PM	Particulate Matter
PROSPERO	International Prospective Register of Systematic Reviews
NOS	Newcastle-Ottawa Scale
PRISMA	Preferred Reporting Items for Systematic Reviews and Meta-Analyses
WHO	World Health Organization
COPD	Chronic Obstructive Pulmonary diseases
IHD	Ischaemic Heart Diseases
EPA	Environmental Protection Authority
AOD	Aerosol Optimal depth
UCI	Upper Confidence Interval
LCI	Lower Confidence Interval
USA	United States of America