LAHORE - Incursions of easterly wave, though weak, has caused unusual increase in the humidity and thus causing early setting of muggy weather, experts told The Nation on Friday. As maximum and minimum temperature is on the higher side at the present stage, high level of humidity is multiplying the agony of people by causing considerable increase in the heat index. Normally, easterly starts affecting Pakistan when temperature drops well below 40 degree Celsius. Though easterly wave is not giving rains in Pakistan, its activity in India is increasing humidity here. When humidity is 40 percent or above, people feel more temperature than the recorded value due to high heat index, said Chief Meteorologist Hazrat Mir. Explaining the term heat index, Hazrat Mir said, people feel different temperatures than the recorded value due to level of humidity. People feel heat of 54 degree Celsius when temperature is 42 C and relative humidity is 40 percent. On June 28, temperature was 41 C but as the humidity was 40 percent, it felt like 51 C. On June 29, temperature was 38 C but it felt like 43 C as humidity was 40 percent. Similarly, On June 30, maximum temperature was 34 C but it felt like 36 C as humidity was 41 percent, said Mir, adding, that a chart was available to calculate heat index for various temperature and humidity level for different days. Referring to the consequences of muggy weather and considerable increase in heat index, he said that heart patients should take extra care in the prevailing weather conditions. High level of humidity increases heat index and make weather muggy. The prevailing weather conditions cause the people to sweat profusely in suffocating weather which is dangerous for heart patients, he said, adding, incidents of heart attack in muggy weather are more than other weather conditions.