This study of short-term effects of air pollution builds upon previous research conducted in Sofia, expanding its scope to include Plovdiv and Varna, thus offering a broader perspective on the impact of air pollution on respiratory and cardiometabolic diseases in Bulgaria. The exposure-response relationships between hospital admissions for selected diseases (respiratory diseases (RD), ischemic heart disease (IHD), cerebral infarction (CI), and diabetes mellitus (DM)) and daily average air pollution concentrations from 2009 to 2018 were analyzed. Pollutants examined were particulate matter (PM2.5 and PM10), nitrogen dioxide (NO2), sulphur dioxide (SO2), ozone (O3), and carbon monoxide (CO). Employing negative binomial regressions, we examined the effects of air pollution on hospital admissions, considering a seven-day period prior to each admission, while accounting for autocorrelations, time trends, day of the week, temperature, and relative humidity. Finally, we pooled some of the risk estimates across all cities using meta-analysis. Our findings reinforce the initial observations from Sofia, demonstrating a general increase in hospital admissions for RD, IHD and CI associated with higher pollution levels. For DM, the relationship remains less definitive though significant risks were also observed in some cases. Notably, the effect of air pollution on health outcomes displayed regional variations. While our results warrant cautious interpretation, they underscore the potential of air pollution to trigger acute episodes of related respiratory and cardiovascular diseases. This study offers insights for public health strategies and paves the way for further investigations into the environmental determinants of health across Bulgaria.