Data standards: Date and timestamp guidelines
The Air Sensor Workgroup has developed date and timestamp guidelines to be used during data generation, storage and exchange of air sensor data.
The Air Sensor Workgroup (ASW) adopted these guidelines on 17 January 2017.
This document defines the Date and Timestamp Guidelines for use in the field of air quality measurement and monitoring. It has been derived from ISO 8601 standard, IETF RFC 3339 and the W3C profile.
ASW strongly encourages the manufacturers of low cost sensors, researchers working on air quality and any other air quality data generators and users to use these guidelines.
Purpose of guidelines
Numerous individuals and organizations across the globe have spent effort to measure air quality data and determine the impact of air pollution on human health. However, most of them have been isolated efforts. ASW sees tremendous value in sharing data across data owners so that researchers and other interested parties can take advantage of the vast amount of data to create air quality data products that can help communities worldwide.
The Date and Timestamp guidelines apply to data generation and storage by the sensors and their backend database systems, thus facilitating accurate, reliable and efficient exchange of data across various data owners and data users.
Data generation
Use Epoch time (aka Unix time, POSIX time) which is time in seconds since Unix Epoch (1970-01-01T00:00:00Z) as a 64-bit unsigned integer at the point of generating date/time value by the device.
Human readable timestamp
For the human readable format, convert the Epoch time received from the sensor to the local time adjusted for timezone and Daylight Saving Time (if applicable) based on the location of the sensor and store using the ISO 8601 format as shown below. Use the timezone offset so that this data field is self-contained.
Format: YYYY-MM-DDThh:mm:ss.nnn±hh:mm
Example: 2016-08-25T15:23:22.635-07:00