Automatic Networks produce hourly pollutant concentrations, with data being collected from individual sites by dial-up modem. The data go back as far as 1986 at some sites.
Non-automatic Networks measure less frequently - either daily, weekly or monthly - and samples are collected by some physical means (such as diffusion tube or filter). These samples are then subjected to chemical analysis, and final pollutant concentrations calculated from these results.
A range of simple statistics are routinely calculated by the database for the automatic monitoring data each night. These include:
- Daily mean, maximum and minimum values for all pollutants.
- 8-hour running mean values for ozone and carbon monoxide.
- Daily maximum 8-hour running means for ozone.
- Running 24-hour means for PM10 particulate matter.
There are three options for the output of your database download, according to the size of the data request. Small enquiries can be shown on your screen using minimum HTML, moderately sized enquiries can be e-mailed to you as an attachment in comma separated format, or the largest enquiries will be left on an ftp site, also in comma separated format, for you to collect. The data on the ftp site will be wiped within seven days if it is not retrieved.
The comma-separated format should make it easy to load the file into a spreadsheet once saved to your local machine. If the program does not recognise the format automatically, you will need to set the file type to "Text" and the separator as "Comma" for Lotus, or rename the file to [NAME].csv for Excel.