In the context of WHO Air Quality Guidelines, consider: 1. The 24-hour mean of PM2.5 should not exceed 15 ug/m3 and annual mean should not exceed 5 ug/m3. 2. Ozone pollution peaks during inclement weather. 3. PM10 can penetrate the lung barrier and enter the bloodstream. 4. Excessive ozone can trigger asthma. Which are correct?