African dust storm events (ADE) travel across theAtlantic Ocean(ADEAO) and reach the Puerto Rican coast (ADEPRC), potentially impacting air quality and human health. To what extent seasonal variations in atmospheric particulate matter (PM) size fractions, composition and sources trigger respiratory-adverse effects to Puerto Ricans is still unclear. In the present study, we investigated the pro-inflammatory and cytotoxic effects of PM samples harvested during ADEAO (PM₁₀), ADEPRC (PM_2.5 and PM₁₀) and Non-ADE (Pre-and Post-ADEAO and Non-ADEPRC), using BEAS-2B cells. Endotoxins (ENX) in PM_2.5 and PM₁₀ extracts and traces of metals (TMET) in PM_2.5 extracts were also examined. IL-6 and IL-8 secretion and cytotoxicity were used as endpoints. ADEAO and ADEPRC extracts were found to be more cytotoxic than Non-ADE and ADEAO were more toxic than ADEPRC extracts. PM₁₀ extracts from ADEAO and Post-ADEAO caused significant secretion of IL-8. IL-6 and IL-8 secretion was higher following treatment with PM₁₀ and PM_2.5 ADEPRC than with Non-ADEPRC extracts. ENX levels were found to be higher in PM₁₀ ADEAO than in the rest of the samples tested. TMET levels were higher in PM_2.5 ADEPRC than in Non-ADEPRC extracts. Deferoxamine significantly reduced cytotoxicity and IL-6 and IL-8 secretion whereas Polymyxin B did not. TMET in PM_2.5 fractions is a major determinant in ADEPRC-induced toxicity and work in conjunction with ENX to cause toxicity to lung cells in vitro. ENX and TMET may be responsible, in part, for triggering PM-respiratory adverse responses in susceptible and predisposed individuals.