Heat takes hours and wages from outdoor workers long before it puts anyone in a clinic. The people who work through an Indian summer, on farms, at brick kilns, on construction sites and on public-works schemes where women are most of the workforce, lose hours, wages and safety as the wet-bulb globe temperature climbs. This page takes live weather for any place in India, estimates WBGT hour by hour, applies the occupational screening limits by workload, and reports how many working hours are safe each day this week, what the lost hours cost, and how the count of dangerous-heat days has changed since 1991.
Place
Work
Wages
Enter the local rate: the MGNREGA wage is notified per state each April, and casual agricultural and construction wages differ by district and by sex.
This week
How the hours are judged
WBGT is estimated each hour from air temperature and relative humidity with the Australian Bureau of Meteorology approximation, WBGT = 0.567·T + 0.393·e + 3.94, where e is water-vapour pressure in hPa, e = (RH/100)·6.105·exp(17.27·T/(237.7+T)). The approximation assumes moderately high solar radiation and light wind, so it overstates the hazard in shade and at night; for the shade setting, and for hours with little solar radiation, the page instead uses 0.7·Tw + 0.3·T with the natural wet-bulb from Stull's (2011) formula. The hourly WBGT is then compared with the ACGIH threshold limit values (acclimatised) or action limits (unacclimatised) for the chosen workload: the table gives the highest WBGT at which work can occupy 75–100%, 50–75%, 25–50% and 0–25% of each hour, and the page assigns each hour the largest allocation still permitted (100, 75, 50 or 25% of the hour, or none). Hours lost are the hour fractions not permitted, summed over the workday. Wages lost are lost hours over workday hours, times the daily wage, times the number of workers.
Since 1991
How the trend is built
Daily maximum temperature and daily mean relative humidity from the Open-Meteo historical reanalysis (ERA5-based, roughly 10 km cells, so a city's value is an area average and understates urban heat islands). Each day's peak WBGT is estimated with the same approximation, and for each year March to June the page counts days whose peak WBGT reached the 75–100% limit (continuous work no longer permitted) and the 0–25% limit (almost no work permitted) for the chosen workload and acclimatisation. The line is an ordinary least squares trend through the yearly counts, quoted as days per decade with a 95% confidence interval.