Six of England's eleven ambulance trust England's ambulance services missed the expected target.
The proportion of Category A calls resulting in an emergency response arriving within 8 minutes during May 2014 was 73.3% nationally, less than the expected standard of 75%.
It was the first time since December 2013 that the Red 1 standard has been missed.
Six of the eleven ambulance trusts (North West, Yorkshire, East Midlands, East of England, London, and South East Coast) did not achieve the 75% standard.
The proportion of Category A (Red 2) calls resulting in an emergency response arriving within 8 minutes was 72.5% nationally, less than the expected standard of 75%.
Only four Trusts achieved the 75% standard. They were the North East, West Midlands, Isle of Wight and South Western.
The national 19 minute response time performance for Category A calls this month of 95.3% and so the national standard of 95% was achieved this month.
Two Trusts failed to achieve the standard for 95% of patients receiving an ambulance within 19 minutes. They were the East of England, and South East Coast.
The total number of emergency calls presented to switchboard this month was 748,195, or 24 thousand per day. The average in 2013/14 was 23,000 per day.
In May 2014, there were 405,078 emergency journeys to a Type 1 or 2 A&E, or aproximately 13,000 per day. The average in 2013/14 was also about 13,000 per day.
Detailed tables of all ambulance Systems Indicators and Clinical Outcomes data are available by clicking here.