openair package. Files are imported from a remote server
operated by AEA that provides air quality data files as R data objects.importSAQN(site = "gla4", year = 2009, pollutant = "all")site = c("gla4",
"ed") --- to import Glasgow Kerbside and Edinbrugh Centre for example.year = 1990:2000. To import several
specfic years use year = c(1990, 1995, 2000) for example.pollutant = c("nox", "no2").importSAQN function is currently released as a
test version. NOTE - Information is required on the site codes for
easy use.importSAQN function has been written to make it easy
to import data from the Scottish Air Quality Network (SAQN) --- openair functions.
The site codes and pollutant names can be upper or lower case. The
function will issue a warning when data less than six months old is
downloaded, which may not be ratified.
The data are imported by stacking sites on top of one another and will
have field names site, code (the site code) and
pollutant. Sometimes it is useful to have columns of site
data. This can be done using the reshape function --- see
examples below.
All units are expressed in mass terms for gaseous species (ug/m3 for NO,
NO2, NOx (as NO2), SO2; and mg/m3 for CO). PM10
concentrations are provided in gravimetric units of ug/m3 or scaled to
be comparable with these units. Over the years a variety of instruments
have been used to measure particulate matter and the technical issues of
measuring PM10 are complex. In recent years the measurements rely on
FDMS (Filter Dynamics Measurement System), which is able to measure the
volatile component of PM. In cases where the FDMS system is in use there
will be a separate volatile component recorded as 'v10', which is
already included in the absolute PM10 measurement. Prior to the use of
FDMS the measurements used TEOM (Tapered Element
Oscillating. Microbalance) and these concentrations have been multiplied
by 1.3 to provide an estimate of the total mass including the volatile
fraction.
The few BAM (Beta-Attenuation Monitor) instruments that have been
incorporated into the network throughout its history have been scaled by
1.3 if they have a heated inlet (to account for loss of volatile
particles) and 0.83 if they do not have a heated inlet. The few TEOM
instruments in the network after 2008 have been scaled using VCM
(Volatile Correction Model) values to account for the loss of volatile
particles. The object of all these scaling processes is to provide a
reasonable degree of comparison between data sets and with the reference
method and to produce a consistent data record over the operational
period of the network, however there may be some discontinuity in the
time series associated with instrument changes.
No corrections have been made to teh PM2.5 data. The volatile component
of FDMS PM2.5 (where available) is shown in the 'v2.5' column.
While the function is being developed, the following site codes should
help with selection.
importAURN for data elsewhere in the UK and
importKCL for importing comprehensive data in and around
London.## import all pollutants from Glasgow Roadside
glas <- importSAQN(site = "gla4", year = 2000:2009)
## import all pollutants from Lerwick rural site (O3)
ler <- importSAQN(site = "lerw", year = 2005:2010)
## import all pollutants from Glasgow/Dundee Centre for 2009
all <- importSAQN(site = c("gla3", "dun3"), year = 2009)Run the code above in your browser using DataLab