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Abstract Recently, nitrate (NO 3 – ) levels in winter pollution in eastern China have been increasing yearly and have become the main component of PM 2.5 . The factors contributing to this rise in surface NO 3 – concentrations remain unclear, complicating the development of targeted pollution control measures. This study utilizes observational data from Shanghai during the winter 2019, alongside box model simulations, to recreate the NO 3 − pollution event and identify the key factors in the growth process. The analysis demonstrated that a rise in winter ozone levels significantly promotes NO 3 – production by facilitating NO x conversion via gas-phase and heterogeneous reactions. These findings could explain the correlation between the synchronous increase of surface ozone and NO 3 − in recent years. Furthermore, simulation of control strategies for NO x and volatile organic compounds (VOCs) identified an approach centered on ozone reduction as notably effective in mitigating winter NO 3 – pollution in the Yangtze River Delta.
Zhang et al. (Thu,) studied this question.