User:Lowy26/The Effect of Lockdown on Air Quality during COVID-19 Pandemic

Lead
Many countries have imposed quarantines and lockdowns to limit the spread of COVID-19, resulting in reduced industrial activity, transport and movement of people. Only essential industries and services are allowed to operate, leading to severe economic repercussions. Contrary to the negative economic and social impact of the pandemic, outdoor air quality has improved in many parts of the world due to reduced emissions of key air pollutants from major sources such as vehicle traffic and industry. This observation suggests that air pollution may be a direct consequence of economic growth and human activity. Unprecedented natural experiments, conducted in a controlled way on a global scale, can be used to improve our understanding of changes in air quality and their causes. This scientific understanding will in turn form the basis for effective environmental policies to improve global air quality by limiting emissions of air pollutants from appropriate anthropogenic sources.

Article body
In response to the rapid spread of COVID-19 and the need to protect public health, some governments around the world took the measure of lockdown in 2020. The lockdown restricted road travel and reduced people's movement. During the reduction in personal travel and economic activity provides, researchers found that the emissions of major air pollutants decreaded a lot. The atmospheric air pollutants include such as particulate matter (PM), nitrogen dioxide (NO2), carbon monoxide (CO), sulphur dioxide (SO2) and volatile organic compounds (VOCs). The similar researches were observed in many countries during lockdowns.

Data
With the COVID-19 spreading out all over the world, the World Air Quality Index project team saw a surge in requests for global data covering the whole world map. As a result, the WAQI project is now providing a new dedicated data-set, updated 3 times a day, and covering about 380 major cities in the world, from January 2015 until now.

The data for each major cities is based on the average (median) of several stations. The data set provides min, max, median and standard deviation for each of the air pollutant species (PM2.5,PM10, Ozone ...) as well as meteorological data (Wind, Temperature, ...). All air pollutant species are converted to the US EPA standard (i.e. no raw concentrations). All dates are UTC based. The count column is the number of samples used for calculating the median and standard deviation.