In the context of WHO Air Quality Guidelines, consider the following statements: 1. The 24-hour mean of PM₂.₅ should not exceed 15 μg/m³ and annual mean of PM₂.₅ should not exceed 5 μg/m³. 2. In a year, the highest levels of ozone pollution occur during the periods of inclement weather. 3. PM₁₀ can penetrate the lung barrier and enter the bloodstream. 4. Excessive ozone in the air can trigger asthma. Which of the statements given above are correct ?
Options
(a)1, 3 and 4
(b)1 and 4 only
(c)2, 3 and 4
(d)1 and 2 only
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