Canadian ED visits track CO, NO2, ozone, and PM
In seven Canadian cities, carbon monoxide and NO2 align with cardiac emergency visits, ozone with respiratory visits, and particles with warm-season asthma.
Source
Air pollution and emergency department visits for cardiac and respiratory conditions: a multi-city time-series analysis
Study at a glance
- Design
- Other — Multi-city daily time-series of ED visits vs gaseous and particulate pollutants
- N
- N=400000 · Nearly 400,000 ED visits to 14 hospitals in seven Canadian cities
- Population
- Cardiac and respiratory emergency department visits in seven Canadian cities
- Outcome
- ED visit associations with CO, NO2, O3, SO2, and PM by season and lag
Structured fields used in claim comparison tables when every cited study has a complete layer.
What they did
Authors pooled daily time-series of ED visits from 14 hospitals in seven cities, linking CO, NO2, O3, SO2, PM10, and PM2.5 at lags 0–2 days (and 3-hour averages) to cardiac and respiratory diagnoses after weather adjustment.
What they found
CO and NO2 showed the most consistent cardiac associations (e.g., warm-season CO: +5.2% MI/angina per 0.7 ppm). Ozone tracked asthma and COPD (COPD +6.2% per 18.4 ppb in the warm season). Warm-season PM10 and PM2.5 were strongly linked to asthma visits. Three-hour same-day averages showed no consistent signal.
The limits
What it doesn't show
Edmonton supplied ~70% of visits, children’s hospitals were missing in most cities, and the design cannot assign personal exposure or prove a single causal pollutant among correlated gases.
Key terms
- Emergency department (ED) visit
- A same-day hospital presentation, capturing a broader population than admissions alone.
- NAPS
- Canada’s National Air Pollution Surveillance network supplying hourly pollutant data.
- Lag 0–2 days
- Pollution on the visit day and the two preceding days.
- Warm season
- The part of the year when people spend more time outdoors and some pollutant–visit associations were larger.
- Pooled multi-city estimate
- A combined effect across cities that can be significant even when single-city estimates are noisy.
Flashcards
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Quiz yourself
Cardiac ED visits associated most consistently with:
Common questions
Why study ED visits instead of deaths?
ED visits include many people who are never admitted (as few as 10% of asthma visits), so they reflect a broader population.
Which pollutants tracked the heart?
CO and NO2, especially myocardial infarction/angina and heart failure at lag 0.
Which tracked the lungs?
Ozone with asthma and COPD; PM10/PM2.5 with warm-season asthma.
Did sub-daily 3-hour peaks matter?
Not consistently, unlike daily averages lagged 0–2 days.
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