DDL Urban PM2.5, monthly

Dataset: pm25-monthly
Package scope: Parent agglomerations plus ADM1 and ADM2 splits, 1998 onward, monthly
Dataset version: v0.3.0

Contents
- ddl-pm25-monthly.parquet: every monthly observation, all boundary levels
- This README

One file covers all three boundary levels. For parent agglomerations only,
filter on boundary_level = 'PARENT'.

Schema
- id: Parent or child city identifier.
- version: Boundary version.
- boundary_level: PARENT, ADM1 or ADM2.
- pm25_year: Year of the observation.
- pm25_month: Month of the observation, 1-12.
- pm25_version: Upstream raster data version this observation came from.
- pm25_mean: Mean surface PM2.5 inside the polygon for the month.
- pm25_cell_count: Number of grid cells contributing to pm25_mean.

Notes
- 4,330,584 rows covering 1998-2024.
- No CSV is shipped. A plain-text copy of this table is roughly ten times
  the size of the parquet and serves nobody. To convert:
      duckdb -c "COPY (SELECT * FROM 'ddl-pm25-monthly.parquet') TO 'ddl-pm25-monthly.csv' (HEADER, DELIMITER ',')"
- This is a monthly passthrough. No annual aggregate is published here.
- pm25_cell_count below 1 marks an urban area smaller than one 0.01-degree
  grid cell. Those means are computed from a partial cell.

License
- Released under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

Disclaimer
By accepting data provided by the Development Data Lab (DDL), you agree to the following conditions of release and acknowledge the following disclaimers: Neither DDL nor the contributors of data to DDL shall be held liable for any improper or incorrect use or application of the data provided, and assume no responsibility for the use or application of the data or information derived from interpretation of the data. In no event shall DDL or its collaborators be liable for any direct, indirect, or incidental damages arising from the use or application of these data. This disclaimer of liability applies to any damages or injury, including but not limited to those caused by any failure of performance, error, omission, defect, delay in operation or transmission, computer virus, alteration, use, application, analysis, or interpretation of data. No warranty, expressed or implied, is made regarding the accuracy, adequacy, completeness, reliability, or usefulness of any data provided. These data are provided on an "as is" basis. All warranties of any kind, express or implied, including but not limited to fitness for a particular use, freedom from computer viruses, and non-infringement of proprietary rights, are disclaimed. Data are added and changed periodically, and data may become out-of-date quickly. It is recommended that the user not let a significant period of time elapse between obtaining and using the data.
