From:  An expert position paper on environment, occupation and climate change effects on allergic respiratory diseases in Italy

 Guidelines on the impact of short-term exposure to major pollutants on asthma-related outcomes*.

PollutantIncrease above the WHO thresholdHealth effect (latency of effect)
CO10 μg/m3> ED access risk (Lag 0–4)
> Risk of hospitalization (Lag 2 and 4)
NO210 μg/m3> ED access risk (Lag 0–4)
> Risk of hospitalization (Lag 1–4)
O310 μg/m3> ED access risk (Lag 1)
> Risk of hospitalization (Lag 1 and 2)
PM2.510 μg/m3> ED access risk (Lag 0–3)
> Risk of hospitalization (Lag 3)
PM1010 μg/m3> ED access risk (Lag 0–4)
> Risk of hospitalization (Lag 1–3)
SO210 μg/m3> ED access risk (Lag 0–3)
> Risk of hospitalization (Lag 1)
TRAP-< Asthma control
> Risk of asthma exacerbations and asthma hospitalizations
> Use of asthma medication or ED access
< Lung function and asthma-related quality of life

*Modified by [21]. Lag: time interval in days between peak exposure to pollutant and health event. CO: carbon monoxide; ED: emergency department; NO2: nitrogen dioxide; O3: ozone; PM10: atmospheric particulate matter with a diameter ≤ 10 μm; PM2.5: atmospheric particulate matter with a diameter ≤ 2.5 μm; SO2: sulphur dioxide; TRAP: traffic-related air pollution; WHO: World Health Organization.