RAQSAPI - Usage tips and precautions
In RAQSAPI: A Simple Interface to the US EPA Air Quality System Data Mart API

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)