The Impact of Weather Events on Local Air Quality
Chelsea Walther and Dr. Sondra Miller
The College of Idaho and College of Engineering, Boise State University
Introduction:
We are examining the atmospheric particulate matter (PM) samples
in areas representing varying populations—urban and rural—by
comparing data from two local sites.
This data is relevant to public health because atmospheric pollution
impacts respiratory health and the contamination of drinking water.
Methods:
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Identify masses of atmospheric PM
Discover local and regional origins of known contaminants
Monitor large weather events, such as forest fires and sandstorms, during and following the events
Urban - Boise State University (BSU)
Rural - Dry Creek Experimental Watershed (DCEW)
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Objectives:
• PM10 are particles 10 µm or smaller in diameter
• Caused by human or natural chemical processes
• Small enough to be inhaled
• PM2.5 are particles 2.5 µm or smaller in diameter
• Caused by human processes such as combustion
• Small enough to accumulate deep in the lungs
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Located north of Boise in the foothills
Approximate elevation 5,500 feet
Uses two passive bucket samplers
Collects both wet and dry deposition in one-week cycles
Samples are rinsed with de-ionized water and poured through a filter in a vacuum
pump to collect any particulates
Located on the roof of the Environmental Research Building (ERB)
Approximate elevation 2,800 feet
Uses two active Micro-Orifice Uniform Deposition Impactors (MOUDI)
Collects PM ranging from 0.056 µm to 18 µm in diameter during 24-hour cycles
Aluminum foil substrates collect different sizes of particulates within the MOUDIs
and are weighed to find the mass of the particulates.
Data Analysis:
Urban Air Samples 2014 vs. 2015
6.0
With summer storms bringing more precipitation than normal, we observed that PM levels have slightly decreased over
the last two months at our urban collection site.
Mass (mg)
Because of the low baseline PM levels, we were able to analyze the impact of two local fires.
Mass (mg)
Urban Air Samples
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
5.0
Two outlier samples affected by
urban fires
Highest PM without forest
fires
4.0
2015
3.0
2014
2.0
1.0
0.0
6/5
Decrease in PM after
rain storms
6/5
6/10
6/15
6/20
6/25
6/30
7/5
Sample Date
7/10
7/15
7/20
7/25
6/10
6/15
6/20
6/25
6/30
7/5
Sample Date
7/20
7/25
Rural Air Samples 2014 vs. 2015
Rural Air Samples
Dry
Wet
7/14
We observed a significant urban change in PM mass during an active fire season
(left), with an average of 2.2 mg per day, in contrast to a non-active season
(right), with an average of 0.8 mg per day. The 1.14 inches of precipitation
received this summer as opposed to the .35 inches received last summer further
served to enhance the difference in air quality
Mass (mg)
20
40
30
20
10
0
6/30
7/8
Sample Week
7/15
In contrast to the extreme difference in urban samples when observing fire events,
our rural site seems to be affected by other factors , which are unrelated to the
wildfire season.
At our rural site, we observed that the PM levels were higher than at our urban
site, however, the abundance of precipitation deposited a higher than normal
amount of PM, which indicates that the rain storms still served to cleanse the air.
6/23
7/10
Last summer, forest fires yielded heavy urban particulate collections, but this summer we have been fortunate to observe
a minimal wildfire season, allowing us to analyze the impact of forest fires on the local pollution levels. The highest levels
of particulate matter this summer are comparable to the lowest levels last summer during forest fire events.
Conclusions:
Mass (mg)
Lowest PM during forest fires
15
2014
10
2015
5
0
6/15
6/23
6/30
Sample Week
7/8
Acknowledgements:
References:
This research was partially funded by the National Science Foundation, Grant #DMR 1359344 via the Research Experience for Undergrads and Teachers in Materials for Energy and Sustainability at Boise State University
NOAA – National Weather
Service Forecast Office