Photograph courtesy of Herald Examiner Collection, Los Angeles Public Library

Photograph courtesy of Herald Examiner Collection, Los Angeles Public Library

Wednesday, February 11, 2015 was a good day. Santa Ana winds, blowing moderately, had mixed stalled air over the central district of Los Angeles. Levels of ozone and nitrogen oxide were below state and federal maximums, as they had been all month. As it does most days, the amount of "particulate matter" in the air climbed as the traffic increased and industries began their day.

At the end of the previous week, morning fog had pushed levels of unhealthful air higher in coastal Orange and Los Angeles counties. Older adults, children, and anyone with lung or heart disease were advised to avoid prolonged outdoor activities in the hazy air.

By February 11, air quality conditions had moderated, but particulate levels remained elevated throughout much of that day. High levels of fine particles are tied to greater incidence of childhood lung disease and chronic illness in older adults.

Exactly sixty years before, when I was nearly seven and spent the afternoon of February 11, 1955 outside, the weather was as warm as it was on February 11, 2015.The breaths I drew then contained some of the highest levels of air pollution in the nation. The bright sun cooked together particulates from diesel trucks, nitrogen oxide from manufacturing plants, carbon monoxide from car exhaust, sulfur dioxide from oil-fired industrial furnaces, and stray hydrocarbons evaporating from solvents and degreasers, industrial paints, and gasoline. More