Author: Clinton Mccrowey physical scientist - US EPA

# RAQSAPI - Introduction to RAQSAPI

#### Clinton Mccrowey physical scientist - US EPA

Warning: US EPA’s AQS Data Mart API V2 is currently in beta phase of development, the API interface has not been finalized. This means that certain functionality of the API may change or be removed without notice. As a result, this package is also currently marked as beta and may also change to reflect any changes made to the Data Mart API or in respect to improvements in the design, functionality, quality and documentation of this package. The authors assume no liability for any problems that may occur as a result of using this package, the Data Mart service, any software, service, hardware, or user accounts that may utilize this package.

# Introduction

The `RAQSAPI` package for the R programming environment allows a R programming environment to connect to and retrieve data from the United States Environmental Protection Agency’s (US EPA) Air Quality System (AQS) Data Mart API v2 Air Quality System1 interface directly. This package enables the data user to omit legacy challenges including coercing data from a JSON object to a usable R object, retrieving multiple years of data, formatting API requests, retrieving results, handling credentials, requesting multiple pollutant data and rate limiting data requests. All the basic functionality of the API have been implemented that are available from the AQS API Data Mart server. The library connects to AQS Data Mart API via Secure Hypertext Transfer Protocol (HTTPS) so there is no need to install external ODBC drivers, configure ODBC connections or deal with the security vulnerabilities associated with them. Most API functions have a parameter, return_header, which by default is set to FALSE. If the user decides to set return_header to TRUE, then that function will return a R AQS_DATAMART_APIv2 S3 object which is a two item named list.
The first item, ($Header) in the AQS_DATAMART_APIv2 object is a tibble2 which contains the header information. The Header contains status information regarding the request (success/fail), any applicable error messages returned from the API, if any exist, the URL used in the request, a date and time stamp noting when request was received and other useful information. The second item of the AQS_DATAMART_APIv2 object ($Data) is a tibble which contains the actual data being requested. For functions with the return_header option set to FALSE (default) a simple tibble is returned with just the $Data portion of the request. After each call to the API a five second stall is invoked to help prevent overloading the Data Mart API server and to serve as a simple rate limit. 1

(1)
AQS data mart welcome https://aqs.epa.gov/aqsweb/documents/data_mart_welcome.html.
(2)
Müller, K.; Wickham, H. Tibble: Simple Data Frames; 2021.

1. RAQSAPI’s rate limit does not guarantee that the user will not go over the rate limit and does not guarantee that API calls do not overload the AQS Data Mart system, each user should monitor their requests independently.↩︎