Usage tips and precautions
This section contains suggestions for completing certain data related
tasks.
- Determine if or how much data exists for a time-parameter-geography
combination:
- Retrieve data using the annualdata service.
- If no records are returned, we do not have the data.
- If records are returned, use the observation count to determine the
temporal and geographic distribution of the data.
- Monthly averages:
- AQS does not routinely calculate monthly aggregate statistics.
- If you need these, you must calculate them yourself.
- These can be calculated from the sample data or the daily data
without loss of fidelity.
- Determine a single value for a site with collocated monitors:
- Many sites will have collocated monitors - monitors collecting the
same parameter at the same time.
- The API currently provides only monitor level values. (site-level
values will be added in the future.)
- For some criteria pollutants (PM2.5, ozone, lead, and NO2), the
regulations define procedures for defining a single site-level
value.
- For other pollutants, determining a single site-level value is left
to the investigator.
- Please adhere to the following when using the AQS Data Mart
API:
- Limit the size of queries. The AQS Data Mart
contains billions of values and you may request more than you intend. If
you are unsure of the amount of data, start small and work your way up.
Please limit queries to 1,000,000 rows of data each. You can use the
“observation count” field on the annualdata service to determine how
much data exists for a time-parameter-geography combination.
- Limit the frequency of queries. The AQS Data Mart
can process a limited load. Please wait for one request to complete
before submitting another and do not make more than 10 requests per
minute.
- Be advised that RAQSAPI is capable of retrieving results for
multiple pollutants, this can result in the amount of data being
returned being multiplied by the number of pollutants being
requested.
- Be advised that the AQS Data Mart API limits certain data requests
to one year of data at a time with the exception of the Monitor service.
In order to retrieve multiple years of data for these functions the
RAQSAPI library conveniently sends multiple API requests to the Data
Mart API server, one request for each year, this can result in the
amount of data being returned being multiplied by the number of years of
data being requested.
The AQS Data Mart administrators may disable accounts without
notice for failure to adhere to these terms (Though they will contact
the offending user via the email address provided)