Final answer:
Fine particulate matter (PM2.5) is especially dangerous for health as it can penetrate deeply into the lungs, leading to decreased lung function and diseases such as emphysema and lung cancer. Coarse particles can aggravate asthma but are less dangerous compared to fine particles.
Step-by-step explanation:
The effects of particulate matter (PM) on health are significant and vary depending on the size of the particles involved. One of the key distinctions is between coarse and fine particles. Coarse particles may indeed be associated with conditions like aggravated asthma, but it's the fine particles that are particularly dangerous because they have the ability to infiltrate deep into the lungs. This penetration can decrease lung function, and contribute to serious health issues such as emphysema, lung cancer, and chronic bronchitis. Given the choices provided in your question, the most accurate statement is that 'Fine particles are associated with decreased lung function.' This is because fine particles (PM2.5) are small enough to bypass the body's natural defense mechanisms and enter the deeper regions of the respiratory system, causing both immediate and long-term health effects.