The first COVID-19 case in Turkey was reported by the Ministry of Health of the Republic of Turkey on March 10 2020. From this date, some restrictions were introduced by the Government of the Republic of Turkey in many cities. At first, due to the increasing number of cases, curfews were declared in 31 cities between 11-12 April 2020. Later, curfews continued to be applied every weekend and on public holidays. Both human and industrial activities came to a halt with these restrictions. In general, it was considered more meaningful to determine how much curfews could reduce air pollution, since curfews were not implemented on weekdays. The aim of this study is to determine by how much PM10 and SO2 concentrations decrease with restrictions in Turkey. In this context, data of 61 air quality measurement stations in 31 cities with restrictions were used. The data obtained were compared with the concentration values on the same date in 2019. Mean PM10 concentration levels decreased by 38.69% (ranging from 20.67% to 52.51%) and mean SO2 concentration levels decreased by 33.86% (ranging from 3.66% to 52.41%) compared to 2019. Also, the Pearson correlation coefficient was used to determine the relationship between temperature, wind speed, precipitation and pollutant concentrations in provinces where curfews exist. From this, it was concluded that curfews were more effective than temperature and wind speed to reduce pollutant concentrations. In addition, according to the correlation results obtained between precipitation and pollutant concentrations, it was concluded that wet precipitation is more effective in 2020. The coefficient of divergence (COD) method was used to determine the differences between pollutant sources in 2019 and 2020. According to the results obtained, there were differences in PM10 and SO2 sources between 2019 and 2020 and serious reductions in current air pollution were observed. This study confirmed the effect of restriction of both human and industrial activities on air pollution, and it may be of use for understanding better which activities must be controlled or improved to reduce the impact on the environment.