Question

which air pollutant most contributes to asthma?
carbon monoxide
particulate matter
emissions
contaminated groundwater

Explanation:

Particulate matter (PM) can irritate the respiratory system. Smaller PM (like PM2.5) can penetrate deeper into the lungs. Exposure to particulate matter is linked to exacerbation of asthma symptoms, such as increased wheezing, coughing, and difficulty breathing. Carbon monoxide mainly affects oxygen transport in the blood. "Emissions" is a very broad term. Contaminated groundwater is a water - related pollutant, not an air pollutant relevant to asthma in this context.

Answer:

particulate matter