Measurements of direct solar radiation in polluted atmosphere over Mexico City are used to infer the growth of aerosol optical depth (AOD) due to volcanic aerosol and large volcanic ash particles emerged there between March 28 and April 4, 1982, as a result of El Chichon eruption (17.5°N, 93.3°W, Mexico). These measurements, as well as those conducted in Vancouver (Canada), showed that the initial episode of AOD growth took place in the period between April and July 1982 in both places, being more pronounced in the former. AOD value has fallen down to its usual background level only by February 1993. Secondary AOD maxima have, however, occurred during April–July 1983 period in Mexico and between October 1982 and September 1983 in Vancouver. From results obtained it is concluded that the initial AOD increase in April–July 1982, observed both in Vancouver and Mexico, was mainly due to shortliving volcanic ash particles residing near the ground surface, whereas the secondary AOD maxima were associated with the formation of stratospheric volcanic aerosol.