Urban photochemical ozone (O3) formation regimes (NOx- and VOC-limited regimes) at nine megacities in East Asia were diagnosed based on near-surface O3 columns from 900 to 700 hPa. nitrogen dioxide (NO2). and formaldehyde (HCHO). which were inferred from measurements by ozone-monitoring instruments (OMI) for 2014–2018. https://mqtimers.shop/product-category/heels/