PM 2.5 measurements at UNR

PM2.5 aerosol mass concentration obtained from aerosol light scattering
at 532 nm divided by a mass scattering efficiency factor of 3.8 m2/gram.
Data is from the photoacoustic instruments operated by Pat Arnott from
the 4th floor of Physics, UNR.
Archived data.

Press the PM2.5 Graph button to update if needed.
Time on the x axis is given as Local Standard Time (LST) since 2020.
When it is daylight savings time (spring, summer, and fall), add an hour
to get to local daylight time (LDT).

BC measurements at UNR

Black carbon (BC) mass concentration obtained from aerosol light
absorption at 532 nm divided by a mass absorption efficiency factor
of 8.8 m2/gram. Data is from the photoacoustic instruments operated
by Pat Arnott from the 4th floor of Physics, UNR.
Archived data.

Press the BC Graph button to update if needed.
Time on the x axis is given as Local Standard Time (LST) since 2020.
When it is daylight savings time (spring, summer, and fall), add an hour
to get to local daylight time (LDT).

SSA measurements at UNR

Extinction=scattering + absorption.
SSA=scattering/extinction, bright aerosol when close to 1.
SSA small, for example 0.3, aerosol is dark, like diesel soot.
Data is from the 532 nm photoacoustic instruments
Archived data.

Press the SSA Graph button to update if needed.
Time on the x axis is given as Local Standard Time (LST) since 2020.
When it is daylight savings time (spring, summer, and fall), add an hour
to get to local daylight time (LDT).


The rationale for using these optical measurements to estimate PM2.5 and BC mass concentration is discussed in our paper.
The EPA PM2.5 standard is discussed here.
Salt Lake City has PM2.5 issues and has a good discussion (by the Atmospheric Science program at the University of Utah.)
There currently is no separate standard for BC.

Highlighted Days


PM2.5 mass concentration during the Loyalton CA fire, and many other fires in Northern CA due to lightning strikes. This is a new record for Reno/UNR for regional smoke events.



BC mass concentration during the Loyalton CA fire, and many other fires in Northern CA due to lightning strikes. Note that the amount of black carbon produced by the smoke is much less than the total PM2.5. The health rating for BC is currently unknown so the same rating as for total PM2.5 was used.

Photograph at UNR by Jeremy Benik on 19 August 2020.

Photograph at UNR by Jeremy Benik at the same place on a clean winter day.


Here is the PM2.5 from the King Fire on the day of maximum concentration in Reno. This day had higher PM2.5 concentration than any during the Rim fire of 2013 or during July 2008 when fires from Northern CA were intense. We have published a study of the 2008 fire season as noted here.


BC mass concentration during the King Fire. Note that the amount of black carbon produced by the smoke is much less than the total PM2.5. The health rating for BC is currently unknown so the same rating as for total PM2.5 was used.