Logan’s (the county seat) air is the
dirtiest in the U.S.”
“Logan’s air found worst to breathe in the
U.S.”
Cache Valley on a “good” day (Feb. 25, 2002)
Cache Valley on a “moderate” day (Feb. 23, 2002: PM2.5 ≈ 40 µg/m3)
Cache Valley on a “very bad” day (Feb. 16, 2004; PM2.5 = 101.6 µg/m3)
Pictures: Dr. Martin
What caused the high
concentration of polluted
material in the air in Cache
Valley during the
period of 8 - 15 January, 2004?
Factors responsible for this highly
winter-time polluted air in Cache
Valley can be related to:
♣- Geography,
♠ - Meteorology,
♥ - Environment
-♣ The Cache Valley geographical structure:
North
NW
NE
E
W
Valley
center
SW
SE
The bottom of Cache Valley (about 61 km long by 50 km wide) is about 1372 m
(4500 ft) above msl and it is almost entirely surrounded by steep mountains
reaching over 2743 m (9000 ft) above msl, forming a bowl around the Valley.
♠- Meteorology
A- High pressure:
High atmospheric surface pressure
during the period of 8 - 15 January,
2004, acted as a lid, holding down
the cold polluted air in Cache Valley
under a thick sheet of warm air.
♠- Meteorology (continued)
B- Precipitation & Wind:
January 2004 (hourly data)
b
Wind speed, m/s
Water equivalent, mm/h
12
9
6
3
0
1
3
2
5
4
7
6
9
8
11
10
13
12
15
14
17
16
19
18
21
20
Day
Precip.
U3
23
22
25
24
27
26
29
28
31
30
January 2004 (hourly data)
b
Wind speed, m/s
Water equivalent, mm/h
12
9
6
3
0
1
3
2
5
4
7
6
9
8
11
10
13
12
15
14
17
16
19
18
21
20
23
22
25
24
27
26
29
28
31
30
Day
Precip.
U3
Lack of precipitation and almost
calm conditions during the period of
8 - 15 January, 2004, kept the level of
pollutants high in Cache Valley (no
washout and ventilation).
♠- Meteorology (continued)
C- Snow-covered surface:
(Example of snow in Logan, UT:
Courtesy of Tim Wright)
-January 2004 averaged about 359 mm (14 inches) of snow, which
boosted the cold-surface air temperature which averaged to about
-19.5 oC (-3.1 oF) during this period.
- High reflection of solar radiation by the snow-cover surface during
the day caused less solar radiation absorption and lower
temperatures.
♠- Meteorology (continued)
D- Radiation budget:
Pyrgeometers
Pyranometers
Frost-covered net radiometer
Snow-covered net radiometer
♠- Meteorology (continued)
D- Radiation budget:
Almost cloudless-sky period
Logan, Utah, USA, January 2004
Cloudiness, %
100
75
50
25
31
28
25
22
19
16
13
10
7
4
1
0
DOY
Almost cloudless-sky period
Malek, E. 1997 (c). Evaluation of effective atmospheric emissivity and parameterization of
cloud at local scale. Atmos. Res. 41-54.
Malek, E. (2008). Cloud contribution to the daily and annual radiation budget in a mountainous
valley. Doi.10.1016/j. atmosres.2008.11.029.
♠- Meteorology (continued)
E- Inversion:
Inversion is the increase of temperature with height, which prevents vertical air motion and traps
pollutants in the air.
Vertical air temperature can be measured by radiosonde, tethersonde, acoustic, etc., approaches
(some require complex and expensive equipment).
The Cache Valley vertical air temperatures have been measured by the HOBO temperature
sensor/data logger (Martin, 2006).
Thermister inside the
radiation shield
Data logger
Whiteman et al. 2000
♠- Meteorology (continued)
E- Inversion:
Inversion during the period of 8 - 15 January, 2004.
http://www.arl.noaa.gov.ready-bin/mainarc.pl
The bottom line is that during the winter, Cache Valley typically has a very
small air shed available, where pollutants will accumulate and become
concentrated.
http://www.airquality.utah.gov/Public-Interest/Current-Issues/cache-valley-PM/
Science/CacheValleyScience.htm
- Environment
♣ Air pollution is referred to as the degradation
of air quality resulting from unwanted gases
and particulates occurring in the air.
♣ These substances in the atmosphere may
result in adverse effects to humans, animals,
vegetation, and materials.
♣ The air quality index (AQI) is used for reporting the
severity of air pollution levels to the public.
♣ The AQI incorporates one or a combination of five criteria
pollutants:
1-Ground level ozone,
2- Particulate matter (PM2.5 or PM10, e.g., PM2.5 is the gravitational
mass of all particles with 2.5 µm in diameters),
3- Carbon monoxide,
4- Sulfur dioxide,
5- Nitrogen dioxide.
- An AQI value is calculated daily
for each of these pollutants.
Ground level ozone, and PM2.5 are the major concerns
in Cache Valley.
- The highest AQI for an individual pollutant is the AQI
value for that day.
(http://www.airnow.gov)
Air Quality Index
(AQI) Values
When the AQI
is in this range:
0 to 50
51 to 100
PM2.5 (µg m-3)
0 – 15.4
15.5 – 40.4
101 to 150
40.5 – 65.4
151 to 200
201 to 300
301 to 500
65.5 – 150.4
150.5 – 250.4
> 250.5
Levels of Health Concern
Colors
...air quality conditions are:
...as symbolized
by this color:
Good
Green
Moderate
Yellow
Unhealthy for
Sensitive Groups
Orange
Unhealthy
132 µg
Very Unhealthy
Hazardous
m-3
Red
Purple
Sources of PM2.5 in Cache Valley
The single major contributor of PM2.5 in Cache Valley
is motorized vehicles.
Other minor sources are: home heating and industry.
The atmosphere is ammonia-rich, due in part to
agricultural activities, but ammonia does not produce
particulate matter (PM2.5) until it reacts with nitrogen
oxides (NOx , 8.3x103 kg/d) and sulfur oxides (SOx,
8.5x103 kg/d), from automobile and diesel exhausts to
produce ammonium nitrate and ammonium sulfate.
Martin (2006): http://www.airquality.utah.gov/Public-Interest/Current-Issues/cache-valleyPM/Outreach/Cache%20Valley%20Air%20Quality%20Studies%202006.pdf
Sources of Ammonia in Cache Valley:
- Cache Valley is the State of Utah leader in dairy
products.
Ammonia is produced form (2002 Agriculture Census) :
106,000 cattle, 7,300 sheep and lambs,
7,500 pigs, 1,200+ poultry , and 50,000 minks.
These animals generate a great deal of ammonia
(average 24-h wintertime = 9.2 µg/m3 (13.9 ppb)),
which is a major contributor to the high level of
PM2.5 in the Valley.
On-road automobile emissions
Martin (2006)
- Road-side emissions monitoring of over 12,000 moving vehicles in Cache Valley
showed that approximately 4.5% and 10.3% of the Valley’s vehicles would fail
inspections tests for NOx and VOCs, respectively, and that these vehicles were
responsible for 25.4% and 47.8% of the valley-wide emissions.
- The study also found that majority of the vehicles that would fail would be older
than 1996. as of 2004,
vehicle registrations from the Utah Department of Motor Vehicles showed the
percentage of vehicles that are 1996 or newer be 49.4%, and, therefore, eligible
for vehicle inspection and maintenance (I&M) program.
- Agriculture emissions: Ammonia (NH3)
- Automobile emissions, for instance:
NOx and VOCs (as catalysts)
After being combined:
HNO3 + NH3 → NH4NO3
gas
gas
particle
NH4NO3 = Ammonium Nitrate
which considered as a
particulate matter (PM)
Microscopic view of PM (Courtesy of Dr. Silva, USU).
Chemical Composition of Cache Valley PM2.5
-Ammonium Nitrate = ammonia + nitrogen
oxides (NOx) (mostly from vehicles).
-Ammonium Sulfate = ammonia + sulfur
oxides (SOx) (diesel engines and coal.)
-Organic Carbon = fuel vapors, solvent
vapors and unburned fuel in exhaust from
poorly maintained vehicles.
-Elemental Carbon = incompletely
combusted hydrocarbons (diesel soot,
black and blue exhaust, wood-burning
stoves, black smoke from incomplete coal
burning).
-Crustal Elements = dust from dirt roads and
wind storms off the west desert.
Monitoring sites throughout the Cache Valley
Newly established site
Loading BGI Air Sampler
Comparison of Exposed and
Unexposed Filters
Changing PM 2.5 Filter
Transport of Air Samplers
Downloading RUN Data
BGI PQ200A Air Sampler Control Panel
and Sampling Apparatus
http://atlas.utah.gov/website/amccurrent/
EPA recently strengthened the 24-h PM2.5 standard from the 1997 level of 65 µg m-3,
and retained the current annual fine particle standard at 15 µg m-3 (12-18-2006)..
Take it easy! Life goes on!!
Concluding Remarks
- The wintertime-high levels of particulate matters (PM2.5)
in Cache Valley were associated with significant health
problems within 1-5 days of exposure, ranging from:
asthma attacks, increased ER visits, heart attacks, strokes,
and may be to death.
- Infants, young children, and the elderly were
particularly vulnerable to the effects of PM2.5.
What can be done to alleviate the wintertime high
concentration of air pollutants in the Valley?
- Cache Valley is the State of Utah leader in dairy
products.
Research is necessary to reduce ammonia from
waste products and reduce the nitrogen oxides
(NOx) and sulfur oxides (SOx) from automobile
and diesel exhausts .
Reduction of ammonia from animal waste products
Animal feeding:
- Reduced nitrogen diets (less crude proteins)
- Dietary electrolyte balance to affect pH
Waste treatment (confinement and storage):
- Frequent removal
- Biological nitrification of liquid wastes before
discharge to lagoon
- Acidify manure
- Cover manure pits
Reduction of nitrogen oxides (NOx) and sulfur oxides
(SOx) from automobile and diesel exhausts.
- Identification and repair or removal of old
vehicles could result in a 15 percent reduction of
NOx during wintertime inversions.
- Community education (driving as little as possible,
car pooling, or using public transportation) followed
by behavioral changes with decreased vehicle miles
traveled (VMT) could result in additional
reductions of NOx emissions.
Cache Valley Teens Taking Steps to Help Environment
http://www.ksl.com/?nid=148&sid=818102
Warning tools:
Main Street, Logan
Main Street, Logan
Main Street, Logan
Main Street, Logan
Meteorological and Environmental Aspects of One
of the Worst National Air Pollution Episode
(January, 2004) in Logan, Cache Valley, Utah,
U.S.A.
Esmaiel Malek* and Tess Davis*
Randal S. Martin+
Philip Silva++
* Utah Climate Center, Department of Plants, Soils, and Climate,
Utah State University, Logan, Utah, U.S.A.
+ Department of Civil and Environmental Engineering, Utah State University, Logan, Utah,
U.S.A.
++ Department of Chemistry and Biochemistry, Utah State University, Logan, Utah, U.S.A.
(J. Atmos. Res., 2006)
Questions?