48. Haze weather caused by fine particles is more harmful to human health than sandstorms. Haze weather caused by fine particles is even more harmful to human health than sandstorms. Particles with a particle size of 10 microns or more will Blocked outside the human nose; particles with a particle size between 2.5 microns and 10 microns can enter the upper respiratory tract, but some can be discharged from the body through sputum, etc. , and can also be blocked by the villi inside the nasal cavity, which is harmful to human health Relatively small; and fine particles with a particle size of fewer than 2.5 microns will enter the bronchi after inhaling the body, disturbing the gas exchange in the lungs, causing diseases including asthma, bronchitis and cardiovascular disease. These particles will also enter the blood, Among them, harmful gases, heavy metals, etc. are dissolved in the blood, which is more harmful to human health. What does this text mean? ['Heavy metals will be dissolved in the blood and endanger human health.', 'Fine particles in haze weather are harmful to human health.', 'Different effects of particles with different particle sizes on human health.', 'The pathogenic mechanism of particles of different sizes in severe weather.']