The　mass,　chemical　composition　and　toxicological　properties　of　fine　particulates　(PM2.5)　emitted　from　cooking　activities　in　three　Hong　Kong　based　restaurants　and　two　simulated　cooking　experiments　were　characterized.　Extracts　from　the　PM2.5　samples　elicited　significant　biological　activities　[cell　viability,　generation　of　reactive　oxygen　species　(ROS),　DNA　damage　and　inflammation　effect　(THE-alpha)]　in　a　dose-dependent　manner.　The　composition　of　PAHs,　oxygenated　PAHs　(OPAHs)　and　azaarenes　(AZAs)　mixtures　differed　between　samples.　The　concentration　ranges　of　the　Sigma　30PAHs,　Sigma　17OPAHs　and　Sigma　4AZAs　and　Sigma　7Carbonyls　in　the　samples　were　9627-23,452　pg　m(-3),　503　3700　pg　m(-3),　33-263　pg　m(-3)　and　158　-　5328　ng　m(-3),　respectively.　Cell　viability　caused　by　extracts　from　the　samples　was　positively　correlated　to　the　concentration　of　benzo　[a]anthracene,　indeno　[1,2,3-cd]pyrene　and　1,4-naphthoquinone　in　the　PM2.5　extracts.　Cellular　ROS　production　(upon　exposure　to　extracts)　was　positively　correlated　with　the　concentrations　of　PM2.5,　decaldehyde,　acridine,　E17OPAHs　and　7　individual　OPAHs.　THE-alpha　showed　significant　positive　correlations　with　the　concentrations　of　most　chemical　species　(elemental　carbon,　16　individual　PAHs　including　benzo[a]pyrene,　Sigma　30PAHs,　SO42-,　Ca-2(+),　Ca,　Na,　K,　Ti,　Cr,　Mn,　Fe,　Cu　and　Zn).　The　concentrations　of　Al,　Ti,　Mn,　Sigma　30PAHs　and　8　individual　PAHs　including　benzo　[a]　pyrene　in　the　samples　were　positively　correlated　with　DNA　damage　caused　by　extracts　from　the　samples.　This　study　demonstrates　that　inhalation　of　PM2.5　emitted　from　cooking　could　result　in　adverse　human　health　effects.