With continuing air quality alerts for parts of NSW this week, a US study warns that brief exposure to the tiny particles known as PM2.5 can increase hospital admissions for a wide variety of conditions.

Harvard researchers used hospital data for US Medicare patients from 2000-12, examining the relationship between admissions for more than 200 conditions and air pollution — specifically the levels of particulate matter less than 2.5 micrometres in diameter (PM2.5) — on the previous day.

While, as expected, admissions for respiratory disease and cardiovascular complaints rose after a polluted day, they found admissions for many seemingly unrelated conditions also rose.

Short-term exposure to PM2.5 was associated with an increased risk of admissions for septicaemia, fluid and electrolyte disorders, renal failure, and intestinal obstructions.