The purpose of this study is to report particle number (PN) and particle mass (PM) concentration changes in the church during three 60-minute Masses held on a cloudy, sunny and rainy day. At each Mass with a similar number of participants the same number of candles was lit and incense was burned. The highest average PN1 and PM1 concentrations of submicrometer particles which respectively amounted to 23.9 pt/cm³ and 241.1 µg/m³ were obtained for the Mass held on a rainy day. During that Mass the maximum PN1 and PM1 concentrations (amounting to 59.4×103 pt/cm³ and 632 µg/m³) were respectively about 15 and 39 times higher than the church background levels. The greatest number of submicrometer particles (about 18.5×10⁹) was inhaled by an average participant of the Mass held on a sunny day and it was approximately 7 times higher than the number that would have been inhaled at the same time outdoors. The greatest mass of such particles (about 195.4 µg) was inhaled by an average participant of the Mass held on a rainy day and it was approximately 8 times higher than the mass of particles that would have been inhaled outdoors during the same time.